Chlorinated polyethylene (CPE)/carbon black (CB)/ benzoxazine composites with Positive Temperature Coefficient (PTC) characteristics are prepared using the conventional melt-mixing method. The research investigates how benzoxazine content and curing time impact the PTC/NTC characteristics, resistivity, microstructure, and crystallization behavior of these composites.The findings demonstrated a positive correlation between the room temperature resistivity of CPE/CB/benzoxazine composites and benzoxazine content, making the control of benzoxazine content particularly important. Scanning electron microscopy (SEM) reveals that these composites maintain a porous isolated structure regardless of curing time. However, crystallinity decreases as curing time increases. Optimal conditions are achieved with benzoxazine concentration of 2 wt% and a curing time of 45 minutes, resulting in a PTC intensity peak exceeding 5 after R-T cycling. Additionally, at 2 wt% benzoxazine content and a curing time of 60 minutes, a three-dimensional cross-linked network is formed. This network confines carbon black within specific regions, preventing large-scale aggregation and eliminating the NTC effect. After three thermal cycles, the PTC intensity stabilizes around 3.8, indicating good cycling stability.
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