Preparation of aluminum hydroxide/aluminum phosphinate flame-retardant poly(vinyl alcohol) foam through thermal processing

A novel flame-retardant poly (vinyl alcohol) (PVA) composite foam was prepared successfully through thermal processing, which was filled with high content of flame retardant, based on aluminum hydroxide (ATH) and aluminum phosphinate (AlPi) and using water as plasticizer and blowing agent. The flame-retardant property and mechanism of the prepared foam matrix were studied by vertical burning test, limiting oxygen index (LOI), cone calorimeter, scanning electronic microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The experimental results showed that the PVA/ATH/AlPi (1/1.2/0.05) composite achieved LOI value of 41% and UL94 V-0 (3.2 mm) rate. The addition of ATH and AlPi into PVA matrix significantly decreased flammability of the composites, because a more compact and continuous char layer of the PVA/ATH/AlPi composite could be formed, due to the involvement of AlPi in the char-forming reaction. Compared with the pure PVA sample, the peak heat release rate (PHRR) and total heat release (THR) of PVA/ATH/AlPi (1/1.2/0.05) composite were reduced by 76.5% and 58.2%, respectively. Built upon this PVA-based foam matrix with good flame retardancy, the flame-retardant PVA-based foam was successfully prepared through thermal extrusion. In addition, the influence of water content on melt viscosity, foam structure and mechanical strength was also analyzed. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42020.