Contributions of TCA-KTTO-modified quartz tailings and CPE toughener in PVC composites to enhance the mechanical-thermal performance

Abstract

Large volumes of quartz tailings (QT) are currently stockpiled, which are difficult to treat effectively. Utilizing QT as a filler for high-demand polymeric materials is an effective strategy for large-scale and high-value utilization of solid waste. It is consistent with the goal of sustainable development. The mechanical performance and thermal stability of commercially available polyvinyl chloride (PVC)–based composites are limited due to the agglomeration of inorganic filler and low inorganic–organic interfacial compatibility. mQT/PVC and chlorinated polyethylene (CPE)–mQT/PVC composites were fabricated via dry modification, CPE toughening treatment, and open refining hot-pressing. The coupling agent molecules were grafted onto the mQT surface via Si-O-Ti bonding. mQT was uniformly dispersed and tightly adhered in the PVC matrix, particularly at a titanate coupling agent dosage of 2.0 wt%. The density, surface hardness, Young’s modulus, flexural modulus, and thermal conductivity of 50 wt%-mQT/PVC increased by 28.50%, 19.64%, 247.94%, 88.61%, and 153.11%, respectively, compared with those of pure PVC. T40 wt% for 50 wt%-mQT/PVC reached 487.39 °C. After toughening treatment, the impact strength of 15.0 phr-CPE-mQT/PVC increased by 47.38% compared to that of mQT/PVC. Pilot scale test results show that mQT/PVC and CPE-mQT/PVC composite plates, and CPE-QT/CaCO3/PVC co-extruded hollow floors met the Chinese standard GB/T 24508–2020. The mQT/PVC and CPE-mQT/PVC composites had excellent mechanical properties and high thermal stability, thermal conductivity, and glass transition temperature. This study provides an economical QT/PVC composite and proposes a sustainable strategy for the resource utilization of solid waste.