Diapers and Polymers Joseph Clearyl Notre Dame College of Ohio, 4545 College Rd., Cleveland, OH 44121 Consider a simple product. Consider an article of clothing that almost all have worn daily during a portion of their lives-a product considered an "essential" piece of wear. Consider the evolution of this product based on its use and the properties needed for it to stand u p against daily abuse. This article attempts to illustrate how several polymers have been incorporated into the design of this product in order to take advantage of their various properties. No one of them has all the needed properties; but several, used together, provide a combination of materials with properties that provide a much needed product-the disposable diaper. The oroduct-the babv. dianer. . Orieinallv a oiece of simple cotton cloth or other absorbent &teri& ;inned a t the sides. Later in its evolution the cotton material was covered with a waterproof liner, providing some additional measure of orotection. But it leaked. The waternroof liner snlit when washed repeatedly, and i t did not easil; conform tithe body without bunching or bulking. Now let us consider the problems associated with developing a diaper based on polymers, a disposable diaper. Firsthand obkrvation of subiicts who use this nroduct reveals fairly stringent r e q u i r e k n t s for its materiais. The product is subiected to considerable abuse in various wavs. This create: a need for several different properties. ~ b e b r o d u c t is subject to stretching, pulling, pokes, and tears. Compression and shear forces act on it. It is subject t o intermittent loadine witb aaueous solutions of acids. bases. and oreanics. I t must withstand solid loads. Its materials must meet high standards of nontoxicity, both dermal and oral (some babies like to bite into their prizedpossession). The adhesives holding i t in place should be pre-applied, and stick to some materials (i.e., the diaper) without sticking to others (the body, clothes, and the wall). The materialssbould be durable enoueh to he reused or cheav enoueh to he discarded after one ise. The materials shduld be-flexible, but not limp, withstand water in certain parts but absorb i t in others. And the diaper should he manageable witb one hand. Trying to hold a sauirmer with one hand while ooenine. formine. and closing 8 diaper with the other makes one sppreciaG the strides in the development of the disposable diaper made possible with polymers. Let's consider some of the properties of one major brand of disposables, " L u v ~ " ~and , the polymers that are used to provide the property requirements cited above. Some of the properties are essential, while others are merely desirable from a consumer's view. Figure 1 and 2 show a simplified cross section and top view of a disposable diaper.
absorbent material should retain moisture of many times its weight without releasing appreciable amounts and without excessive vackine. For theGeauirements the nolvmer used for its absorbent properties is one of nature's original polymers-cellulose. Two sources of cellulose are cotton and wood pulp. Formerly, diapers were made of cotton, but today the cellulose in disposables is refined wood nulo. This cellulose still meets absorbency needs along witb being relatively inexpensive and easy to process. As can be seen the cellulose
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OH cellulose po~y-8-(1-4)-~-glueose
