Preparation and Flammability of a Flame-Retardant Poly(Butyl Acrylate-Vinyl Acetate) System Based on Gemin-Surfactant Modified Montmorillonite and Ammonium Polyphosphate

Gemin-surfactant modified montmorillonite (G-MMT) was successfully prepared by an ion exchange reaction and characterized via Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The P(BA-VAc)/G-MMT emulsion was prepared via an in-situ polymerization method using potassium persulfate (K2S2O8, KPS) as an initiator. Ammonium polyphosphate (APP) was introduced for obtaining P(BA-VAc)/APP/G-MMT flame-retardant latex with a constant total content of 15wt% of APP and G-MMT in P(BA-VAc). The flame retardancy and thermal behavior of the latex films were investigated by limiting oxygen index (LOI), vertical burning test (UL-94) and thermal gravimetric analysis (TG/DTA). Compared with the P(BA-VAc)/APP composite, the LOI value of P(BA-VAc)/APP/G-MMT containing 0.5wt% G-MMT at the same total additive loading increased to 29.1 from 20.0 and its UL-94 increased from no rating to V-0. Thermal gravimetric (TG) data showed that the amount of residues increased significantly with the loading of G-MMT. In addition, the LOI values increased with the increase in char residues. The morphology and microstructure of the residues generated during LOI testing were investigated by scanning electron microscopy (SEM). The outer surfaces of P(BA-VAc)/APP/G-MMT charred layers were more continuous and compact than those of P(BA-VAc)/APP.