Simultaneously enhanced flame retardancy and smoke suppression properties of flexible polyvinyl chloride with the incorporation of modified Mg(OH)2 and Sb2O3

High flammability and dense smoke constitute the two major issues limiting the extensive application of flexible polyvinyl chloride (PVC) materials. Facing these issues, the anti-flammability and smoke suppression performances of flexible PVC materials with magnesium hydroxide (Mg(OH)2), antimony trioxide (Sb2O3), and their mixtures were investigated, accompanied with the surface modification of Mg(OH)2 using stearic acid. With 50 phr loading, modified Mg(OH)2 endowed PVC matrix with better flame retardancy, smoke suppression, and mechanical properties compared to unmodified Mg(OH)2. The combination use of modified Mg(OH)2 and Sb2O3 can significantly enhance the flame retardancy and smoke suppression of PVC at the same time, unlike the standalone use of modified Mg(OH)2 and Sb2O3. When PVC blended with 50 phr modified Mg(OH)2 and 1 phr Sb2O3, the limiting oxygen index increased from 28.1% to 31.7%, the smoke density rating, peak heat release rate, and total smoke production decreased by 33%, 41%, and 40%, respectively. Moreover, the quality and compactness of char residues were noticeably improved compared with those of pure flexible PVC. Meanwhile, the flame retardants didn't obviously diminish the mechanical properties of PVC which benefited the practical applications of PVC material.