Sunday, 18 November 2012

Practical Polysaccharides (Part 5) A solution to the ammonia odour problem in personal absorbents

Part 5 of the paper by Jacek K. Dutkiewicz of Buckeye Technologies Inc given at this years Insight Conference organised by MTS in Norfolk Virginia. (Click here for Part 1)

An example of using cellulose fibers both for this purpose and simultaneously, for absorbency was presented a few years ago at the Insight Conference [5].   The concept of storing a urease inhibitor in absorbent fluff proved to be very effective for eliminating ammonia odor which normally occurs due to enzymatic hydrolysis of urea.   This solution to the odor problem is shown in Fig. 8. 

 Inhibition of microbial ammonia production had an additional benefit for skin wellness, which is maintaining the pH at a level slightly below neutral.

Absorbent products are composed of various components serving different performance functions. Quite often this creates a necessity for trade-offs and compromises, for example between maximizing the capacity of a superabsorbent polymer (SAP) and minimizing the blockage of pores within the fiber matrix.  Closing of the pores through which fluid flows may be caused by diffusion of uncross-linked, soluble fractions from the polymer. They increase the viscosity of the liquid and thus lower its rate constant. The blockage of capillaries between the fibers can be caused also simply by rapid swelling of the SAP powder which closes the conduits through which the liquid could otherwise move easily.  

Known solutions to the pore blockage problem involve increasing cross-link density in the whole mass of the superabsorbent polymer or creating a highly cross-linked skin on SAP particles.  Either way, the overall absorbent capacity of the material becomes then compromised.  The earlier mentioned TRIZ innovation theory calls this kind of situation an “engineering contradiction.”  Rather than looking for a compromise, TRIZ gives guidance how to separate the two opposite functions and use two components instead of one material, each component functioning independently in the system.  The following examples are some existing but perhaps already forgotten solutions to the described problem.  Again the ability of cellulosic fibers to store suitable functional agents will be the key tool in this case.

(Go to Part 6)

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