Effects of polyether titanate coupling agent on the flame retardancy and mechanical properties of soft poly(vinyl chloride)/basic magnesium carbonate composites

Abstract

AbstractIn this paper, a new polyether titanate coupling agent (Ti4000) was used to modify basic magnesium carbonate (BMC), and Ti4000 modified BMC (Ti4000‐BMC) was characterized by X‐ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray photoelectron spectroscopy. Then, PVC composites were prepared by adding BMC or Ti4000‐BMC into soft PVC matrix via melt blending, and their flame retardancy was examined by limiting oxygen index (LOI), UL‐94 test, and cone calorimeter test. The results show that BMC can effectively improve flame resistance and suppress smoke production of pure soft PVC. As a result, the LOI is increased from 23.9% for pure soft PVC to 29.2% for Ti4000‐BMC/PVC composite with 50 phr Ti4000‐BMC (50%Ti4000‐BMC/PVC), and the composite passes the V0 rating in UL‐94 test, the peak heat release rate, total heat release, peak smoke production rate, and total smoke production are decreased from 343.10 kW/m2, 94.50 MJ/m2, 0.17 m2/s, and 27.20 m2/kg for pure soft PVC to 234.20 kW/m2, 70.20 MJ/m2, 0.02 m2/s, and 2.30 m2/kg for 50%Ti4000‐BMC/PVC composite, respectively. The analysis of char residues suggests that Ti4000‐BMC/PVC composites form the most compact char layer structure, indicating that the soft PVC composites show better char forming ability. In addition, the yield strength is increased from 4.4 MPa for pure soft PVC to 12.9 MPa for 50%Ti4000‐BMC/PVC composite, with an increase of 193.2%, and it shows good reinforcement effect on the soft PVC matrix.