Improvement of thermo-mechanical and dielectric properties of poly(lactic acid) and thermoplastic polyurethane blend composites using a graphene and BaTiO3 filler

This study focuses on the development of composite materials using thermoplastic polyurethane (TPU) and poly(lactic acid) (PLA) with fillers such as barium titanate (BaTiO3) and graphene. Suitable surface treatment of filler particles is applied to activate the fillers to enhance the compatibility between the fillers and polymer matrix. Specifically, the BaTiO3 particles are hydroxylated and treated with glycidyl methacrylate (GMA), which acts as a compatibilizer between the two matrix polymers. On the other hand, the graphene particles are hydroxylated and treated with isophorone diisocyanate (IPDI), which reacts with the TPU soft segment chains during composite fabrication. The composite samples are fabricated via melt-blending at 190degree celsius, followed by mini molding at the same operating temperature for subsequent analysis. The results demonstrate a three-fold improvement in the dielectric constant of 40 wt.% BaTiO3 and graphene-TPU-PLA blends composites relative to that of the neat TPU, along with an improved tensile strength. The tensile strength improvement is attributed to the support of the TPU matrix against the low ductility of the PLA. The thermal conductivity was doubled as compared with the neat TPU-PLA matrix for the 40 wt.% BaTiO3 and graphene-TPU-PLA blends.