Polymers
with a positive temperature coefficient (PTC) effect have
exhibited poor reproducibility due to the rearrangement of the conductive
network. In order to improve the reproducibility of PTC solely by
regulating the crystalline states for semicrystalline polymers, the
self-nucleation (SN) effect is used to achieve the repeatability of
the skeleton crystal (SC) and driving crystal (DC). The melting of
the DC contributes to the PTC performance, while the presence of the
SC limits the migration of conductive fillers during the melting of
the DC. In this work, a comparative study was conducted first on the
SN process of trans-1,4-polyisoprene (TPI) and TPI/carbon
black (TPI/CB) composites. It was found that the addition of CB narrowed
the melt memory range from 42 to 9 °C, and the overall SN efficiency
was reduced by 40%. Repeatable and appropriate content ratios of the
SC and DC were prepared through step-by-step SN programming, which
improved the reproducibility of PTC effectively.