Elastomers blowing agents

The compositions consist of a heat-plastified mixture of an ethylene homopolymer or copolymer, about 3 to 30 pbw of an elastomer, a stability control agent, which is a partial ester of a long chain fatty acid with a polyol, higher allyl amine, fatty acid amide or olefinically unsaturated carboxylic acid copolymer, and a hydrocarbon blowing agent having from 1 to 6 carbon atoms and a boiling point between -175 and 50C. 

Polyurethane rubber (PUR). Not only in the thermosets (and the thermoplastics), but also in the field of synthetic elastomers polyurethanes have found a position, namely as a softer type. It is, again, formed from two components and is, with a blowing agent, processed into a foam. Polyether mattresses belong to this category, but also microcellular structural foams, used in bumpers, head- and arm-rests in motorcars, etc. 

The specialists in rubber additives are distinctly different from the specialists in additives for plastics, even though the same products are sometimes used in both industries blowing agents (azodicarboamide), phenol antioxidants (BHT, 2246), phosphites (tris-nonylphenyl phosphite). In the first place, additives for elastomers, unlike those which might come into contact with foodstuffs, do not require official approval, which... 

The production of polyurethane involves the controlled polymerization of an isocyanate, a long-chain-backbone polyol and a shorter-chain extender or cross-linker. The reaction rates can be controlled through the use of specific catalyst compounds, well known in the industry, to provide sufficient time to pour or otherwise transfer the mix and to cure the polymer sufficiently to allow handling of the freshly demolded part. The use of blowing agents allows the formation of a definite cellular core (thus the term microcellular elastomer ) as well as a non-porous skin, producing an integral sandwich-type cross section. 

The blowing agent for microcellular elastomers is water. The amount of water should be accurate, and its accuracy can be obtained by a water-containing solution, such as liquid sodium sulfonate of vegetable oils containing a small amount of water. The catalysts to be used are those used in urethane foams, e.g., tertiary amines, and tin catalysts. The above ingredients are mixed and poured into a hot mold and cured in a defined period of time. After demolding, a post cure is applied to complete the polymer-formation reactions. 

Nitropore . [Uniroyal] 4,4 -Oxybis (bCTzenesulfcmhydrazide) nioogen-re-leasing blowing agent for elastomers, thermoplastics, rubbernresin blends. 

USE Blowing agent for elastomers and plastics. Initiator for free radical reactions Griesbaum el aL. J. Org Chem. 3D, 261 (1965). 

Phenyl tetrazole 5-Phenyl-2H-tetrazole Tetrazole, 5-phenyl- 1H-Tetrazole, 5phenyl- 2H-Tetrazole, 5-phenyl-. Blowing agent for foaming plastics and elastomers at elevated temperatures. Degussa-HOIs Corp. 

The most important use of phosgene is in the preparation of diisocyanates from the corresponding amines. These compounds have reached major importance as blowing agents for elastic and rigid polymeric foams and as cross-linking agents in improved elastomers and polymers. 

In the absence of a blowing agent and with conditions favoring the formation of linear chains, thermoplastic polyurethane elastomers can be formed. Materials with different properties can be obtained by altering the ratio of hard to soft blocks, and it is also observed that, in many cases, the hard segments can crystallize. This can give rise to phase-separated structures, shown schematieally in Figure 2.6, which behave as thermoplastic elastomers (see also Section 15.6). 

Uses Blowing agent in printing inks, PU, PVC plastisols, fabrics, paper expanded microspheres as ultra-low density tillers tor use in engineered prods, in which other fillers would not be suitable, e.g., syn. marble and wood, coatings, sealants, explosives, auto, marine fillers, molding compds., composites, paint and crack fillers, cable fillings, elastomers Features Unexpanded microspheres Expancel 551 DE 20 [Expancel]... 

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