Viscose Rayon Production in Photos (1948)

Click here to see the Story of Rayon in pictures

Insight, Tampa: 20th - 24th October 2002

Insight once again excelled with its broad coverage of up-to-the-minute marketing and technical issues via mostly original papers presented to a truly international list of over 600 of the great and good of our industry. As noted at other Insight events, the uncrowded program and longer Q&A sessions consistently allow the speakers to present and develop their themes to the full. The result is, perhaps paradoxically, a higher density of what we all attend conferences for: knowledge, information, understanding, and contacts. Key Points Hydroentangling fully calender-bonded spunbond makes it look and feel like a carded-staple product but with more bulk and strength. Lyocell can now be refined to yield low-cost cellulose nanofibers which have been converted into virus filters. A 1tonne/hour production unit will be operating next year. The objective of tampon research should be to reproduce the superb properties of P&G’s Rely™ product, according to a J&J researcher. A ~100% SAP core uses hot melt powder to bond the particles. On wetting this forms into tubes which acquire fluid rapidly and then empty as the SAP absorbs it. Diaper research is bringing diminishing returns. Major brands are perceived as little better than private label. The market declines due to the better products being worn for longer. 1960’s diaper designs made with 2002 machines and materials could yield a 4 cent diaper which would allow the market to grow rapidly in the third world. New contraceptive methods will allow women to choose when to have a period, if ever. 30 years of EDANA statistics Pierre Wiertz of EDANA charted the progress of the European Industry using their uniquely consistent set of industry surveys commencing in 1971. He saw three distinct periods each of a decade: • ‘71-‘81 being characterised by 11.5% overall growth (from 65,000 tonnes in ‘71 to 190,000 tonnes in ‘81). This was driven by the growth of Spunbond and the arrival of one-piece diapers. The collapse of the once dominant apparel interlining nonwoven sector occurred in this period. • '82-'91, with 8.5% growth (205,000 to 450,000 tonnes), highlighting the emergence of air-laid, hydroentanglement and the effect of a 1987 Financial Times Supplement on the industry as attracting new investors. • '92-2001, with 7.5% growth (500,000 to 1,070,000 tonnes), the decade of hydroentanglement and air-laid growth fuelling the demand for wiping products. Other statistics from the 2001 survey:• Airlaid reached 108,100 tonnes • Wipes reached 151,000 tonnes compared with 57,400 in 1996. Here, the personal care sector used 81,000 tonnes and the household/industrial sector used 70,200 tonnes - down from 73,900 tonnes in 2000 due to the economic slowdown. • 2000-2001 market growth was 4.3% in tonnage but 12.7% in area due to the trend to lighter fabrics in hygiene. Industry profitability was however still declining. • Wet laid production had increased to 68,600 tonnes after a long period of stasis. • Bonding methods: 182,200 tonnes of thermal (static), 108,200 tonnes of chemical (declining), 66,900 tonnes of needling (growing) and 99,500 tonnes of hydroentangling (growing) • Compared with the US split of 66/24 short-/long-life, Europe splits 63/27. • Fibres/polymers used: 120,000 tonnes of viscose up from 92,500 tonnes; 228,500 tonnes of polyester which is growing in staple but declining in spunbond; 491,000 tonnes of PP, declining in staple but growing in spunbond; 129,000 tonnes of woodpulp. Asked what would follow wipes as the next growth application, Mr Wiertz mentioned cosmetics (more wipes?) and breathable sports clothing based on fabrics such as Miratec®, Evolon® and Neotis®. The organo-tin scare has had no effect on sales of disposables, but was good for the analytical chemists. European Absorbent Products Krzysztof Malowaniec , a senior VP with Paul Hartmann AG ( Germany ) and the current Chairman of Edana reviewed the European scene commencing with a patent analysis: • In 1999 the leading company published 328 patents, of which 242 were for diapers, 72 for pads and 14 for training pants. • The No2 published 186 patents, 155 of which were diaper related. (20 pads, 7 training pants, and 4 tampons) • Over the 3 years (96/98) the leading company's patents named 1400 inventors, while the No2 had 842 inventors on the same basis. If you listed patents by inventor it was easy to find the most creative individuals in a company. • One person in the leading company had 48 patents on absorbent hygienic disposables. Mr Malowaniec went on to reveal “No1” as P&G and “No2” as K-C, and used a Stiftung Warentest consumer survey of diapers to point out that despite their enormous R&D efforts, diapers from these companies were only marginally ahead of the private-label products in consumer perception of quality. (He estimated 92% of the intellectual property required to make a diaper was now in the public domain.) In the 2002 consumer survey, only 54% rated the brands ahead of private label compared with 60% in 1992. Other changes since a Jan 2000 survey:• The German diaper market has declined by 5% due to the improved diapers being changed less frequently. • P&G's share has dropped from 39 to 32%. • Private Label has increased from 20 to 30% • Training pants had 3% of the market until P&G introduced a better product and since then the market has been growing. In response to questions, K-C do not have a training pant on the German market, “Swiffer” type wipes are growing rapidly, and the demand for biodegradable materials remains almost non-existent due to lack of composting infrastructure. European Diapers and Wipes Market Sabine Martini of Smartini ( Germany ) provided an assortment of 2001 market statistics: • 64% of WE diapers were branded. Some producers sell into both branded and private label sectors. • Private label diaper share varied from about 50% in Germany and the Netherlands to 15% in the UK and 12% in Italy . • Europe uses 81,400 tonnes of baby wipes along with 35,900 tonnes of industrial wipes and 34,300 tonnes of household wipes, according to EDANA. • P&G had the largest share (~30%) followed by private label (~28%), J&J (~20%) Beiersdorf (~5%) and “others” (~13%) • In the UK in 2001, J&J lead the baby wipe sector with ~40% share, P&G had ~25%, the remainder being private label and others. • In Germany private label led with ~35%, J&J had ~25%, Hartmann ~5%, leaving the remaining ~30% split equally between P&G, Nestle, and “others”. In estimating the theoretical baby wipe market demand and the current penetration of disposables, Ms Martini assumed 2 wipes per diaper change, admitting that while this was more than actually used on baby's bottom, it was justified by the other uses to which these wipes were put. On this basis the theoretical German market was 5.7 billion wipes and the 2001 penetration was 56.3%. The figures for Western Europe as a whole were 33.8 billion wipes and 49.4%. Recent Innovations: Implications for Suppliers Future hygienic absorbent products would be ultra-thin, body-conforming, cloth-like products which controlled odour, promoted skin health and were environmentally friendly according to Pricie Hanna of John Starr Inc.• Thinness: as exemplified by K-C's new “Huggies Pull-Ups”, would need over 55% of SAP in the core. Other products mentioned were Ontex “Hybatex” technology, K-C's “Poise Pantiliner”, SCA's “DriActive Liners” and “Serenity Slender”, and Hartmann's “Ria Ladycare”. • Body-conforming: as in P&G's “Pampers Custom Fit Cruisers” and “Pampers Easy-Ups” using an apertured card/thermal-elastic film laminate, or in K-C's “Huggies Supreme” with a Spunbond/elastic filament/spunbond laminate. • Cloth Like: as in P&G's “Pampers Swaddlers” and “Pampers New Baby”. Fine PP fibres made from Atofina's metallocene resins could make softer coverstocks. • Healthy: as in Mabesa's hypoallergenic diaper with “ProDerm” or J&J's “Carefree super-thin ventilate” pantiliners on the market in China . • Odour Control: as in SCA's “Odasorb Plus” in “Serenity” or Ontex's “Active ODS”. • Environmentally Friendly: P&G's licencing of it's “Nodax” biodegradable polymer process to Kaneka to allow films, fibers and nonwovens to be made available. P&G anticipate a 50,000 tonne/year demand. Cargill-Dow's “NatureWorks” PLA and Eastman's “Eastar Bio” are other contenders. Thong, micro and black pantiliners, youth diapers (for enuresis), swim diapers and K-C's semi-durable beach blanket were examples of new products meeting unmet needs. Advanced leakage protection was exemplified by Tampax “Pearl” tampons and Kao's “Leak-Free” adult diaper with absorbent leg gathers. Increased links between basic material suppliers and the major converters were noted, e.g. the P&G/Equistar Chemicals collaboration on elastic polypropylene from the metallocene route. Asked about wet-toilet tissue, Ms Hanna felt K-C must be disappointed with progress to date, unattractive presentation to the consumer being part of the problem. The lack of progress of pre-formed cores, (femcare, light incontinence and swim diapers apart) was felt to be due to the major economic consequences for converters who would have to re-equip to use the preformed product effectively. Apertured films and nonwoven topsheets seem to have reached equilibrium in femcare: women preferring one or the other, and some products now using both. Wipes Market Developments Lynda Kelly of John R Starr Inc surveyed the wipes market: • Global growth at 5% to 7.7 billion m2 expected through 2006. This will require an extra 1.5 billion m 2 of fabric (or 90,000 tonnes at 60gsm) mainly hydroentangled. • Hydroentanglement will grow at the expense of airlaid due to a major converter deciding to switch. • Airlaced (pulp/cardweb laminate hydroentangled) is not yet accepted in the US wipes market. • Needlepunched fabrics will grow in the washcloth/bathing towel sector. • New US HE capacity has been announced but imports from Europe and the Middle East will continue to satisfy growing demand. • Personal care wipes account for 55% of the 2001 global total, Industrial 32%, the remainder being homecare. • The key companies in “cleaning”, P&G, Unilever, Colgate Palmolive and Reckitt & Benckiser will grow their wipes businesses by developing the wipe delivery system for brands that do not currently use wipes. • Companies yet to employ the wipe delivery system to any extent will also become nonwoven customers: e.g. Estee Lauder, Sara Lee, J&J (non-baby-care), Revlon, Dial, Gillette, Church and Dwight, Schering Plough. In response to questions:• Baby wipes will continue to grow: more will be used per change due to their increasing use in other baby- and adult- cleaning tasks. • Geographic growth to be expected in South America first. • Air-lace will grow as wipes enter the cost-reduction phase. • Wet toilet tissue is still a growth opportunity, but not in the form of the recent K-C product. Real Nanofibers at low cost Evan Koslow of KX Industries has refined short-cut lyocell using a purpose-built refiner designed to avoid shortening the fibre too much. The resulting 100-250 nm fibrils have sufficient strength and length to be wet-processed into filters. Such filters can intercept bacteria whilst maintaining much higher permeability than comparable membranes. He currently operates a pilot system making 10-15 lbs/hour of the nanofiber, but will have a 250lb/hr capability in 6 months and a 2000 lb/hr unit a year from now. The highly self-bonding fibrils form much thinner HEPA filter paper at higher strength and with equivalent particle removal efficiency to conventional epoxy glass products. (The test used 0.18 micron dioctyl phthalate droplets at 32 liters/min through a 100 cm 2 flat sheet). Being 0.16mm thick c.f. the equivalent epoxy-glass at ~0.4mm, the nanofiber paper can be pleated to pack more area into a filter frame yielding 25% lower pressure drop and higher dirt holding capacity. For water filters, the nanofibers are blended with a few percent of bico which is melted without calendering to give a relatively permeable wet-strength paper. (1 litre/sec/cc at 40 psi differential pressure: high c.f. membranes of similar pore-size) When used in conjunction with an active carbon “protective adsorbent”, a 50 cm 2 piece of an antimicrobial-treated nanofiber paper can process 90 litres of contaminated water (over 6 days, gravity fed with a small hydrostatic head) before its viral reduction performance declines below 4-log. The cost of such a filter was put at 3-4 cents. Dr Koslow believes a few percent of low-cost nanofiber based on lyocell would, when added to diaper-pulp, greatly modify the wicking properties. It would also cause dramatic changes in the capabilities of precoats such as diatomaceous earth. In response to questions: • Nanofibres in fluff pulp would reduce odour by reducing bacteria. • A paper machine has to be extensively modified to cope with the <50 CSF slurries. • The electrospinning route to nanofibers will be unable to reach the productivity of the refining approach. • Nanofiber air-filters fail when dirt capacity is reached. • Nanofiber water-filters fail when the active-carbon protective layer breaks down. • The bubble point for the 0.35-micron mean flow pore size is due to a 1.8 micron pore. Nevertheless the paper would intercept 99.9% of 0.35-micron particles. Even Cheaper Lyocell Nanofibers Calvin Woodings (consultant) described how to make a highly fibrillating version of lyocell and pointed out that it would be cheaper than the current textile versions. Furthermore the fibrillation would not be a problem in most products: Soft-touch textiles rely on fibrillation for the effect. Classic finished textiles need to be cross-linked to give them wash stability. The same cross linking may also stabilise a highly fibrillating fibre. No disposable products would suffer from fibrillation problems. Suede-like and micro-fibre wipes would be possible at lower water pressures through hydroentanglement bonding. High performance filters – including cigarette filter-tows - could be made with much less fibre refining. The nanometer-scale microfibrils in lyocell could be liberated much more easily than at present. Mr Woodings described highly fibrillating lyocell as the ultimate islands-in-sea bicomponent fibre, with millions of crystalline nanofibres floating in a sea of potentially-dissolvable amorphous cellulose. He suggested that current lyocell was proving to be a niche fibre, unlikely ever to reach the scales predicted by the pioneers because of it's relatively high price. The key to further growth was to think nonwovens rather than textiles. He suggested future investment should be in a “2 nd Generation” lyocell process using lower-capital, larger-scale plants to make a basic fibrillating fibre that would be fine for mainstream nonwovens and could be cross-linked for the lower-volume critical textile uses. Superabsorbent Composite forms acquisition layer in use Evan Koslow said his KX Industries company makes an active carbon filter element (PLEKX™) by bonding the carbon particles with “microdots” of hot melt adhesive at a level that hardly reduces the active surface area. KXI has now done the same with superabsorbent powder and can make a highly porous 100% SAP sheet that does not gel block. The hot-melt particles are 1/20 th the size of the SAP particles. When sandwiched between a suitable cover (tissue or porous spunbond mentioned) and backsheet (tissue or non-porous sheet) the composite swells with minimal X-Y spreading on wetting. One particular grade of SAP surprised Dr Koslow's researchers by spontaneously forming a 3 dimensional array of tubes which filled with fluid prior to its total absorbtion, leaving air-spaces in the swollen pad. This allowed the 100% SAP layer to capture large insults in a few seconds prior to the usual slow absorbtion by the polymer. The hollow tubes in the SAP are 4-8mm in diameter and appear to form as one side of the laminate swells causing curls and twists. They have minimal integrity and are easily crushed. A 1mm thick layer of the bonded SAP under two acquisition layers has been compared with a branded diaper and a conventional incontinence pad in MTS-TEFO testing. Under compression in the test machinery, the KX-SAP was 0.065” thick compared with the ~0.2” pad/diaper thicknesses. 100ml fluid was applied in 7 seconds and the overflow levels measured. The KX-SAP composite outperformed the inco-pad (12 mls versus 31 mls leaked) but was slightly worse than the diaper (13 mls versus 9 mls.) In response to questions: • Do we buy or make the SAP composite? It would be best made in-house next to the diaper line. • The hot-melt is evenly applied to the SAP “stochastically due to electrostatic charging”. • The process is heavily patented. • Multilayers of the SAP would be better than one. • The laminate is not stiff. The flexibility of the outer “tissues” defines stiffness. • Rewet and multiple insult results will depend on the coverstock used. 2 nd and 3 rd insults are excellent because the tubes are still open. • The tubes will certainly collapse under baby's weight. • KXI's PLEKX™ process can convert 10,000 tonnes/year of SAP into laminate. • Surface cross-linking was “special” for the first product. Hydroentangled 100% Pulp or Thermal bonded 100% Synthetics Henning Skov-Jensen of M&J Fibretech described trials to entangle 100% pulp, both with and without a tissue carrier. • 60-1200 gsm pulp can be entangled without a carrier; down to 8gsm can be entangled with a carrier. • Untreated pulps give the best wicking: 25-30 cms after about 10 minutes. • Absorbent capacity drops from 9 to 6 gms/gm as entanglement pressure increases. • Treated pulps give the best tensiles: at 200 gsm MD tensiles ranged from 10-15 N/5cm, and CD's from 6-14N/5cm. MD Wet ranged from 2-4 N/5cm. • 150 gsm pulp could be entangled at higher energy to get 25-33 N/5cm in the machine direction. Latex bonding would triple/quadruple these figures and addition of synthetic fibres, even without thermal bonding, would also give a useful strength boost. Here 20% of 6mm lyocell gave the best tenacities at 80N/5cm, and also enhanced the final absorbency. However the best strengths of all came when 20% bico fibres were melted. Mr Skov-Jensen introduced 100% synthetic air-laid high-loft, high resilience nonwovens of a wide range of basis weights for use in waddings and acquisition layers. In response to questions, up to 25% of the pulp could be lost through the wire in hydroentanglement, but 15% was more typical. Even at this level, 100% pulp HE was said to be commercially viable. The use of a carrier could reduce pulp loss to about 4%. He claimed to have hydroentangled 400 gsm webs - but did not comment on the commercial viability of this. Hydroentanglement of Thermal Bonded Spunbonds Daniel Feroe of Rieter-Perfojet described work reminiscent of the BBA approach to bulking fully formed textiles by passing them through a hydroentanglement machine. Taking advantage of the fact that their new spunbond pilot line can feed directly into their hydroentanglement line, R-P has explored the effects of water jets on a fully calendered spunbond. Point bonded PP nonwovens in basis weights from 17 to 60 gsm were processed under undisclosed conditions. The hydroentanglement process, as expected:- • Doubled the thickness of the 60 gsm product and added 30% to the thickness of the 17 gsm.fabric. • Bending lengths were halved at 60gsm, the effect diminishing with basis weight similarly to thickness. • Tensile strength was 30% down at 17 gsm and 15% down at 60gsm. However this was on the basis of MD+CD results. • CD tensiles were increased (from 26 to 33 N/5cms at 20 gsm) • The HE'd fabrics looked more even and felt better than the controls (no jet-lining, presumably due to the fact that the point bonds survived the treatment) Just as air-jet texturising can make a filament yarn feel more like a spun yarn, spun-lacing a spunbond makes it more like a carded thermal bond. Despite the strength losses, the HE'd spunbond remains stronger than the equivalent carded product despite being at least 50% thicker. It also emerges with higher CD strengths and higher elongations than other spunbonds. Mr Feroe estimated the spunlacing could be done on a spunbond line for an additional $0.05/kg. The process was not yet commercial, he had not yet tried spunlacing SMS structures, and while hydrophilic spunbonds could be treated, we guessed they would emerge hydrophobic, and need refinishing afterwards. USA 's first fine-denier spunbond Stuart Smith of American Nonwovens Corporation described their experiences since the 1997 decision to install their first fine-denier spunbond line. This system accelerates the filaments to higher velocities at laydown, and hence allows more orientation to be developed and, if required, finer filaments to be produced at higher productivity than on conventional machines. In principle, the technology should, from a single beam produce something with a cover factor equivalent to an SMS. Furthermore, it's ability to accelerate filaments up to 8000 m/min should allow it to run a wide range of polymers, including nylon, polyesters and polylactic acids. The higher orientation leads to improved fibre properties and hence nonwovens with higher strength, lower extensibility and reduced heat shrinkage. In practise the American Nonwovens line has successfully produced 24-50 gsm nonwovens at an MD/CD of 2:1 from PP, PET or CoPET (Eastar Bio) polymers with filament deniers from 0.9 to 1.5, giving a basis weight uniformity of +/- 7.5% across the width. These have been successfully tested and accepted in various markets but not released for sale because American Nonwovens feel this range is too limited for their purposes. A major machinery upgrade is now underway in collaboration with the machine supplier, who will redesign and re-engineer to achieve: • 10-120 gsm fabrics • at 0.5 to 4 denier • with an MD/CD of 1.2-1 • using a wider range of polymers • to give a uniformity better than +/-5% The line is now expected to be competed in mid-2003, 6 years after commencement of project. American Nonwovens want the line to make speciality, high performance products for niche markets, and clearly the first iteration could not do this. In particular they are targeting barrier materials with higher air permeability and hydrostatic heads at lower basis weights than SMS, and filtration products. In response to a question, they have not run PLA on the line. Reicofil 4 Detlef Frey of Reifenhauser promoted the latest version of their spunbond machinery. The main improvement over Reicofil 3 relates to it's ability to process polymers other than polypropylene, especially polyester into fully crystallised polyester filaments (i.e. laydown at >5000m/min). These would have a tenacity of up to 33 cN/dtex (sic) with a boiling water shrinkage of less than 5%. For polypropylene the main advantage would be higher potential throughput or the ability to make finer deniers Asked if a Reicofil 3 line could be fitted with the improved Reicofil 4 cooling, stretching and laydown system, Mr Frey thought not because the new system required 5m depth per beam compared with 4.4m available on the “3” system. No “4” lines were yet running commercially but two were scheduled for start-up in mid 2003. He did however claim to have installed a total of 125 lines (270 beams) of the earlier systems, in 30 different countries. Reicofil 4 worked well with polybutylene terephthalate. Diamond Technology Tom Daugherty of P&G positioned the stretch-apertured nonwoven (“SAN”) technology, now available for licence, as a spin-off from years of studying the failures around point-bond sites when producing stretchable diaper components. They had learned how to make bonds fail on demand by designing them to be the weakest link. So, if a thermal bonded nonwoven was embossed with intermittent lines and then stretched by passing through interdigitating grooved rollers (ring-rolling) the lines became apertures in a regular pattern defined by the embossing pattern, while the original thermal bonding pattern, and hence the fabric strength, survived. Fabric widths could be doubled (basis weights halved) in the process and the resulting nonwoven would be considerably softer, more porous and more flexible than the original. Apertures of the highest clarity (no fibres crossing the hole) and with lint-free edges could be up to 30mm in diameter, and total open area could be as much as 70%. The process also allowed lamination of multiple layers of nonwoven. Patent protection is of course available: USP's 5628097, 5658639 and 5916661 being listed. In response to questions: • Most nonwovens can be apertured: there are few limitations. • The pilot line at P&G is 355mm wide. • Two nonwoven producers are already operating the process on a commercial scale. • Wipes are among several areas where this technology will allow unique products to be produced. • The line will operate at speeds to allow on-line use in any current nonwoven production process. Spike forming Carsten Andersen of Formfiber Denmark ApS positioned his Spike airlaid nonwoven former as a high productivity waste recycling machine capable of making a wide range of bulky waddings from a wider range of raw materials. Inputs could be trim-waste, scrap, cut-outs etc from the hygiene, medical, textile, carpet, paper and automotive industries. The machine would handle any fibre length from dust to 75mm. Outputs could be 10-5000 gsm in thicknesses up to 40cms. At 1000 gsm a 1 meter wide former would consume tonne per hour of raw material. Hammermilled wipes production waste has been processed into 250 gsm white boards. Mixed textile and carpet waste including foam has been processed into thermoformable sound absorbing boards for use in automobiles. Cleaner fibres could be made into 5000 gsm webs and through air bonded if 10% bico fibre was added. Cotton and cotton waste had also been processed. Diapers for the Third World ? Rich Chapas (Consultant) argued the case for really low-cost disposables made locally to allow the world's “base of pyramid” consumers to enjoy their benefits. The target market would be those on incomes of under $1500/year, most of whom were without power or clean water. Successful examples of “base of pyramid” marketing were nutritional products and the provision of mobile phones (one per village) to allow commerce to start. Nonwoven sales were admittedly a few years away but water-purifiers, femcare and constructional composites were possible starting points. An in-country entrepreneur and a multi-national company prepared to take the long-view were necessary to get going. Diapers for the Third World – Part 2 Bill Ouellette of Chlorox Services Company, formerly with Procter and Gamble, emphasised that Chlorox was not interested in the diaper market, and gave the paper originally intended for May 2002's NTC conference in Ottawa. In a nutshell he argues that if 1960's style (and performance) diapers were made with current advanced materials and conversion machinery, they would be so cheap they could be sold in markets where diapering does not yet exist. This, he thought, was the only way to grow the diaper sector at any reasonable rate in the next few years. The target price to open up this market, defined as the population of the third world on $3300/year or more, must be less than 4 cents per diaper, c.f. the 21 cents for today's economy diapers in the USA. Other points of interest: • The billions spent on making near-perfect diapers a little better is now reducing revenue. Diaper usage is declining as they are worn longer. • A Z-fold diaper made of tissue paper with plastic back could meet the price target. • Cover/core/backsheet composites formed on an air-lay line would come close. In response to questions: • Small companies producing such diapers locally would do better than the multi-nationals. • The new diapers would not replace cloth diapers: diapering would be a cultural change for the target population. Is your period really necessary? Ruth Zielinski of Childbirth and Womens Services PLC thought women would soon be electing to reduce the frequency and/or intensity of their menstruation, or even to eliminate it altogether. Options include: • Taking oral or non-oral contraceptive hormones continuously until it is convenient to have a period. • The new Seasonale™ pill will be marketed on the basis of a period every 3 months. • Patches (e.g. Ortho Evra™) or vaginal rings (e.g NuvaRing™) containing hormones are normally omitted once a month to allow menstruation, but can be used more or less continuously. • An intrauterine device (Minera™) can be left in for up to 5 years. While using this total flow reduces and after one year, 20% of women have no period at all. • Removal of the endometrium altogether causes 62-74% of women to stop having periods and causes flow reduction in the remainder. The “ablation” procedure takes 10 minutes as an out-patient procedure, and most women can be “back to work” in 3-4 days. • Extreme exercise suppresses menstruation, apparently without any harmful side effects – assuming pregnancy is not required. Femcare materials: Needs and Insights John Poccia gave a personal view of femcare materials having pointed out that his views were not necessarily those of his employer, Johnson and Johnson . During an overview of the female anatomy, menstruation and markets, the following points were notable: • Peak pressure on a tampon would be 100mbar • Highest “normal” recorded fluid loss was 42 g/24 hours (day one). Typical values for the first two days were 10-20g/day. • The fluid is shear-thinning and does not clot. • A lot of fluid remains in a pad's acquisition layer: better cores are needed. • Additives to pads (protein cleavers) can reduce the fluids viscosity to aid its absorbtion by the core. With regard to the market: • The US market (2001) uses 26% thickpads, 14% thin pads, 30% liners and 30% tampons by volume. • Nonwoven and apertured film covers have equal shares of the pad market. • Winged pads have 45% of the pad market. • 45% of liners are used only between periods, and 15% are used only during periods. The remainder is classed as “dual usage”, which seems to mean that 40% of pantiliner users use them all the time. • Thong, black and micro products were growing most rapidly. • J&J is marketing Carefree™ in China with a spun-laced cover and core to get maximum “textile-like” quality. • P&G and J&J together make 75% of the world's tampons. • 9% of US tampons are digital, the remainder being equally split between plastic and paper applicators. • Only 10% of German tampons use applicators whereas in the UK , 45% are digital. • The fastest growing tampon sku is the multipack system. • While innovation in tampons has been minimal over the last 60 years, P&G's Rely™ was truly innovative and the best performing product. But for TSS all tampons would now be made like this. It had high capacity, freedom from leakage and was very comfortable to use. • Innovation was clearly still possible in this category: target – the properties of Rely™ without any TSS connotations. • Materials used in external protection would “spill over” into tampon designs. • Tampon patenting has been rising over the last five years. In response to questions: • Interlabial products avoid the TSS issue but still have design problems. Superabsorbents were not required: product design was the key issue. • P&G's Pearl™ tampon is “incremental” rather than revolutionary. • Would 2 different ADL's help in absorbing the 2 phases of the fluid? No. • The driving forces in pad and liner design will be ultrathin and textile-like. 100gsm cores with acquisitive coverstock Jim Hanson of MTS continued his crusade for pre-formed diaper cores with part three of the series: • 400ml absorbent core capacity is unnecessary: 100ml would do. • 100 gsm bico/SAP core with cover and back would be adequate c.f. 600gsm now. • 90% SAP would be possible in these lighter structures. 50-70% would be used in practice. • Waterproofed wet-strength tissue paper could be the backsheet. This could also be air-laid. • Multiple layers of lightweight cores would be a better way of reaching higher absorbency • SAP's would not have to be surface cross-linked for high retention under pressure. The resilient bico-structure would provide this. • The ability to use really different superabsorbents would allow newcomers to avoid existing patents. • Diapers would need redesigning to get the best out of the new cores. Wicking tests, and diaper testing on live consumers remained to be done. Testing Food Pads Genevieve Beland of Lysac Technologies (Canada) pointed out that the absorbency test methods used in the food industry are a) not standardised and b) do not reflect the performance-in-use of food-pads. In particular: • The use of 0.2% saline or even tap water to test absorbency gives very different results to the exudates e.g. from chicken. • Pads have to work at lower temperatures than testing temperatures. • Pads are often in use at a 45 degree angle on supermarket shelves. • Stacking during transport increases the pressure on the pad to at least 0.3psi. Lysac therefore developed a synthetic exudate to simulate the high viscosity, protein and salts content of real exudates. They also standardised on a 30 min dunk followed by a 10 minute horizontal drain, for the TFA test, and a 24 hour soak under 0.1 psi at 4 0 C for the AUL test. For retention they applied 0.3 psi in a centrifuge. These methods showed their Safe and Natural Absorbent Polymer (SNAP) performs just as well as the cheaper “synthetic” SAP's . Ms Beland would not reveal the chemistry of SNAP beyond saying it was a polysaccharide. The Jewel in the Crown? Andrew Urban – Consultant listed the problems facing the start-up hygienic product producer: • Higher materials cost due to less powerful purchasers. • Minimal R&D expenditure. • Minimal “infrastructure of engineers and technical personnel”. • One plant can't supply nationwide. The solutions to these problems were said to be: • Sole sourcing – admittedly with the disadvantage that this would prevent the buyer from staying in touch with the changes in market price. • Patent analysis: using a patent professional is expensive, so read the magazines, ask suppliers to share their surveys, and maybe use a consultant. • Patent licencing: expensive, but so is defending an infringement suit. • Having a quality control system: “simply the logic of production put on paper”. • Having a process control system such as that used at Pope and Talbot before it was sold to Paragon Trade Brands. Mr Urban felt this last point was the “jewel in the crown” in attempts to succeed against P&G and K-C. Down to the wire? Tom Israel of Albany International has studied the effects of forming-wire weave-pattern on the properties of air-laid nonwovens. Four wires, (two warp- and two weft- faced, each at two different permeabilities) were tested by making 50, 100 and 200 gsm webs from Weyerhaeuser NB416 pulp at 300 inches/min on one DanWeb former. The conclusions: • Web thickness is affected by the wire pattern (and by the basis weight). • Warp-faced wires increased the MD/CD orientation slightly, weft-faced wires had the opposite effect. • The wire pattern is visible on the underside of the webs. • Latex bonding masked the effects. Mr Israel explained that the data would probably not be applicable to a large machine working at higher speeds. He proposed checking the effects of thermal bonding next. High Wet Strength EVA's for Wipes John Parsons of Vinamul Polymers explained that the family of self-crosslinking EVA binders typically used in airlaid latex-bonded wipes gave excellent absorbency and colour but would not give usable structures with wet CD tensiles above 500 g/inch. They were also low in solvent resistance, a point which became important as household cleaning wipes used increasing aggressive lotions. This strength could be improved with external cross-linkers, or bico fibres or, if cost and stiffness were not a problem by using more binder. Vinamul had however decided to try to make a better EVA, targeting a 50% improvement in wet strength. The result was their new 25-135A, ready-for-use, 50% solids emulsion which featured a 0 0 C Tg polymer. First trials with 25-135A at M&J Fibertech demonstrated the required 50% strength increase, or strength equivalence to the old binder at 20% lower add-on (16%). Methyl Ethyl Ketone strength was up by 60% but the fabrics were stiffer and the absorbency rate (5 down to 37secs) and capacity (16.4 to 15 g/gm) had deteriorated. Reformulation to improve this had restored the absorbency to acceptable levels while maintaining a 45% strength benefit over the old latex. The new latex can now be used like the old to yield the required improved strength in industrial wipes, or at a 16% binder level to reduce the cost of baby wipe products. If lighter products could be marketed, then at 20% binder add-on, strength equivalence was obtained at 47gsm c.f. the 60 gsm standard. The binder is now in commercial trials in the USA with issues such as wet caliper, loft, extractibles, machine speeds, and wire fouling still to be investigated. The brand name will be Elite ULTRA. In response to questions: • The binder is FDA compliant. • It does tend to neutralise antimicrobials. • There is no wicking data yet. • Vinyl acetate monomer levels are below 1000ppm • It can be foam-applied. • 150 0 C for 2 seconds is needed for full cure. • There is 80-90ppm of formaldehyde in the emulsion. • It costs less than bico fibre to achieve the target strength. • EVA itself is not absorbent. Lamination combining winding Allessandro Celli of A.Celli spa ( Italy ) promoted Celli winders and once again included some details of the hot-melt lamination stage being added, thanks to a collaboration with Nordson, to a full speed slitter/rewinder. This time the possibility of multiple lamination steps leading to the ability to, for instance, stick backsheet to core to ADL was discussed. He thought this was a better way of making absorbent pads on roll than trying to form several different layers on an air-lay machine. Soft Elastic Michael Toal described how Caligen Foam Ltd (UK) has adapted their elastic foam to provide an alternative to conventional elastics in leg-cuffs. The new SoftSeal® product: • Will give a better seal over a larger area, eliminating red marks on baby's legs. This is due to a higher retraction load at 2/3rds stretch giving a better seal over a larger area. • Has >300% elongation at break with <10% creep over 1 hour or <30% creep over 4 hours. • Is available in a wide range of colours, co-ordinated with waist-bands. • Is ultrasonically weldable. • Looks good to mothers. Diaper producers would need a new unwind stand to take the 1metre diameter, 0.8 metre wide spools of 14-50mm wide, ~1.5mm thick foam. The width is typically slit into two on-line to feed each cuff, and this width will be halved at 100% extension. In response to questions: • 16mm foam, stretched to 8mm was used in the Joa trial • Unicharm diapers did indeed use a similar foam in the 1980's “Moony”. The patents have expired. • Spools run for 4-8 hours between splices. • The foam is stable up to 160- 180 0 C so an elastomeric adhesive or sonic bonding can be used. • Caligen's successes to date are not in diapers. • Price? “We feel we can compete”. Multistrand Elastics Greg Hearn of Hyosung (America) Inc., a newcomer to the US diaper scene, reviewed the evolution of diapers from the dawn of time through Victor Mills' invention of Pampers in 1961 to the introduction of leg elastic in the 1970's. Leg elasticity was initially provided by a 0.25 inch low-modulus rubber band about .007 inch thick: the success criteria being containment through even pressure at a level which did not leave red marks on the baby. Multi-strand rubber thread, spreading the pressure over a greater area, did this better than the band, and multi-strand spandex yarns followed. Hyosung produce these and are now trying to offer innovative solutions to the containment problem. Asked if spandex could be available in ribbon form, Mr Hearn thought not. Their spandex shelf life was about a year.

Opportunities Arising from the Fibrillation of Lyocell

TITK 2002 Rudolstadt Germany 4th-5th September 2002,

Please add names as comments

 Pat White - Centre

TITK 2002 Photos

 

 

 

TITK 2002, Rudolstadt, Germany, 4th- 5th September 2002

5th International Alternative Cellulose Conference The event was organised by the Thüringisches Institut für Textil und Kunststoff-Forschung (TITK), and the Materials of Regenerative Resources Research Association. About 100 delegates from 10 countries attended. The conference was distinctly less international than its predecessor: no Japanese and only one Chinese delegate. Summary of Key Points • Lenzing expect a 700,000 tonne lyocell market by 2050. • Silyl cellulose developed by Rhodia can be melt-spun and hydrolysed back to cellulose. The technology is for sale. • Weyerhauser's cheaper Kraft pulp is being evaluated by Tencel for use in nonwovens • Stockhausen has developed a lyocell/SAP alloy fibre with apparently excellent properties and economics. • SAP-filled cellulose beads (3mm) could be an interesting for new absorbent products. • Zimmer is promoting lyocell alginate alloys in textiles for skin-care and “wellness”, wound-care and heavy metal absorbtion. • TITK has spun alloys of lyocell with numerous starches, PVOH, casein, polyacrylic acid, gelatine, CMC's and chitosan. • TITK is now installing a melt-blown/spunbond pilot line (not Reifenhauser) but would not comment on its possible use with lyocell dopes. Lenzing Lyocell Update(G) Dr Harms of Lenzing said the recently announced 20,000 tonne expansion of lyocell production would take their capacity to 40,000 tonnes. Was this sensible when Acordis still has at least that amount of unused capacity? Yes, because Lenzing's strategic market analysis showed a strong demand for special fibres from 2004 onwards, and their Lyocell plant at Heiligenkreutz was already flat out. Furthermore, Lenzing could take a more consistent long-range view of lyocell potential because they were dedicated to cellulosic fibres. Their in-house pulp plant was also being expanded by 35,000 tonnes (to 210,000 tpa), and this facility gave them lower costs than other rayon producers. In particular their recovery and sale of acetic acid, furfural, xylose, magnesium lignosulphonate and caustic soda from black liquor coupled with a policy of transferring pulp to the fibre operations at cost gave them an ability to sell fibre at lower prices than others. Dr Harms claimed they had invested €75M on lyocell, this sum being equally split between dope-making, solvent recovery and fibre production. They were now spending €13-15 Million on R&D: a department employing 130 people currently. They had introduced three new varieties of lyocell, but these appeared to be more marketing than innovation: • Lyocell Micro (0.9dtex fibre) • Lyocell Tech (finished for technical textiles) • Lyocell NW (matt fibre finished for nonwovens) Of more significance was a proposed collaborative project to screen alternative uses for the NMMO solution where around €0.3M would be spent to identify the best area for the next €25-30M investment. A briefly-shown slide giving market projections through to 2050 (not in the printed version) showed viscose staple declining from 2M to 1.7M tonnes, and lyocell increasing linearly from in around 70,000 tonnes in 2004 to 700,000 tonnes in 2050. Lyocell Fibre from Kraft Pulp Mr M Luo of Weyerhaeuser provided data on the properties of lyocell fibre made from Kraft pulp by the process he presented at the 4 th TITK conference in 2000. The presence of 12% hemicellulose in the resulting fibre:- • Reduces strength and modulus by 10-20% • Increases the absorbency (65 to 80% water imbibition) • Increases dye uptake. • Reduces strength loss in dyeing. • Improves absorbtion of triazines (anti-fibrillation cross-linkers) • Improves fibrillation resistance after reactive dyeing • Increases weight loss in enzyme finishing • Increases the diameter change on drying. Lenzing had no interest in the pulp because they make their own lyocell pulp – and this is already cheaper than market pulps. Melt spinning of Silyl Cellulose (G) Dr Ties Karstens of Rhodia Acetow gave the first paper on a new process he claimed made a fibre similar in properties and cost to viscose without the environmental problems. In outline this involved: • Reacting hexamethyl disiloxane (HMDS) with isocyanic acid to form N,O-Bis(trimethyl)carbamate (BSC) • Reacting BSC with ammonia-preactivated cellulose to form the trimethylsilyl cellulose derivative (TMSC). • Melt-spinning the TMSC conventionally into fibre. (250 m/min now, 1000m/min looks possible. While the obvious route to spunbonded nonwovens was not mentioned, a spunlaid web could clearly be made at this stage) • Regenerating (desilylating) the TMSC fibre to cellulose by hydrolysis with 0.1N H 2 SO 4 , recovering 99% of the HMDS. The TMSC can have a DP of 290-790, melts between 240 and 280, and degrades above 300 0 C. It contains 20% of silicon, all but 0,2% being removed in the regeneration process. From the micrographs shown, the desilylation step halves the fibre diameter. (giving a useful denier reduction and an easier route to microfibres?) Asked about fibrillation and absorbency properties, Mr Karstens said they had yet to be evaluated. Lyocell/Polyacrylate alloy fibre(G) Stockhausen has collaborated with TITK to produce an alloy fibre by adding finely ground superabsorbent fibre to the spinning dope. The otherwise conventional polyacrylate-based superabsorbent is subjected to fluidised bed milling to get an average particle size of 5 micron with a maximum of 10. This was injected into dope on the small TITK pilot line to give fibres (4 to 10 dtex) with 5, 25, 33 and 50% superabsorbent content. As the SAP content increased to 50%: • Fibre tenacity fell from 42 to 10 cN/tex. • Loop tenacity ( a measure of brittleness) fell from 10 to 4 cN/tex. • Moisture regain at 65%RH rose from 11.5 to 22% • Water imbibition rose from 60 to 950% in distilled water and from 60 to 410% in 0.9% NaCl. • The fibre cross-section became crenellated (like viscose) and full of large pores (like sponge) Clearly the superabsorbent's collapse on drying leads to cross-section changes, and leaves the air spaces for the SAP to swell into on next wetting. Needlefelt nonwovens were made at Dilo with 0, 50% and 70% of the CLY/33%SAP fibre in blend with polypropylene. Total free saline absorbency of the webs rose from 850% to 1250% as the SAP content increased, and saline retention value rose from zero to 180%. Blood absorbency data matched the saline data. The work will now be repeated on the large pilot line. In response to questions Dr Waldermar Dohrn of BGB Stockhausen had no data on the levels of extract from the new fibres. Lyocell/Alginate alloys (G) Alceru Schwarza GmbH, now a 100% Zimmer company since TITK withdrew, has introduced Seacell®, an alloy of alginate and cellulose, as a high value commercial product from the lyocell pilot line. The new fibres are targeting skin-contact textiles which promote “wellness”, wound-care textiles and films, and fibres for heavy-metal absorbtion from effluents. Dr Zikeli dealt primarily with the latter application here. Silver uptake from a 0.1M AgNO 3 solution is 90-100gms per kg of alginate in 10 minutes of immersion. The silver can be recovered from the fibre by washing with dilute nitric acid, and the fibre reused. Absorbtion efficiency for the second cycle was put at 80% of the first. In a separate investigation where the silver result was 18g/kg Alg. , the fibre absorbed 118 g/kg mercury or 34g/kg lead or 21 g/kg of tin or 16 g/kg of cadmium. While the alginate content was not revealed, the alloy was 10-15% weaker than 100% lyocell both wet and dry, and had similar extensibilities. It does fibrillate and can be refined and made into filter papers. In response to questions, Dr Zikeli could not say whether the alginate used was high in the mannuronic or glutamic form, but did reveal that the alginate did not dissolve in the NMMO. Dissolution would in fact have been undesirable because they need to maintain its ion-exchange capability. In use, some dissolution of alginate occurs at the fibre surface. Lyocell/Starch alloys etc (G) Dr Meister of TITK revealed work on adding starches and other polymers to lyocell dope. While not all of the following were described, one slide provided data on the fibre properties of alloys of lyocell and: • PVOH • Casein • Polyacrylic acid • Gelatine • CMC, both low and high viscosity types • Polyvinyl pyrrolidone, and copolymers • Chitosan The motivation for the work was said to be to improve the dyeability of lyocell (cationic-modified starches carry the necessary N- groups into the fibre). However the addition of 20% of starch could also lower the cost of the final fibre, and, from Mr Meisters data, increase the water retention value from 65 to 115%. The starch-modified lyocell's were said to be stable to bleaching, but attacked more readily by enzymes. Hydrolysis removes the starch content. Ceramic-loaded Lyocell fibres and beads (G) Dr Vorbach of TITK described their process for spinning hollow lyocell fibres, simultaneously filling the tube with a ceramic paste to give a 50/50 ceramic/cellulose bicomponent. The fibres could then be formed into end-products prior to burning off the cellulose coat and sintering the ceramic into fibres. The ceramics could also be uniformly dispersed through solid lyocell fibres. 3mm diameter beads of cellulose could also be made on their “kugelformigen” pilot line and these too could be filled with ceramics. Other materials said to be compatible with lyocell dope were: • Oxides, carbides and nitrides • Perovskites • Alumino-silicates • Lead-zirconia-titanate-based ceramics • Graphite and Metal powders for conductivity • Piezo-ceramics The latter fibres could be used to make “smart” high performance materials, examples of which were: • Helicopter blades and wings which changed shape on demand. • Tennis racquet handles which damped vibration on ball-impact. High-Loft Lenzing Lyocell (G) Lenzing has introduced a 6 dtex, 60mm silicone treated lyocell fibre for use in quilts and pillow fillings. The very slick coarse fibre shows excellent dry-resilience while providing high levels of thermal insulation and moisture transport. With regard to the latter feature, Mr Feilmair claimed a performance better than wool or down and very much better than the cheaper polyester fillings. Surprisingly, after washing, the lyocell-filled quilts dried faster than the polyester-filled quilts. Mr Feilmair also claimed that some customers were reporting that lyocell, even without the silicone finish, was killing micro-organisms, a favourable feature which had to be investigated in more detail. One slide provided new soil-biodegradation data on fibres. Cotton disappeared totally in 20 weeks, and at this point viscose was 70% degraded, lyocell 20% degraded and siliconised lyocell was 30% degraded. Polyester was intact. The siliconised lyocell fibre is apparently selling well, and several independent members of the audience who had bought products containing it spoke highly of its comfort. One questioner working on alternatives to NMMO as a cellulose solvent suggested that the anti-microbial tendency could only be due to NMMO residues at the fibre surface – a point which Lenzing strongly denied. The Synthesis and Properties of Aminoethyl cellulose (G) The methods available to convert cellulose to aminoethyl cellulose were: • Esterification with amino acids • Etherification with amino-organohalides • N-glycosylation • Oxidative C-C splitting and reductive amination • S N 2 reactions of primary leaving groups (O-Tos, O-Mes) Dr Klemm has focussed on the last method, preparing the tosylate by reacting the cellulose with p-toluene sulphonyl chloride in a DMA/LiCl, triethylamine solution. The tosylate on C6 could then be substituted with a variety of diamines. The resulting compound (DS=2.1) could be cast into transparent, elastic and exceptionally smooth film (roughness <12nm by AFM method). It bonded well to glass and was stable to oxygen. The film would immobilise enzymes for medical applications Cellulose synthesis Hiroshi Kamitakahara of the Friedrich Schiller University in Jena ( Germany ) reported the first synthesis of cellulose in 1996. He then used ring-opening polymerisation of a glucose orthopivalate derivate. This proved difficult, so here he focussed on the influence of substituent groups and ring structures on the synthesis of regioselectively functionalised cellulose derivatives. These derivatives could be converted into cellulose if required. A 3-O-benzyl group was shown to be indispensable to obtaining polymers with high stereoselectivity. D.P's of 20 to 70 were mentioned. Structure in blown and cast lyocell films Yaopeng Zhang of Dong Hua University has cast lyocell dope onto a nonwoven prior to coagulation, and has also produced tubular films using a conventional blown-film technique. In this paper he compared their structures. Unsurprisingly, the cellulose film cast onto the nonwoven, being unoriented, had little structure, while the drawn blown film showed more orientation in the MD than TD. Undrawn blown film has more TD orientation than MD. Exotherm reduction(G) Dr Sacchina of St. Petersburg State University ( Russia ) reported that a cellulose solvent comprising two-thirds NMMO monohydrate and one third dimethyl sulphoxide could dissolve cellulose with a lower risk of exothermic reactions occurring to give a better solution than NMMO alone. Other co-solvents studied were formamide, dimethyl formamide and dimethyl acetamide. Sensitive NMMO analytical method (G) Mr A Kolbe of TITK has developed a liquid chromatography/mass spectrometry method for detecting NMMO which is 10,000 times more sensitive than the current HPLC/UV method. To create the ions needed for the mass spectrometry, electrospray ionisation has proved better than atomospheric pressure chemical ionisation because it has less tendency to break up the NMMO molecule. The method, said to be accurate to +/- 3% can detect down to 0.01 mg/kg of NMMO or 0.03 mg/kg morpholine on fibres. (2gm fibre extracted with 250ml water, 25 microlitres of this being used in the HPLC/MS) Structure of Carbamate-route Fibres (G) Dr Fink of the Frauenhofer Institute compared the structure of carbamate, viscose and lyocell fibres. The best carbamate fibres had similar crystalline and amorphous orientation factors to recent lyocell fibre, where early lyocell had been much more oriented. However despite their similar orientation factors, the carbamate route gave about a quarter of the wet-strength of lyocell. In response to questions, the carbamate cellulose fibre had 0.1% of residual nitrogen and was available in 5kg batches from the Institute. Dr Fink said there had been a recent large scale trial in a filament viscose plant. Structure formation in Lyocell Fibres Dr Christian Schuster of Lenzing described work arising out of a friendship with personnel at the Institut Laue-Langevin in Grenoble . A small lyocell spinning machine had been set up to allow spinning into a deuterium oxide bath where a neutron beam from the research reactor in Grenoble could be scattered by the forming cellulosic fibres. The Atomic Institute in Vienna had provided the ultra small angle neutron scattering and detection kit, and measurements had been taken in the air-gap and at three depths in the spinbath. 0.9, 1.3 and 6 dtex fibres had been spun from one-hole and 37 hole jets. The conclusions were: • Thinner fibres contain more (and smaller) internal structure – i.e. macro- and micro-fibrils • Lyocell seems to fit a “structured cylinder bundle” model where macrofibrils of about 1 micron in diameter are held within a thin skin, these macrofibrils being made up of nano-sized microfibrils. • When the fibre first fibrillates, the hairs are macrofibrils or bundles of macrofibrils. • High primary gel-swelling equates to high levels of fibrillation in the final fibre • Fibre structure develops on drying, but is not complete until the 5 th wetting and drying cycle is over. Alkali Dissolution of Cellulose revisited Prof. Henryk Struszczyk of the Institute of Chemical Fibres Lodz ( Poland ) reviewed the methods of “activating” pulp so that it would dissolve in caustic soda alone. Steam explosion as practiced by Asahi and Weyerhaeuser fell short of the requirements for fibre spinning but was usable as food additives. Ammonia pre-treatment (Carbacell®), and the enzyme biotransformation of pulp (Celsol®)were still awaiting commercial backers. A new method of cellulose structure transformation appeared to involve an extension of the Celsol process called “AW” or aggressive water pre-treatment. However Prof. Struszczyk would not define aggressive water, confining himself to saying that the resulting solution had good filterability and could be spun to give a fibre with viscose-like properties. Cellulose concentrations of 7% had been achieved, with 8% being the next target. Sausage Casing Update (G) Dr K Berghof of Kalle Nalo reviewed the market for casings and progress with the NMMO blown-film casings pilot line. They were successfully coating manila hemp and lyocell wet-laid nonwoven tubes with lyocell dope containing 10% of 520DP cellulose on. The dope was cast onto the inflated nonwoven tube prior to immersion in the aqueous spinbath and washing in a three-stage countercurrent wash machine. Glycerine finish was applied to plasticise the structure. It was all looking very practicable and successful, but when asked when they intended to replace their viscose-based casing technology, Dr Berghof said that they would only implement the lyocell technology on a larger scale when forced to by the environmental regulations. Lace production by NMMO dissolution of ground fabrics (G) Some lace fabrics were made by embroidering patterns using polyester yarns on a viscose ground fabric, followed by dissolution of the viscose either in alkalis or with enzymes. Dr Christoph Michels of TITK described their pilot process for dissolving these ground fabrics in NMMO and claimed this route had environmental advantages over the others because it could be run as an effluent free closed system. The lace precursor was dipped in NMMO, heated to 85-115 0 C and then taken through a multi-stage counter-current wash system to remove the solublised viscose. The liquid output of the wash machine at the fabric entry point was said to contain 12-14% cellulose and have a viscosity of 3000-30,000 Pas. The cellulose was precipitated and discarded: the NMMO concentrated and recycled. Hydroentanglement of Lyocell (G) Klaus Volker of Rieter-Perfojet presented data on the spunlace market and the performance of lyocell in hydroentanglement. Spunlacing was said to account for 8% of worldwide nonwoven production or 280,000 tonnes. Of this 33% went to wipes, 20% to surgical, 16% to medical, 13% to industrial, 13% to coating bases, 4% to cosmetics and the remainder to clothing and textile applications. In addition to the now well-established strength and stability benefits of using lyocell (double dry strength and triple wet strength c.f. viscose), Mr Volker confirmed the better clarity of aperturing and watermarking found with lyocell webs. Benefits of Fibrillation Calvin Woodings (consultant) described how to make a highly fibrillating version of lyocell and pointed out that it would be cheaper than the current textile versions. Furthermore the fibrillation would not be a problem in most products: • Soft-touch textiles rely on fibrillation for the effect. • Classic finished textiles need to be cross-linked to give them wash stability. The same cross linking could also stabilise a highly fibrillating fibre. • No disposable products would suffer from fibrillation problems. • Suede-like and micro-fibre wipes would be possible at normal water pressures through hydroentanglement bonding. • High performance filters – including cigarette filter-tows - could be made at lower cost. • The nanometer-scale microfibrils in lyocell could be liberated much more easily than at present. Mr Woodings described highly fibrillating lyocell as the ultimate islands-in-sea bicomponent fibre, with millions of crystalline nanofibres floating in a sea of potentially-dissolvable amorphous cellulose. He suggested that current lyocell was proving to be a niche fibre, unlikely ever to reach the scales predicted by the pioneers. Perhaps the highly fibrillating form should be introduced now in an attempt to try to broaden the market. Ring-spinning lyocell(G) Mr Schwippl of Rieter presented a 52 page manual on how to spin lyocell yarns on Rieter ring-spinning equipment. Finishing Lyocell Fabrics (G) Mr Rolf Brier of Textilechemie Dr Petry GmbH reviewed 10 years of developing finishing technology and finishes for lyocell fabrics. Information from a TITK Tour: A tour of the non-secret parts of TITK was provided for the author on the day after the conference. Key points were: • Excellent small scale needlepunching facilities (50mm Dilo loom) • Wet-lay nonwoven pilot line working mainly on natural fibres for composites. • All the usual chemical and physical testing equipment used by fibre companies • Evidence of shape-modified lyocell fibre work, with trilobal jets being used – but the visible fibre cross-sections were triangular at best. • 10 dtex oval lyocell fibres from 500x50 micron rectangular jets • 500dtex hollow lyocell fibres (dialysis tubes?) • Lyocell fibres filled with ion-exchange resins. • Space was being cleared in the dyeing and finishing hall for a new melt-blowing and spunbonding pilot line. This would not be Reifenhauser technology. Further information, for instance would it convert lyocell dope, was not obtainable. Dr Bauer, the new head of TITK said that following the breakup of their collaboration with Zimmer they have completed a contract with a Chinese group to provide the know-how for the construction of a lyocell plant. They also report that Zimmer are very close to concluding a deal to supply another lyocell plant to a different Chinese group. CRW 11/9/02

Polymer Fibers 2002: Manchester 10-12 July

Highlights• 118 delegates, only 38 of whom were from the UK and 21 from the USA , attended this academic meeting dealing with the frontiers of fiber science.
• Data on the mechanical properties of single carbon nanotube molecules has been obtained by Raman spectroscopy. The molecules were manipulated using an atomic force microscope. The Youngs Modulus is put at 1000 Gpa.
• Atomic Force Microscopy can show the change of surface structure from spherulitic molecules through “shish-kebabs” to fibrils as unoriented PP fibers are drawn.
• X-ray diffraction linked to laser Raman spectroscopy can now give a full picture of molecular and crystal deformation as fibers come under load.
• Polyethylene or polypropylene can be polymerised on the surface of cellulose fibers after grafting on aluminium alkyls.
• TANDEC is studying the dissolution of cellulose from many sources as part of a project funded by the USDA. Melt blown cellulosic nonwoven are one objective.
• 3D shapes are being air-formed from 51mm fibers at UMIST. Applications in disposables are under development.
• Fibers can now be produced with 80% of the theoretical polymer chain strength.
• Work on the structure of the rigid-rod high performance fibers (Kevlar, PBO, M5) is relevant to the understanding of solvent-spun cellulose fiber structure.
• The Japanese project to develop super-strong fibers from commodity polymers is expected to breakthrough in the next year.
• Racemate PLA yields fibers with a 230 0 C melting point. However it will be costly to make this polymer commercially.
• Most fibers will creep-fail at about half their nominal breaking load given extended times under load.
• Computer modelling of polymer molecules to derive the physical properties of fibers made from them is still in its infancy, as is the modelling of fabrics based on fiber properties.

HIGH PERFORMANCE FIBERS

Past and future of high performance fibers E. Roerdink and J van Dingenen (DSM High Performance Fibers, The Netherlands )

High performance polymers are either rigid-rod types (as in Vectra, Zylon, Technora, Twaron, Kevlar and M5) made by spinning solutions of self-orienting liquid-crystals, or flexible chains (Dyneema, Spectra) where the solvent disentangles the long chains to allow crystals to form on gel-spinning.

The rigid-rods came first with Dupont famously spending $700million over 25 years before turning a profit on Kevlar.

DSM (Dutch State Mines) tried to dissolve ultra high molecular weight polyethylene in polar solvents and found fibers forming on a stirrer. Such “surface growing” of fibers was rapidly superseded by gel-spinning, the invention being licensed to Allied Signal for “Spectra”, commercialised in 1986. DSM/Toyobo followed with “Dyneema” in 1990.

Toyobo then developed their own rigid rod approach by reworking Dow's PBO technology to make “Zylon”.

With new super-fibers estimated to require 10 years and $500 million many other attempts were abandoned. Exceptions were Kuraray's KII based on PVOH, the plant being capable of making several other lower performance fibers as well, and M5, picked up by Magellan after Akzo abandoned it.

The current market for super fibers was put at 50,000 tonnes at prices around $30,000/tonne. Aramids had 55% of this, Carbon fiber about 35%.

For the future, watch

Nexia's development of Biosteel, based on milk from transgenic goats – their DNA having been modified with spider DNA to allow spider-silk protein production. (Interesting but unlikely to yield superstrong fibers).

Carbon Nanotubes (see later)

Progress in super fibers in Japan Kazuyuki Yabuki (Toyobo Research Center Co Ltd, Shiga , Japan )

Zylon (Toyobo) matches carbon fiber T800 for modulus and strength and now reaches 80% of the theoretical PBO crystal modulus. Light and chemical stability are being improved.

Technora (Teijin) is an aramid with superior chemical stability and light resistance.

Vecry (Kuraray) is a sheath/core monofilament with a sea-island sheath (PEN or PPS) on a Vectran core.

Kuralon KII (Kuraray) achieves superfiber strengths when the gel-spun fiber is coagulated in cold methanol and stretched near melting temperature to prevent work-hardening.

Dyneema (Toyobo/DSM) was introduced with a 2.9 Gpa strength 10 years ago. It is now 3.9 Gpa commercially and 7 Gpa in the laboratory. 5-6 Gpa looks possible industrially.

All these fibers suffer from relatively poor performance in compression due to weak interchain forces (c.f. the covalent longitudinal bonds). 3D polymers (Cross-linked polyamides mentioned) have therefore been modelled which exceed diamond modulii in all three directions.

Superfibers can be made from commodity polymers (e.g. PET – a semi-rigid-rod polymer). Japan 's Kikutani Project, started this year is expected to breakthough to low cost superfibers in the next year.

One small slide inset, not reproduced in the printed version and not described by the speaker showed a laser heating a very small area of a polyester fiber allowing rapid stretching.

Advances in M5 (PIPD) fiber properties and expectations from fiber theories Doetze J. Sikkema (Magellan Systems International, The Netherlands )

Carbon fiber, being held together covalently, breaks catastrophically, whereas fibers relying on hydrogen bonding fail in a less critical fashion. Aramid strengths have been exceeded by manipulating polymers with no conformational mobility at all – Toyobo's PBO (poly- p-phenylenebenzobisoxazole – “Zylon”) being the best example. However PBO composites fail too easily under compression.

“M5” (PIPD – a polypyridobisimidazole made from 2,3,5,6-tetraamino pyridine and 2,6-dihydroxy-terephthalic acid) developed by Akzo-Nobel corrects this problem by maintaining the rigid-rod structure while adding extra hydrogen bonding sites. The restructuring of Akzo Nobel (acquisition of Courtaulds and the formation of Acordis) led to this project being abandoned, Magellan Systems International being formed to commercialise it using the A-N equipment. Composites made from the fiber demonstrate much improved impact resistance, damage tolerance and wear resistance than those using carbon fiber. UV stability is also unusual, the effects of long exposure, having if anything a slight strengthening effect on the fiber. (The molecular similarity between PIPD monomer and UV stabilisers was invoked to explain this.)

Fiber theory: The strength of fibers Maurits Northolt (Acordis Industrial Fibers, Arnhem , The Netherlands )

Fiber breakage under load is the result of shear failure brought about by the imperfect orientation of the fibrils, crystals and polymer chains within the fiber. All fiber elongation is due to shear between fibrils and within crystals, chain stretching being negligible. Fibers of different strengths from the same polymer all fail when extension reaches the hyperbolic shear-failure curve. Cellulosic fibers have more in common with the aramids and other rigid-rod polymers than with the thermoplastics. The strongest fibers will have the lowest elongation and highest initial modulus. Other factors of importance are:

• Impurities and flaws in the fiber
• Cross sectional variations
• Creep (i.e. Time)

The time effect is much more important than generally understood. Given much longer loading times than used in tensile testing, most fibers will fail at about half their nominal breaking load. The latest high modulus fibers (Such as Magellan's M5) have 4 inter-chain hydrogen bonds where the aramids have only 2.

Mechanical analysis of high-performance polymer fibers and the consequences for end-use A. Schaap and J. van den Heuvel (Teijin/Twaron, The Netherlands )

Mean strength less 3 standard deviations is a better predictor of composite strength than the normally-used mean strength. Single filaments have the same strength whether twisted or untwisted unless the compression forces go above the critical point.

(no printed version)

Deformation mechanisms in single fibers R. J. Young, C. Riekel, M.M. Moran, R.J. Davies (UMIST, Manchester , UK )

Synchrotron X-Ray diffraction using the micro-focus beam line at ESRF has been used to study changes in the structure of PBO filaments as they come under load. A 3µ X-ray beam had been stepped across the 12µ diameter fibers in 2µ steps. Three types of PBO, the AS (as spun) the HM (higher modulus by heat treatment of AS) and HM+ (ultra high modulus from non-aqueous spinning) were used. When linked with parallel studies using 2µ laser Raman spectroscopy, a full picture of both crystal and molecular deformation of fibers was obtained. (No printed version)

Stress distribution in PBO fiber as viewed from vibrational spectroscopic measurements under tension T. Kitagawa, K. Tashiro, K. Yabuki ( Toyobo Research Center , Shiga , Japan )

Unlike Kevlar, PBO has a lower fiber modulus than expected from its crystal modulus. Raman spectroscopy of fibers under load fitted a hypothetical mechanical series/parallel arrangement of crystals and amorphous regions. It was concluded that PBO must have small amorphous regions between the crystals. These must be eliminated to get the maximum strength. (This appears to be achieved in the HM+ version mentioned above).

MECHANICAL PROPERTIES

Ex-situ and in-situ observation of polypropylene fibers using advanced microscopy techniques O.K. Risnes, R.R. Mather, A. Neville, J. Buckman ( Heriot-Watt University , UK )

Scanning Probe Microscopy (SPM) comprises Atomic Force Microscopy (AFM) which measures the vertical movement of the probe due to atoms at the surface, and Lateral Force Microscopy (LFM) which measures the lateral movement of the probe. The technique has been used to study the development of structure during the melt extrusion and drawing of PP. Spherical molecules on the surface of the undrawn fibers can be seen to change to “heavily deformed spherulites”, shish-kebab structures and fibrils on drawing.

PA 66 high performance fibers: Microstructural mechanisms responsible for their mechanical properties during loading and fracture A. Marcellan, A.R. Bunsell, R. Piques, Ph. Colomban (Ecole des Mines de Paris, Evry , France )

The use of µ-Raman spectroscopy showed that the PA66 fibers have a skin-core structure leading to the outer few microns experiencing different stresses to the core when the fiber is loaded. Wide-angle X-Ray diffraction shows that the orientation of the amorphous regions increases under load and makes an important contribution to the modulus below 5% strain.

Fiber transverse deformation and cut performance of protective apparel Warren F. Knoff (Du Pont Company, USA )

Cutting is very rapid transverse abrasion under very high pressure. Cut resistance of a fiber has nothing to do with fiber tenacity but is related to the work required to deform the fiber in the transverse direction (TDW – transverse direction wear). This can be assessed using the Kawabata compression test where TDW is defined as the area under the compression curve when the diameter is reduced by 30%. The TDW results for Kevlar correlate well with the cut resistance measured on an auto-cut tester.

• Continuous filaments are harder to cut than staple: a feature explained by crimper damage during staple manufacture.
• Drier fiber is harder to cut.
• Heat treatment improves cut resistance up to 250 0 C (Kevlar)
• Higher deniers are harder to cut: a feature explained by the less ordered structure of higher denier versions of Kevlar.

Numerical modelling of the tensile behaviour of fibers with geometrical and structural irregularities W. He, X. Wang ( Deakin University , Victoria , Australia )

Computer modelling of fibers with varying cross section and small cracks in the surface showed that fibers would break at their weakest point. The graphics were pretty though.

Progress towards first principles modelling of the mechanical properties of fibers G.R. Davies (IRC in Polymer Science & Technology, University of Leeds , UK )

Attempts to derive fiber properties from computer models of polymer molecules are still years away from delivering useful results. Some progress has been made in predicting the Raman shifts from a cellulose molecule under load.

The initial modulus of fibers - intrinsic or not? N. Pan ( University of California , Davis , USA )

Breaking load increases and elongation decreases as the length of fiber under test is reduced. Dr Pan's work showed that the modulus also changed with gauge length: shorter fibers becoming less stiff in extension. Despite the fact that during his talk he had addressed all the factors where errors might have led to this result, he was thoroughly put down by the moderator who insisted that modulus does not change with gauge length, and that his findings were due to fiber slippage in the clamps.

PROCESSING

Fiber structure development in high-speed melt spinning of polylactides Takeshi Kikutani (Tokyo Institute of Technology , Japan )

Racemate Polylactic Acid (r-PLA, made from equal parts of polymers produced from L- and D-lactides) crystallises well to give a fiber with a melting point of 230 0 C c.f. 170 0 C for the current PLA polymer based on mainly L-lactides (PLLA). The stereocomplex crystals formed from r-PLA were however shown by WAXS to be “contaminated” with a -crystals from the L-lactide. The a -form could have arisen in the cooling process after annealing above the melting point of the a -form. The r-PLA had nevertheless been spun into fiber at 7km/min demonstrating improved structure and shrinkage compared with the commercial form of PLA. Orientation-induced crystallisation occurred at 4km/min for the r-PLA c.f. 5-6km/min for the PLLA.

Asked if the presence of the a -form crystal was perhaps due to the polymer mixture having a slight surplus of the PLLA, Dr Kikutani had thought this may be the case but was prevented from analysing the sample from Cargill Dow by the terms of the sampling agreement. The r-PLA was thought to be very expensive. (It could not be made from a 50/50 mix of the monomers but required 100% PDLA to be mixed 50/50 with 100% PLLA)

A new concept for self-reinforced polypropylene composites J Loos, T. Schimanski, P.J. Lemstra, N.O. Cabrera, B.Alcock, T.Peijs ( Eindhoven University of Technology , The Netherlands )

Problems with recycling glass-reinforced PP composites led to this work to develop an “all PP” co-extruded tape composite of similar strength. A high modulus isotactic PP core polymer is covered with a lower-melting PP copolymer sheath, the whole being crushed at the copolymer melting temperature to form the composite.

Failure analysis on the composite shows that the bonds between the sheaths are stronger than the interfibrillar bonds in the homopolymer core. While the stiffness of the all PP composites was inferior to the glass reinforced controls, impact studies showed the all PP product to be superior. It showed less damage after a 30joule impact than the GRP showed after a 15 joule impact. Future work will involve other polymers than PP. Asked about compressive and flexural strengths, Dr Alcock said these had yet to be measured. The questioner pointed out that glass has the same modulus in all directions whereas any man-made polymer would always have poorer properties in the transverse direction.

Processing and biorelevant characterization of fibers from bioerodable, polymeric biomaterials Mike Jaffe ( Rutgers University , New Jersey , USA )

Bioerodable polymers degrade in-vivo, serving as a temporary scaffold to establish growing tissue. They are made in 20gm lots by the biomedical community, a group with no understanding of fiber science. Prof. Jaffe has been studying the 100+ “library” of polyarylates in fiber form to see how their structure could affect the polymer/biological interface. He concluded that the “library” is not simply a group of amorphous polymers with systematic Tg behaviour and surface properties. They showed complex melting behaviour and were “replete with nanostructure”. He was now searching for the biological impact of such properties.

Thermosetting of partially crystalline fibers: temperature-time effects and a predictive model D.R. Salem, N. Vasanthan (TRI/Princeton, New Jersey , USA )

Filaments of nylon 6, 66 and polyester were twisted, heated, cooled and then assessed for residual twist as a measure of heat set. The variables studied were heating time and temperature, the moisture content of the fibers and their microstructure. Time emerged as a major variable, equivalent to temperature: similar setting could be achieved at lower temperatures by holding the twist in for longer times. Equations have been derived which allow the prediction of the degree of heat setting for any combination of time and temperature.

Elongational rheology of fiber forming polymers J. Collier, S. Petrovan, P. Patil, B. Collier ( University of Tennessee , USA )

Elongational Viscosities of LD- and HD-PE, lyocell solutions from two different pulps and nylon 66 resins of different viscosities were measured at different Strain Rates. Graphs of EV versus SR showed a general decline of EV with increasing SR, the higher DP polymers giving higher EV curves.

Processing and properties of melt-spun and drawn 2-methyl-1,3-propanediol substituted poly(ethylene terephthalate) J.E. Spruiell and X. Ling ( University of Tennessee , USA )

Co-polymers of PET have been made with up to 25% of the ethylene glycol being substituted by MPDiol. The 25% level proved unspinnable due to an inability to crystallise, but monofils were obtained from 4, 7, and 10% of the MPDiol. Increasing MPDiol content reduced the crystallinity and molecular orientation obtainable at any given spinning speed and increased the fiber shrinkage. Higher than expected stable spinning speed was a possible advantage of adding up to 7% of the MPDiol, such speeds being necessary to obtain a shrink-free fiber.

The effect of coagulation conditions on the microfibrillar network of a rigid polymer Y. Tsabba, D.M. Rein, Y. Cohen (Technion, Haifa , Israel )

Dry-jet wet spinning of rigid rod polymers yields a microfibrillar structure, the size of the fibrils being important to the fiber's performance in composites. In this work ribbons spun from PBZT (poly(p-phenylene benzobisthiazole)) were coagulated quickly or slowly in water or phosphoric acid before drying with supercritical CO 2 and X-ray diffraction study. Slow coagulation yielded better aligned microfibrils, but of the same size as the fast-coagulated versions. Heat treatment did increase the size of the fibrils in water-coagulated fibers. Dr Tsabba proposed a diffusion controlled nucleation and growth mechanism for fibril formation as being more likely than the currently accepted spinodal decomposition mechanism.

(No print out available)

Melt spinning of fine and ultra-fine PEEK-filaments H. Brunig, R. Beyreuther, R. Vogel, B. Tandler ( Institute of Polymer Research Dresden , Germany )

1 dtex PEEK fibers have been spun to make better yarns when blended with carbon fibers. A questioner commented that with carbon fiber now being cheaper than PEEK, he couldn't see the point.

FIRE RETARDANCY OF FIBERS

Substantive intumescent flame retardants for fibers - Are they feasible? A.R. Horrocks and S. Zhang (Bolton Institute, UK )

Substantive intumescence can be introduced into conventional fibers by reacting them with a char-promoting polyol phosphoryl chloride, providing they have active hydrogen. (e.g. cellulose, wool, nylon). Proban treated cotton appeared to be the most promising substrate, being washable at the boil and surviving as a fibrous char through 600 0 C heating for 10 minutes.

Reaction to fire of ‘M5' rigid rod polymer fibers S. Bourbigot, X. Flambard, M. Ferreira, E. Devaux, F. Poutch (GEMTEX, Roubaix , France )

M5 has a limiting oxygen index of >50%, and compared with Kevlar releases much less heat and smoke when ignited. It's Radiant Heat Release peaks at 50 kW/m 2 compared with 300kW/min for Kevlar. Furthermore while similar to Kevlar in air, it degrades slowly between 450 and 600 0 C under pyrolyitic conditions to form a stable residue with 55% solids (c.f Kevlar which degrades quickly to 40% solids.)

Aramid protective clothing in first choice or recycled - mechanical and thermal behaviour in reaction to fire X. Flambard, S. Bourbigot, M. Ferreira, P.-Y. Quefelec, F. Poutch (GEMTEX, Roubaix , France )

Recycled Kevlar and Twaron show excellent cut resistance but poor abrasion and flame resistance. With the recycled fibers being half the price of the virgin products, and products containing some recycled fiber being hard to distinquish from the 100% virgin products, problems could result.

NATURAL FIBERS

Rheology and lyocell solutions from different cellulose sources B.Collier, J.Collier, S.Petrovan, M.Dever, Z.Li, X.Ling Wei ( University of Tennessee , USA )

14% Solutions of a variety of sources of cellulose had been made in NMMO:
• Unbleached and bleached softwood
• Unbleached and bleached hardwood
• Unbleached and bleached recycled newsprint (pre-consumer)
• Unbleached and bleached thermomechanical pulp
• Unbleached Kudzo pulp
• Unbleached Bagasse pulp
• Dissolving pulps at two DP's
• Cotton linters

Dynamic rheological measurements were performed on an ARES rheometer using parallel plate geometry.

At high deformation rates, lyocell from cotton shows the highest viscosity. Paper pulps were similar to dissolving pulps. The activation energy for the flow of lyocell solutions is slightly higher than for PE or PP melts.

Chemical modification of lignocellulosic fibers A. Gandini (EFPG, St Martin díHeres, France )

Natural fiber composites suffer problems of incompatibility between the fiber surface and the polymer matrix. Chemical modification of the fiber surface could help by:
• Grafting polymers to create non-polar “hairs, umbrellas or bridges” at the fiber surface.
• Using reagents capable of bonding to the cellulosic –OH and polymerising into macromolecules which could co-crystallise with the matrix. (e.g. free radical polymerisation of styrene on the surface of cellulose)
• Using stiff, planar molecules with identical reactive groups on both sides of the plane. (e.g phenylene 1,4 diisocyanate)

Mr Gandini also revealed that his latest studies involved reacting aluminium alkyl with cellulose to allow polyethylene or polypropylene to be polymerised on the surface.

Overview on structural mechanics of natural fibers John Hearle (UMIST, Manchester , UK )

Natural cellulose fibers are composed of crystalline microfibrils generated by the polymerisation of glucose at the surfaces of enzyme complexes. These microfibrils are laid down in helical arrays to form cell walls. In cotton the mechanical properties are dominated by the secondary wall and the small lumen which forms at maturity and collapses on drying.

Protein fibers are more complicated, silk being the simplest and comprising block polymers dry-spun from solution. Wool and hair are the most complex. Here keratin and keratin associated proteins are laid down to form crystalline microfibrils in an amorphous matrix. These are bunched into macrofibrils, assembled into cells (para-, meso-, and ortho-cortex) all within a cuticle of scale shaped cells.

Greater understanding of these structures was becoming more important now that genetic manipulation and computer modelling was possible.

Ultra-high surface fibrous membranes from natural proteins and enzymes Y.-L. Hsieh ( University of California , Davis , USA )

Fibrous membranes were made by electrospinning and stabilised by cross-linking to prevent dissolution in water. These membranes (~0.5 micron fibers) had higher catalytic activity than membranes cast from the same solutions.

The proteins could not be electrospun directly. Blends of casein with polyethylene oxide or polyvinyl acetate had to be used. PEO was best. 80/20 Casein/PEO could be spun as a 10% solution.

Surface analysis of softened paper by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and the Kawabata Evaluation System (KES) M. Parfitt, J.C. Vickerman, C.M. Carr, R. Mitchell, N. Ince, P. Knight (UMIST, Manchester, UK)

The use of KES for bulk softness and ToF-SIMS for surface smoothness allows the factors affecting the perceived softness of toilet tissues treated with different softeners and debonders to be understood.

Conductive polypyrrole coated fibers and yarns A. Kaynak, L. Wang, R. Beltran, X. Wang ( Deakin University , Victoria , Australia )

The effects of monomer, dopant and oxidant concentrations, reaction time and temperature on the conductivity, surface morphology and tensile properties of polypyrrole-coated polyester fabrics were investigated. Optimum oxidant/monomer ratio was found to be 2.22 and the optimum dopant monomer ratio was 0.4. The polypyrrole coat did not affect the tactile properties significantly. The dopant used was anthraquinone-2-sulphonic acid sodium salt monohydrate (AQSA) and the oxidant was ferric chloride hexahydrate. The pyrrole was polymerised onto the fabric over 1-16 hours.

Fiber Assemblies

The effects of mould porosity on fibers distribution in 3D nonwovens R.H. Gong, N. Ravirala (UMIST, Manchester , UK )

Air-laying long fibers straight from a card onto 3D “moulds” gives thin areas where the surface is at an angle to the main direction of air flow. Computational fluid dynamic modelling (CFD) has allowed the porosity of these surfaces to be increased to allow uniform basis weights over the whole surface. The validity of the CFD technique is proved by the near perfect linear relationship between flow rate per unit area of mould and the resulting web thickness.

In private conversation Hugh Gong revealed that he is now working on finger covers for use in hospitals.

The failure behaviour of knitted polyester/urethane acrylate composites: effect of stitch length R. Day (UMIST, Manchester , UK )

A study of stitch length in knitted fabrics used to reinforce a flexible matrix. Longer lengths give weaker composites.

Multiscale modelling of fibrous networks in textile composites P. Potluri, J.W.S. Hearle, T.V. Sagar, P. Mandal (UMIST, Manchester , UK )

Computer modelling of the forces on two filaments twisted together. Once again we seem a long way off getting a useful model of fabric properties.

NANOTECHNOLOGY

Deformation of carbon nanotubes under hydrostatic pressure and in composites R.J. Young , C.A. Cooper, M. Montes, M.P. Halsall, J. Sandler, M.S.P. Shaffer, A.H. Windle (UMIST, Manchester , UK )

Single and multiwall carbon nanotubes (individual molecules with a diameter ~1nm) have been deformed under in a diamond anvil alone and in an epoxy matrix. Raman spectroscopy was used to follow the deformation. Above a critical pressure (~2Gpa) they take on the appearance of graphite, but revert to tubes as the pressure is released. In a polymer matrix, these tubes behave like high modulus carbon fiber. The effective Youngs modulus of the single walled nanotubes dispersed in a composite is estimated at around 1 Tpa (1000 Gpa).

The nanotubes were grown by vapour deposition on dioxide coated silicon containing iron catalyst particles. They grow from the catalyst particles without forming bundles. They can be manipulated with the probe of an atomic force microscope. Raman spectra can be obtained from a single molecule (~10 5 Carbon atoms), and individual molecules have their own unique “breathing mode” vibration. The nanotubes show characteristics of both molecules and fibers.

Keynote: Nanoscience and nanotechnology -The chemistry of the 21st century Sir Harry Kroto ( University of Sussex , Brighton , UK )

This talk by the joint-winner of the 1996 Nobel Prize for Chemistry (for the discoverey of fullerenes – C 60 etc.) was more entertainment than information. He concluded by predicting:

• Nanotube bundles being grown as continuous filaments, their use in composites revolutionising structural materials.
• Extrusion of nanotubes, including boron nitride nanotubes.
• Nanowires, where the carbon tube has insulating atoms on the surface.
• “Carpets” of nanotubes.

Dyeable Polypropylene via Nanotechnology Quingo Fan et al ( University of Massachusetts , Dartmouth ) and Yiqi Yang ( University of Nebraska , Lincoln)

A “PP nanocomposite” is made by dispersing nanoclay in a solution of PP in xylene. The clay (montmorillonite) had been doped with a quaternary ammonium compound to provide dye sites. Acid dyeing occured at the quat and proved stable to washing. Disperse dyeing occured in the “tortuous pathways created by the oriented nanoclay in the polymer system”. The latter gave the best shade depths. 2% and 4% of the clays were added to the PP which was cast into thin film for dyeing.

Asked how the clay content affected the moisture regain or absorbency of the fiber, Mr Fan said these properties had not been measured.

Preparation of nanocomposite fibers for permanent antibacterial effect S.Y. Yeo, H.J. Lee, S H. Jeong ( Hanyang University , Seoul , South Korea )

The use of 11.6nm silver particles in the sheath of a conventional PP bico to make an antimicrobial fiber. Nanointeresting.

FIBERS SURFACES

Effect of surface deposits on softening of fiber surfaces and their relevance to processing Y.K. Kamath, S.B. Ruetsch, E. Petrovichova (TRI/Princeton, USA )

The effects of synthetic finishes on the softness of nylon and polyester fibers was studied using the atomic force microscope in “nanoindentation” mode. Unexpectedly nylon dented less than PET.

Fiber friction measurements increased with time after finish application, the greatest increase being observed with nylon. This measure suggested nylon had a softer surface than PET after exposure to finish.

Surface characterization of fibrous webs using AFM I.A Ansari, T.K. Ghosh ( North Carolina State University , USA )

An attempt to scan the surface of a melt-blown PP fiber using the atomic force microscope raised many problems which prevented detailed information being obtained.

Surface chemical analysis of Tencel treated with a cationic fixing agent S. Rosunee, C.M. Carr, S. Hibbert (UMIST, Manchester , UK )

X-ray photoelectron spectroscopy was used to study the effect of washing on the non-reactive (formaldehyde-free) cationic fixing agents used to improve wash fastness of direct dyes on Tencel. Uncharged nitrogen was seen to be removed from the surface by leaving only the cationic species.

Calvin Woodings

17 th July 2002