Percolation-Induced Electrical Conductivity in Bio-Based Shape Memory Polybenzoxazine/Polycaprolactone Composites Reinforced with Carbon Black

Abstract

Bio-based conductive shape memory polymer composites have emerged as promising sustainable multifunctional materials for smart applications. Despite studies on conductive polymer composites and PBZ/PCL systems, limited reports are available on carbon black (CB)-reinforced bio-based polybenzoxazine/polycaprolactone (V-fa/PCL) composites. Therefore, bio-based V-fa/PCL composites containing 90 wt % PCL were reinforced with 0–30 phr CB, and thermal, mechanical, electrical, and shape memory properties were investigated. Thermal analysis showed an increase in the glass transition temperature (Tg) and char yield (4–30%) with increasing CB content, while cross-link density decreased from 53,972 (at 0 phr) to 20,648 mol/m3 (at 5 phr). The highest tensile modulus (360 MPa) was obtained at 10 phr CB. This composition reached the percolation region, exhibiting static-dissipative behaviors with a volume resistivity of 106 Ω·cm. Increasing the CB loading to 30 phr further reduced the volume resistivity to 105 Ω·cm, indicating conductive behaviors. The 10 phr composites exhibited the best shape memory performance, with a shape fixity ratio (Rf) of 89%, a shape recovery ratio (Rr) of 84%, and a recovery time of 160 s. Overall, 10 phr CB was identified as the optimum CB loading, highlighting its potential for antistatic applications, flexible electronics, smart sensing systems, and shape memory structures.