Abstract:The waste silicone rubber not only pollutes the environment, but also causes great waste. How to recycle these wastes is an urgent problem to be solved. The silicone rubber was modified by the treatment of acidification and the hydrosilylation reaction, and was applied into the flame retardant poly (lactic acid) (PLA). The effects of silicone rubber modified before and after on the thermal properties and flame retardant properties were studied comparatively by thermogravimetry, limited oxygen index (LOI), vertical burning tests and cone calorimetric tests. The results show that the modified silicone rubber (H-WSiRC) has high thermal stability. The LOI value of the flame retardant PLA containing H-WSiRC reaches 33 and the UL94V0 level is achieved; the heat release peak and total heat release are 187 kW/m2 and 36 MJ/m2, the amount of residual char reaches 35.3%. The data means that the promotion of H-WSiRC for the flame retardancy of PLA is better than that of the unmodified silicone rubber.