Effect of boron nitride on the pyroresistive properties of smart conductive polymer composites: eliminating the negative temperature coefficient effect

Self-regulating heating nanocomposites featuring a positive temperature coefficient (PTC) effect offer significant advantages in resistive heating applications due to their intrinsic temperature-controlling ability without external intervention. However, the subsequent negative temperature coefficient (NTC) effect, leading to potential electrical shorting, remains a major challenge. This study explores the impact of a secondary nanofiller, which is electrically insulating yet thermally conductive, in mitigating the NTC effect in smart conductive nanocomposites (CPCs). Through a systematic analysis of morphological changes and filler network formation, we reveal how boron nitride, as a secondary nanofiller, mitigates the NTC effect by reducing electrical contact points between graphene nanoplatelets and increasing viscosity to prevent filler re-agglomeration. The volume ratio between polymer matrix and conductive filler has been identified as a key factor in eliminating the NTC effect in CPCs with 2D fillers. This study provides deep insights into the underlying mechanisms of NTC effect in conductive polymer nanocomposites, with feasible strategies for enhancing the safety and reliability of self-regulating heating composites. An effective approach to eliminate the undesirable NTC effect with a secondary nanofiller to reduce the electrical contact points.