Synthesis of a New Titanate Coupling Agent for the Modification of Calcium Sulfate Whisker in Poly(Vinyl Chloride) Composite

A new titanate coupling agent synthesized from polyethylene glycol (PEG), isooctyl alcohol, and phosphorus pentoxide (P₂O₅) was used for the modification of calcium sulfate whiskers (CSWs) and the preparation of high-performance CSW/poly(vinyl chloride) (PVC) composites. The titanate coupling agent (sTi) and the modified CSWs (sTi-CSW) were characterized by Fourier transform infrared (FTIR) spectroscopy, and the mechanical, dynamic mechanical, and heat resistant properties and thermostability of sTi-CSW/PVC and CSW/PVC composites were compared. The results show that sTi-CSW/PVC composite with 10 wt. % whisker content has the best performance, and its tensile strength, Young's modulus, elongation at break, break strength, and impact strength are 67.2 MPa, 1926 MPa, 233%, 51.1 MPa, and 12.75 KJ·m-2, with an increase of 20.9%, 11.5%, 145.3%, 24.6%, and 65.4% compared to that of CSW/PVC composite at the same whisker content. As the whisker content increases, the storage modulus increases, the Vicat softening temperature decreases slightly, and the glass transition temperature increases at first and then decreases.