Achieving High Thermal Conductivity, Good Electrical Insulation, and Balanced Mechanical Properties in Biodegradable Polymer Composites with Low Filler Content

Biodegradable polymer composites usually require high filler loadings to increase their thermal conductivity, which can, in turn, compromise their mechanical and electrical insulation properties. In this study, we successfully developed biodegradable poly(butylene succinate) (PBS)-based composites with an oriented segregated double-filler network. The construction of this network involved melt blending PBS and carbon nanotubes (CNTs), followed by crushing to obtain the masterbatch (PBS/CNTs). Subsequently, boron nitride (BN) powder was mechanically mixed with the PBS/CNTs masterbatch, and the hot-pressed PBS/CNTs@BN sheets were subjected to forced uniaxial orientation manipulation. The resultant composites exhibited significantly in-plane thermal conductivity, reaching 1.0 W m –1 K –1 at 3 vol % CNTs and 5 vol % BN content and even reaching up to 2.2 W m –1 K –1 at 3 vol % CNTs and 20 vol % BN content, which is nearly 10-fold higher than that of pure PBS. Furthermore, composites containing 3 vol % CNTs and 5 vol % BN fillers exhibit good electrical insulation characteristics (5 × 10 –10 S/cm) and maintained balanced mechanical properties (tensile strength of 37.7 MPa, impact toughness of 10.0 kJ/m 2 ). Overall, the oriented segregated double-filler networks effectively endowed the biodegradable polymer composites with good thermal conductivity, electrical insulation, and acceptable mechanical properties at low filler concentrations. As a result, these multifunctional biodegradable polymer composites hold great promise for the thermal management of electronic devices.