Comparison between polyether titanate and commercial coupling agents on the properties of calcium sulfate whisker/poly(vinyl chloride) composites

In this study, calcium sulfate whisker (CSW) was modified with a newly synthesized polyether titanate coupling agent (eTi4000) and four commercial coupling agents, including two silane coupling agents (KH560 and KH570) and two titanate coupling agents (KR38S and KR138S), respectively, and then the modified calcium whisker (mCSW) was incorporated into poly(vinyl chloride) (PVC) by melt blending to prepare mCSW/PVC composites. The morphologies, mechanical properties and thermal stability of these mCSW/PVC composites were compared. The results reveal that the four commercial coupling agents have slightly better reinforcing effect, while eTi4000 shows much better toughening effect. Moreover, the mCSW/PVC composite modified by eTi4000 shows higher storage modulus than those modified by commercial coupling agents in dynamic stress mode. The energy dissipation mechanism of these mCSW/PVC composites during the impact process was analyzed, and their interfacial interactions were evaluated quantitatively by the damping ratio. The mCSW/PVC composite modified by eTi4000 exhibits better thermal stability than their counterparts modified by the commercial coupling agents. Generally, eTi4000 is an effective coupling agent for CSW, and it can endow mCSW/PVC composites with better balanced properties.