Polyethylene, disposable diapers

Lower-density E-plastomers have found alternate use in cast film processes to make elastic film laminates with good breathability which contain laminates of liquid impermeable extensible polymeric films with extensible-thermoplastic-polymer-fiber nonwovens and nonwoven webs of polyethylene-elastomer fibers as the intermediate layers. The development relates to a breathable film including an E-plastomer and filler that contributes to pore formation after fabrication and distension of the film. The method and extent of distension is designed to produce a breathable film by stretching the film to form micropores by separation of the film of the E-plastomer from the particulate solids. This film is useful for manufacture of absorbent personal-care articles, such as disposable diapers and sanitary napkins and medical garments. In detail, these constructions comprise a liquid impermeable extensible film comprising polyolefins. The outer layer contains extensible-thermoplastic-polymer-fiber nonwovens, and an elastic intermediate layer contains nonwoven webs of fiber E-plastomers. The intermediate layer is bonded to the film layer and the outer... 

Polypropylene (PP) is used in a variety of areas, from snack food packaging to battery cases to disposable diaper linings. It is frequently interchanged for polyethylene or polystyrene. 

The disposable diaper of today is composed of an inner layer of polyester that allows liquids to pass through to a layer of absorbent material, and an outer waterproof plastic layer of polyethylene film. The design was developed by many researchers through trial and error. 

Disposables are also considered to be an environmental threat. Only some of the materials used in the diapers are biodegradable (the wood pulp and SAP). The polyethylene and polyester sheets are not biodegradable neither is the elastic used for better fit, nor the polypropylene used for the tape that is employed as a fastener. Disposable diapers account for up to 2 percent of the total volume of landfills in the United States. The lifetime of the diaper in the landfill depends on several environmental factors soil condition, groundwater flow, and the presence of other materials in the soil. see also Matertals Science Polymers, Synthetic. 

Consider the disposable diaper. The outer, waterproof layer is composed of polyethylene. The polymeri2ation reaction that produces polyethylene is shown in Section 12.4. The diapers have elastic to prevent leaking. The elastic is made of a natural polymer, rubber. The monomer from which natural rubber is formed is 2-methyl-l,3-butadiene. The common name of this monomer is isoprene. As we will see in coming chapters, iso-prene is an important monomer in the synthesis of many natural polymers. 

Nonwoven products are usually constructed of polyethylene and polypropylene materials which are very hard to adhere to. In spite of this, hot melt adhesives are used almost exclusively to bond most structures. Diapers represent the largest product line using hot melt adhesives. In the fiiture it may be that incontinent diapers and absorbent pads will be an even larger market. EVA-based hot melts are believed to hold about 60% of the market, with low molecular weight polyethylene and atactic polypropylene making up the remainder. The type of adhesive used is constantly under change as the performance requirements change. The disposable diaper has penetrated approximately 80% of the total diaper market. 

A very large tape market of many millions of square yards is for diapers. The common disposable diaper is secured with tapes mounted on attached release liners which adhere to the diaper s polyethylene backing. 

Functional derivatives of polyethylene, particularly poly(vinyl alcohol) and poly(acryLic acid) and derivatives, have received attention because of their water-solubility and disposal iato the aqueous environment. Poly(vinyl alcohol) is used ia a wide variety of appHcations, including textiles, paper, plastic films, etc, and poly(acryLic acid) is widely used ia detergents as a builder, a super-absorbent for diapers and feminine hygiene products, for water treatment, ia thickeners, as pigment dispersant, etc (see Vinyl polymers, vinyl alcohol polymers). 

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