Effects of oxidized/treated non-metallic fillers obtained from waste printed circuit boards on mechanical properties and shrinkage of unsaturated polyester-based composites

Abstract

The investigation of the influence of acid/base treatment and addition level of non-metallic fractions (NMFs), obtained by processing of printed circuit boards, on the mechanical properties and shrinkage of unsaturated polyester resin (UPR)-based composites was main topic presented in this paper. NMF particles were treated using four different oxidative/etching agents: H2SO4/KMnO4 (NMF1), H2SO4/HNO3 (NMF2), HNO3 (NMF3), and NaOH (NMF4). Treated NMF(1-4) particles were characterized using fourier transform infrared, Boehm titration, optical microscopy and SEM analysis. Tensile strength and micro Vickers hardness of UPR/NMF(1-4) composites were the most improved with addition of 0.5wt% of filler, for 5.9-24.7%, in comparison to composite filled with non-treated NMF particles. Cross-linking density (nu), storage, and loss modulus (G' and G''), damping factor (tan delta) and glass transition temperature (T-g) of the composites were determined from the dynamic-mechanical analysis (DMA) testing. Shrinkage measurements, performed using Aramis 6.2.0, showed significant improvement in shrinkage reducing, for 17.8-30.6%, by introduction the oxidized NMF particles. Qualitative/quantitative evaluation of NMF(1-4) surface functionalities helped in understanding their influences on mechanical, DMA and shrinkage properties change of studied composites. POLYM. COMPOS., 40:1170-1186, 2019.