Study On Toughening And Flame Retarding Modification Based On Recycled Polycarbonate

Toughening and flame retarding modification for recycled polycarbonate (PC) was studied by using core-shell structured silicon rubber. The mechanical properties, flame retardance, fracture surface morphology, and thermal stability of the recycled PC blends were investigated. Result showed the recycled PC blends cannot be toughened due to the incompatibility between the PC and core-shell structured silicon rubber. However, the notched impact strength can only be improved significantly with the epoxy resin or styrene maleic anhydride copolymer (SMA) as a compatibilizer, and epoxy resin was more useful than SMA. The compatibilizer can enhance the interfacial adhesion between two phases and reduce the interfacial tension. The fracture surface morphology presented that compatibilizer can introduce rubber particles homogeneous distribution in PC matrix which was the key factor to the excellent toughening effect. Besides, the core-shell structured silicon rubber could enhance the flame retardant as well as toughen the recycled PC significantly. In the burning process, the silicon rubber could moved to the PC surface fast, and formed a high flame retardant carbon protection layer; it formed cross linking structure between PC matrix and silicon rubber to act flame retardant for the recycled PC. So the blends containing 7 wt.% core-shell structured silicon rubber and 3 wt.% compatibilizer can achieve a UL94 V-0 rating in vertical burning test.Moreover, toughening and strengthening modification for recycled PC was studied by using rigid polystyrene (PS) particles, which refractive index was similar to PC. The transparency, mechanical properties, compatibility and thermal stability of the recycled PC blends were investigated. Result illustrated the recycled PC blends still had the excellent transparency but they cannot be toughened due to incompatibility between the PC and PS. However, they can be toughened and strengthened as a result of the rigid organic particles toughening and strengthening effect with SMA as a compatibilizer. The SMA which refractive index was also similar to PC and PS can also improve the transparency of blends. The SMA not only improved the compatibility between the PC and PS but also enhanced the thermal degradation temperature of blends which made they obtained a good thermal stability. So when the proportion of PC/PS/SMA blends was 93/7/7 can attain the best mechanical properties and a fine comprehensive performance.