Elastomers, structure characterization chemical composition

The formulations used in the manufacture of polyurethane elastomers are critical, as variations in the chemical composition of raw materials seriously affect properties. In particular, trace impurities can catalyze or inhibit the various reactions, changing network structures and hence final elastomer properties. For these reasons analytical tests to quantify the quality and reactivity of urethane intermediates have been developed and their use in urethane technology is essential. Additionally, characterization and identification of unknown polymers is frequently necessary. Finally, it is necessary to have procedures which characterize the structure and degree of crosslinking (where this applies) of polyurethane elastomers. 

The most typical adhesive solvents are those based on elastomers, compounds characterized by the fact that they have a strong natural adhesiveness, especially in respect of themselves (the phenomenon of self-adhesion, the instantaneous adhesion of two films of glue after almost total evaporation of the solvent, is the basis for the composition of the contact glues especially neoprene-based (Fletcher 1971)). The basic chemical composition of neoprene synthetic rubber is polychloroprene (O Fig. 14.6). The polymer structure can be modified by copolymerizing chloroprene with, for example, 2,3-dichloro-1,3-butadiene to yield a family of materials with a broad range of chemical and physical properties. 

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