Foam rubber, polyurethane

Aniline, which is used not only to synthesise drugs, pesticides and explosives but also as a building block for materials such as polyurethane foams, rubber, azo dyes, photographic chemicals and varnishes, is manufactured at a quantity of approximately three million tons each year [61]. The toxic effects of aniline include increased nitration of proteins in the spleen [62]. 

In medicinal applications, the hydroxyl group irritates the stomach lining. Chemically, the hydroxyl group can react to form urethanes or esters, and hence form a polymer network. Polyurethane foam rubber frequently contains large amoimts of reacted castor oil, for example. The glass transition of castor oil polyesters are of the order of —50°C (80). 

The low hardness has led to uses in printers rollers and stereos. It is, however, to be noted that when the material has been used to replace cellular rubbers or flexible polyurethane foams in sealing applications, problems have arisen where it has not been appreciated that although the rubber is very soft it is for practical purposes incompressible. 

Whereas the solid polyurethane rubbers are speciality products, polyurethane foams are widely used and well-known materials. 

Various elastic elements are added to disposable sanitary products. Strands of lycra, natural rubber, polyurethane foam, and other elastic laminates are applied to provide good fit and avoid leakage. These are attached with adhesives. While non-PSA formulas such as polybutene-based [64] and polyamide [65] adhesives have shown utility, as well as benefits in terms of resistance to baby oils and lotions, adhesives based on styrenic block copolymers still dominate. SBC-based... 

The main uses of toluene are as a solvent in paints, rubber, and plastic cements and as a feedstock in the manufacture of organic chemicals, explosives, detergents, and polyurethane foams. Xylenes (which exist as three isomers) are used in the manufacture of DMT, alkyd resins, and plasticizers. Naphthalene is mainly used in the manufacture of dyes, pharmaceuticals, insect repellents, and phthalic anhydride (used in the manufacture of alkyd resins, plasticizers, and polyester). 

Virtually all of the nitrobenzene made is converted to aniline. The most important use of aniline is for the preparation of 4,4 -diaminodiphenyl methane (commonly called methylenedianiline or MDA), an intermediate to one of the main ingredients used to make polyurethane foams and rubber. Aniline is also used to make other rubber chemicals, textile fiber intermediates, dyes, and pharmaceuticals. 

Polyurethane foams are lighter than foam rubber and have displaced many of its applications, such as in bedding, cushions, car seats, armrests, and crash pads. Laminates are used widely in clothing as padding. 

Uses Intermediate for pharmaceuticals, dyestuffs, emulsifying agents, and rubber accelerators solvent for dyes, resins, and oils catalyst for making polyurethane foams. 

Atomic force microscopy and attenuated total reflection infrared spectroscopy were used to study the changes occurring in the micromorphology of a single strut of flexible polyurethane foam. A mathematical model of the deformation and orientation in the rubbery phase, but which takes account of the harder domains, is presented which may be successfully used to predict the shapes of the stress-strain curves for solid polyurethane elastomers with different hard phase contents. It may also be used for low density polyethylene at different temperatures. Yield and rubber crosslink density are given as explanations of departure from ideal elastic behaviour. 17 refs. 

While unaffected by water, styrofoam is dissolved by many organic solvents and is unsuitable for high-temperature applications because its heat-distortion temperature is around 77°C. Molded styrofoam objects are produced commercially from expandable polystyrene beads, but this process does not appear attractive for laboratory applications because polyurethane foams are much easier to foam in place. However, extruded polystyrene foam is available in slabs and boards which may be sawed, carved, or sanded into desired shapes and may be cemented. It is generally undesirable to join expanded polystyrene parts with cements that contain solvents which will dissolve the plastic and thus cause collapse of the cellular structure. This excludes from use a large number of cements which contain volatile aromatic hydrocarbons, ketones, or esters. Some suitable cements are room-temperature-vulcanizing silicone rubber (see below) and solvent-free epoxy cements. When a strong bond is not necessary, polyvinyl-acetate emulsion (Elmer s Glue-All) will work. 

As for the mattress core, natural latex is the environmentally preferred stuffing, a rubber-tree product that can be sustainably sourced. Some mattresses are stuffed with a mix of natural and synthetic latex, as the latter substance is cheaper (although chemicals are added in the manufacturing process). Both choices are better than the polyurethane foam found in most conventional mattresses. Still other mattress cores have an innerspring system and batting, often cotton. In-nerspring mattresses are a popular crib choice some people think their firmness prevents SIDS. 

Foams can be made from thermoplastics, thermosets and rubbers. Densities can be obtained from nearly solid down to 200 times diluted. Structural (or integral) foams have a solid skin. The best known foam materials are polystyrene foam, polyurethane foam and polyether foam. 

TG-MS is an ideal technique for identifying residual volatiles in polymers. The detection of residual volatiles (and of other impurities) can often yield clues as to manufacturing processes. In many cases, such as in the determination of highly volatile materials, of residual solvents or plasticisers, use of TG-MS is requested. Specifically, there are reports on the entrapment of curing volatiles in bismaleimide laminates [145] and elastomers [48], on the detection of a curing agent (dicumylperoxide) in EPDM rubbers and of bromine flame retardants in electronic waste [50], of plasticisers such as bambuterol hydrochloride [142] or TPP and diethylterephthalate in cellulose acetate [143], on solvent extraction and formaldehyde loss in phenolic resins [164], and on the evolution of toxic compounds from PVC and polyurethane foams [146]. 

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