Research Of The Properties Of Flame-retardant Flexible Polyvinyl Chloride (PVC)

In the paper, we investigated the effect of nine flame retardants on the flame retardancy and mechanical properties of flexible polyvinyl chloride (PVC). These flame retardants are antimony oxide (Sb2O3), ammonium polyphosphate (APP), Bisphenol-A Bis(Diphenyl Phosphate)(BDP), Silicones, organic montmorillonite (OMMT), aluminum hydroxide (ATH), magnesium dihydroxide (MDH), zinc stannate (ZS) and zinc borate (ZB),which were added individually to flexible PVC. The results showed that when Sb2O3or ZS in addition amount was1-4, the PVC blends have obvious retarding effect. The other seven kinds of flame retardants, at amount of10to50phr in flexible PVC, can improve the oxygen index properties of flexible PVC, and oxygen index increased along with the increase of the dosage of the flame retardants.In this paper, stearic acid, γ-aminopropyl triethoxysilane (KH550), aluminate coupling agent were applied in the modification of ATH. It showed that stearic acid was better surface modification agent.The binary synergy between modified ATH and other flame retardants in flame-retardant PVC is researched. Research results found oxygen index increased gradually with the increasing dosage of aluminum hydroxide, when the dosage of the other seven kinds of flame retardant was fixed to3phr. The results showed that BDP, ZS, ZB, OMMT, Silicones have synergistic flame retardant effect with aluminum hydroxide.It was studied that the synergism of ternary systems of flame retardants have good inflame-retarding effect for flexible PVC, based on binary system above. Though the oxygen index test, smoke density test, mechanical properties test, thermogravimetric analysis, carbon residue SEM, the results show that the four kinds of ternary systems, Sb2O3/ATH/ZB, BDP/ZS/ATH, BDP/ATH/Silicones, OMMT/ATH/APP all have synergistic flame retardant effect. The amount of ATH for20-30phr and other composite flame retardant fixed to3phr, the flexible PVC products has high oxygen index, low smoke density and better mechanical properties.