Thermal degradation of polyurethanes. Part VI. Influence of segment structure of polyurethanes on their thermal stability
Kinetics of thermal degradation of segmental polyurethanes (PU) differing in the soft-to-hard segmentratio have been investigated. PU were obtained from the mixtures of poly(ethylene adipate), 4,4'-diphenylmethanediisocyanate and 4,4'-dihydroxydiphenylmethane of different compositions. PU were degraded by heating in isothermal and dynamic conditions. Several steps of degradation of different rate have been observed. The initial rate of degradation increases with the increase of hard-segment content and it determines the course of-degradation. The urethane group is stabilized by soft segments due to hydrogen bonds between NH group and C=0 group from soft-segment esters.
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