Optimization strategy for thermal-mechanical performance balance of polyethylene composites under synergistic effect of hybrid fillers

Purpose: This study aimed to develop an optimization strategy for balancing thermal and mechanical properties in polyethylene composites using hybrid AlN/BN fillers. Methods: High-density polyethylene composites were prepared with varying ratios of surface-modified spherical AlN and platelet h-BN (20-40 wt%) via melt blending and compression molding. Response surface methodology with central composite design (13 runs) was employed to optimize filler compositions. Thermal conductivity, tensile properties, and crystallization behavior were evaluated according to ISO 22007-2, ASTM D638 standards, and DSC analysis. Findings: The optimal formulation (15 wt% AlN + 15 wt% BN) achieved a comprehensive performance index of 0.82, with thermal conductivity of 1.45 W/m·K (260 % enhancement) and tensile strength of 31 MPa (89 % retention). DSC analysis revealed controlled crystallinity reduction from 66.5 % to 58.0 %, facilitating phonon transport through enhanced fillermatrix interfaces. The synergistic effect was attributed to a bimodal packing structure (density 0.68) created by morphological complementarity between spherical AlN and platelet h-BN, establishing dual thermal pathways. Practical implications: The developed composites demonstrate potential for thermal management applications in power electronics and LED packaging, where balanced thermal-mechanical performance is critical. The identified processing window (12-18 wt% for both fillers) ensures robust industrial scalability with conventional melt processing techniques.