Effects of inorganic‐organic surface modification on the mechanical and thermal properties of poly(vinyl chloride) composites reinforced with fly‐ash

Abstract Fly ash (FA) derived from the combustion of coal is considered a potential reinforcing filler for polymers, but its application is somewhat limited by the number of hydroxyl groups on the surface. In this study, FA was modified with sodium hydroxide (NaOH) (denoted as OH‐FA), resulting in an increase in the number of OH groups on the surface of FA and thus improvement of the interfacial adhesion between FA and polyvinyl chloride (PVC). OH‐FA was subjected to ball milling to induce mechanochemical activation aided by a new polyether titanate coupling agent (ETi 4 ) (denoted as M‐ETi 4 ‐OH‐FA). The results show that the functional groups of ETi 4 can interact with the OH groups on the surface of FA via electrostatic interactions, chemical interactions, intra‐ and intermolecular hydrogen bonds by ball milling, which can increase the compatibility and interfacial bonding between FA and PVC, and improve the mechanical and thermal characteristics of PVC composites. Significantly, the impact strength and yield strength of M‐ETi 4 ‐OH‐FA/PVC composite reaches 6.2 kJ/m 2 and 64.9 MPa, which is increased by 86.8% and 13.6% compared with that of PVC, and by 18.2% and 14.6% compared with that of ETi 4 ‐OH‐FA/PVC, respectively. The thermal stability is also higher than that of other PVC composites, and the rapidest degradation temperature reaches 297°C, which is 16°C higher than that of pure PVC.