Polyurethane elastomer as a matrix material for short carbon fiber reinforced thermoplastic composites

Abstract

Short carbon fibers (CF) with different surface sized (epoxy (EP) and polyurethane (PU)) were used as reinforcing agent in thermoplastic polyurethane (TPU) based composites. Composites containing 5, 10, 15, and 20 weight % sized and desized CFs were prepared by using melt-mixing method. The surface characteristics of CFs were examined by energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR). Tensile testing, shore hardness test, dynamic mechanical analysis (DMA) and melt flow index (MFI) test were performed for determining final composite properties. The dispersion of CFs in TPU matrix was examined by scanning electron microscopy (SEM). Tensile strength, Youngs’ modulus and Shore hardness of TPU were enhanced by the addition of sized CFs. About two-fold improvement for tensile strength and ten-fold improvement for Youngs’ modulus were observed with the incorporation of 20 wt% EP-CF and PU-CF in TPU. The storage modulus of PU-CF containing composites was higher than those of TPU and other composites. No remarkable change was observed in MFI value of TPU after CF loadings. Processing conditions in this work was suitable for composite production. Sized CFs exhibited better dispersion with regard to desized CF due to the stronger adhesion of TPU matrix to fiber surface.