Microdiamond/PLA composites with enhanced thermal conductivity through improving filler/matrix interface compatibility

Abstract

Polylactic acid (PLA)-based composites filled with 20 or 50μm-diameter microdiamond are synthesized by hot pressing. Through improving the interface compatibility between the filler and the matrix enabled by octadecylamine (ODA) coating on the microdiamond particles, the maximum thermal conductivity of the composites is 2.22Wm−1K−1, which is a ~10-fold increase in comparison with that of pure PLA. According to the analysis on the glass transmission of the composites and the surface chemistry of the fillers using DSC, FI-IR, and Raman microscopy, it is found out that ODA is connected with the OH group on the microdiamond surface through hydrogen bonding and an interfacial structure of PLA/ODA/microdiamond is formed. Thus, the interfacial thermal transport between PLA and microdiamond is significantly improved, leading to the enhancement of the thermal conductivity of the composites. Our work presents a simple method to modify the surface chemistry of microdiamond and to improve the interface compatibility between microdiamond and PLA. The microdiamond/PLA composites with large thermal conductivity are promising thermal management materials used for modern electronic products.