Physico-mechanical characterization and thermal property evaluation of polyester composites filled with walnut shell powder

This paper reports on the processing and overall characterization of walnut shell powder (WSP) filled polyester composite. The effects of this filler on the properties of polyester resin are studied by conducting various characterization tests under controlled laboratory conditions. The composite formation mechanism has been explained by the interpretation of Fourier transform infrared (FTIR) spectroscopic and X-ray Diffraction (XRD) analysis. The study reveals that the incorporation of WSP particles modifies the density and porosity of the composites along with their tensile, compressive, flexural, and impact strengths. Thermo-gravimetric analysis (TGA) is done on the samples to get an insight into their thermal stability. Measurement of thermal conductivity is carried out on samples of different compositions, and it is found that the inclusion of walnut shell powder leads to significant improvement in the thermal insulation capability of polyester resin. It is recorded that with an increase in the WSP content from 0 to 20 wt. % in polyester, the value of the effective thermal conductivity (K-eff) drops by about 42%. It is further seen that with the incorporation of WSP, the coefficient of thermal expansion (CTE) of polyester is substantially lowered.