Sunday 2 February 2014

Hydroentangled Air-laid flax Nonwovens

More from the EDANA NIA 2013 Conference in Roubaix...

Philippe Mesnage of ITFH (France) is evaluating hydroentanglement as an alternative to needlepunching for making flax nonwovens for composite reinforcement. The raw flax contains ~70-75% cellulose with 10-15% of hemicellulose, 3-5% lignin and a similar proportion of pectins. Mechanically refined flax (MRF) tows were cut into lengths of 25-35mm for airlaying and compared with a more fully refined 45mm flax intended for spinning into yarns (SF). MRF was coarse – 34 to 90 on the IFS scale (Flax Standard Index) compared with 20-30 IFS for the SF fibres. These long fibres clogged the air-lay drums and further work was carried out with fibres chopped to 15mm which could be successfully laid into ~150gms sheets.

After hydroentanglement, nonwoven tensile strengths were highest for the SF fibres (358N/5cm) compared with 215N/5cm for the best of the MRF.  Tear strengths were however comparable, presumably due to the higher denier of the MRF.  The extra stiffness of the MRF samples was not just down to the coarser fibres.  Mr Mesnage thought the non-cellulose components of the fibre were being solubilised in hydroentanglement and acting as a chemical binder.  Asked what advantages this route might have over the needlepunched route he thought there was a potential for higher productivity from the faster laying and bonding machinery and added that the end product was completely natural, made in the EU and used no added binders.

No comments: