| Polycarbonate/acrylonitrile-butadiene-styrene copolymer blend, which is widely used in automotive, machinery, communication tools and many other fields, is the first one of PC-contained blends in industry. Unfortunately, PC/ABS blend is poor in flame retardancy as ABS was introduced, which is rather flammable. Therefore, to develop flame retarded PC/ABS blend is the key point of PC/ABS blend. To ensure environment-friendly and flame retarded efficiency, phosphate flame retardant in halogen-free flame retarded PC/ABS blend is widely applied. Besides, the clay flame retardant system has become one of the most important research fields of flame retardant. Based on the flame retardant mechanism of phosphate in PC/ABS blend, effects of kinds of modified montmorillonite on phosphate flame retarded PC/ABS blends were discussed.Two kinds of organic montmorillonite (OMMT) were prepared by modifying Na-montmorillonite (Na-MMT) with quaternary phosphonium salt or bisphenol-A bis(diphenyl phosphate). Effects of OMMT on the thermal properties and flame retardancy of phosphate flame retarded PC/ABS blend were investigated. TEM results indicated that the dispersion of OMMT particles were better than Na-MMT. TG analysis showed that OMMT decreased the thermal stability of flame retardant PC/ABS blends in nitrogen atmosphere. However, the thermal stability had increased in air atmosphere, and the yield of residues increased. When introducing OMMT into phosphate flame retardant PC/ABS blend, the rate of UL94test became V2due to dropping, and the limiting oxygen index (LOI) value did not improved. On the other hand, incorporating BDP modified MMT (BDP-MMT) with phosphate flame retardant PC/ABS blend made the combustion behavior flattens out and reduced the second peak of heat release rate (PHRR2). owing to the formation of more solid and compact char residue.Four kinds of metal ion-treated montmorillonite (m-MMT) were prepared by exchanging Na*of Na-MMT with different transition metal ions (Fe3-. Cu2-, Zn2-and Co2+). Effects of m-MMT on the thermal properties and flame retardancy of phosphate flame retarded PC/ABS blends were investigated. TG analysis showed that m-MMT enhanced the thermal properties and char residues in nitrogen atmosphere. Besides, m-MMT increased the initial decomposition temperature and the yield of residues in air atmosphere. Constant temperature TG analysis showed that in air atmosphere, m-MMT delayed the formation of carbon layer in low temperature but improved the thermal stability of char layer in high temperature. Incorporating m-MMT with phosphate flame retardant PC/ABS blend, the time to the secondary combustion (PHRR2) delayed. Fe3+modified MMT can increase the LOI value and reduce the burning time in UL94test.Three kinds of acid-treated montmrillonite (a-MMT) and a kind of alkali-treated montmrillonite (b-MMT) were prepared by modifying Na-montmorillonite (Na-MMT) with hydrochloric acid or sodium hydroxide. Effects of MMT on the thermal properties and flame retardancy of phosphate flame retarded PC/ABS blend were investigated. TG analysis showed that in the nitrogen atmosphere. BDP modified montmorillonite (BDP-MMT) declined the thermal stability of flame retardant PC/ABS blends and decreased the yield of residues, while a-MMT and b-MMT increased the initial decomposition temperature and the yield of residues. Microscale combustion calorimeter showed that BDP-MMT worsen the barrier property of carbon layer. Incorporating a-MMT and b-MMT with phosphate flame retardant PC/ABS blend, the thermal stability of carbon layer increased and the time to the secondary combustion (PHRR2) delayed. On the other hand, when introducing MMT into phosphate flame retardant PC/ABS blend, the values of LOI decreased. Tensile testing showed that MMT increased the tensile strength of flame retardant PC/ABS blends. |
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