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Molecular Behavior Studies of Glassy Polymers under Stress.

机译：应力作用下玻璃态聚合物的分子行为研究。

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Molecular bheavior of two structurally different glassy polymers, polystyrene and polycarbonate has been studied under tensile stress, cyclic fatigue and in crazing conditions. This has been accomplished by the use of dynamic fourier transform IR spectroscopy and standard characterization techniques. The study of polystyrene revealed that bulky phenyl side groups on the polymer backbone dictate its mechanical behavior by partially interlocking the chains, causing distortions of phenyl groups and breakage of phenyl interlockings. Further, these interphenyl interferences have been found to depend on processing conditions particularly the orientation conditions. In cyclically fatigued PS films, better packing of polymer chains occurs even though serious molecular level damage occurs in the process. In unoriented films, bulky phenyl side groups highly restrict the chain mobility and therefore stress-relief occurs by crazing of the polymer at the surface. In polycarbonate polymer, the stresses which are distributed are a large number of polymer chains, because of its higher free volume. Fatigued PC films show a shift of alpha and beta relaxation peaks towards lower temperatures indicating an increase in free volume through molecular chain scission. Fatigue-crazing and solvent-crazing in PC occurs via different molecular mechanism, with an extensive damage occurring during the cyclic fatigue.(Author)

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