Study On Chain-extension Of PC And PET With Reactive Extrusion

The chain extending reaction extrusion of polycarbonate (PC) and polyethylene terephthalate (PET) was studied in this paper. In the study of polycarbonate chain extending, different kinds and quantities of additives were added to study the impact of chain extender on the PC. The effect of different processing conditions on the intrinsic viscosity of chain extender product was studied also. The study of PET flakes chain extended modification included effect of moisture content, chain extender, and process conditions of modification on the results of chain extension.First low viscosity polycarbonate (PC) was chosen as raw materials to be tested by IR and DSC. It was discovered that the polycarbonate (PC) used in the experiments was pure material. Detected by X-ray fluorescence spectroscopy, trace of impurities was found in it, but it didn't affect the results of reactive extrusion modification. It was showed that the average intrinsic viscosity of polycarbonate raw materials used in this study was 0.352dL.g-1 tested by the intrinsic viscosity.The most appropriate processing technology for modified polycarbonate was studied. It was found that the appropriate temperature of each section is:240℃,255℃,255℃,255℃, 240℃, the screw speed is 45rev/min.Using different types of chain extenders and additives for the polycarbonate chain extension by reactive extrusion modification, the results showed that when PMDA was chosen as chain extender, the most appropriate content of PMDA was 0.2%, at this time, the intrinsic viscosity of polycarbonate showed the largest increase which was 0.411dL.g-1. When the BOZ was added as chain extender, it had little effect on the chain extension, even reduced the viscosity of modified product characteristics. When adding 0.02% dicumyl peroxide (DCP), the [η] of product reached up to 0.423dL.g'1, improved significantly. It showed that the method of adding the appropriate peroxide-based chain extender to promote cross-linking micro-occurrence could improve the viscosity of PC chain extension product indeed. By adding isocyanate esters, the results showed that TDI gave slightly help in the process of PC chain extension modification.In subsequent experiments, high-viscosity PC was added into reaction, it was found that it improved the intrinsic viscosity of PC obviously. With the increase of PC content, a linear increase showed in intrinsic viscosity.By adding high viscosity PBT into the low viscosity PC for extended chain reaction, characterized by IR spectroscopy, it was found that PBT-b-PC copolymers formed between PBT and PC in the reaction, coincided with the formation of block copolymer and transesterification.When the moisture content of PET flakes was less than 2% in experimental extruder, the value of [η] floating around 0.8dL.g-1, it showed better effect. When the moisture content of PET flakes was more than 2%, the intrinsic viscosity decreased seriously.