ANALYSIS OF POSITIVE TEMPERATURE COEFFICIENT EFFECT IN CARBONNANOFIBER AND CARBON BLACK FILLED SHAPE MEMORY POLYURETHANE COMPOSITES

摘要

The objective of this work was to determine the temperature dependent resistivity and positive temperature coefficient (PTC) behaviors of shape memory polyurethane (SMPU) composites. SMPU composites were synthesized from diphenylmethane diisocyanate, 1,4-butanediol, and polycaprolactonediol, and carbon nanofiber and carbon black as fillers. Our results showed that SMPU composites exhibit pronounced PTC effects. Filler loading, crystallinity of the matrix, filler-matrix interactions, and temperature, all influenced PTC effects. It was also observed that the non-linear thermal expansion and PTC effect in composites have close relationship.