A Comprehensive Study on The Accelerated Weathering Properties of Polypropylene—Wood Composites with Non-Metallic Materials of Waste-Printed Circuit Board Powders

Abstract

In this study, non-metallic materials of waste-printed circuit board powders (WPCBP) were successfully used as reinforcing filler to produce polypropylene (PP)–wood composites, and their effect on the weathering properties of PP composites were fully evaluated via oxidation induction time (OIT), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry, vicat softening point (VST), scanning electron microscopy, and mechanical properties analysis. The OIT analysis confirmed that the anti-thermal oxidative aging properties of PP–wood composites were decreased with the loading of WPCBP. Apart from that, the PP composite, reinforced with 30 wt.% of WPCBP, exhibited the highest value of active energy, which suggests that it is more sensitive to temperature and oxygen when compared with other PP composites. The mechanical properties analysis revealed that neat PP exhibited the poorest weathering properties after being subjected to UV exposure, and its retention rate of tensile strength and notched impact strength were only 70.6% and 59.6%, respectively, while WPCBP and wood flour (WF) could efficiently improve the retention rates of the mechanical properties of the PP composites when subjected to UV exposure. The visual appearance of the PP composites after being subjected to UV exposure showed more and smaller cracks with the loading of WPCBP and WF. The ATR-FTIR results revealed that the carbonyl index increased for all the weathered samples, and the more WPCBP was added into the PP composites led to a higher carbonyl index value, which might be due to the multivalent transition metals in WPCBP, which accelerate the photo-oxidation of the PP composites. The VST results show that both WPCBP and WF can effectively enhance the heat deformation resistance of the PP composites that have been subjected to UV exposure.