The Crystallization Behavior of poly(3-Hydroxybutyrate-Co-3-Hydroxyhexanoate) with Different Nucleating Agents

This study investigates the impact of various nucleating agents on the crystallization be-havior, thermal stability, and mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HBHHx) having 6 wt% of 3HHx units, which is a biodegradable polymer with inherently slow crystallization kinetics. Bo-ron nitride (BN), poly(3-hydroxybutyrate) (PHB), talc, and others were incorporated to en-hance crystallization. Differential scanning calorimetry (DSC) showed that BN and PHB significantly increased the crystallization temperature and reduced crystallization half-times, with BN exhibiting the highest efficiency. Lauritzen–Hoffman analysis con-firmed lower nucleation barriers for nucleated samples. Polarized optical microscopy (POM) revealed that nucleating agents altered spherulite morphology and increased growth rates. Under fast cooling, only BN induced crystallization, confirming its superior nucleation activity. Thermogravimetric analysis (TGA) indicated minimal changes in thermal stability, while mechanical testing showed a slight reduction in stiffness without compromising tensile strength. Overall, BN emerged as the most effective nucleating agent for enhancing P3HBHHx crystallization kinetics, providing a promising strategy for im-proving processing efficiency and reducing cycle times in industrial applications.