| The blend of Polycarbonate (PC) and Polybutyleneterephthalate (PBT) has excellent properties, it is one of the extremely greatest concerns of the composite material in recent years.However, it still has some problems, such as the transesterification&compatibility problems between PC and PBT, etc. All of these problems may make its mechanical performance and thermal stability performance degradate.For the above reasons, it still cannot meet the needs of the market applications,especially in automotive applications(such as the low temperature toughness,gas-assisted molding, etc). In this paper, the inhibition of transesterification, the blend compatibility and the automobile application properties were studied.Finally, the high-performance alloy of the different requirements was prepared.First, the properties under the different ratio of the PC/PBT were studied, the purpose was to find the reasonable design scope. By doing a series of experiments, we understood that the influence for different test projects were different, the effects on MI,impact strength and VICAT were larger, however the effect on tensile strength was smaller.The6/4～8/2range except for special cases(such as requiring high VICAT, etc)was thought the optimal target range, within this range, the alloy performance was stable, the alloy had good processability and modification was easily.Secondly, transesterification reaction was detailedly studied. The experiments involved different inhibitors,extrusion temperature and multi-extrusion and so on. The experimental results showed that the effects of MSP,AMSP were better, AMSP was the best. The0.1～0.4phr range was thought the optimal target range, the overall performance was the best at0.3phr.Experiments also found that, in addition to passivating residual titanium catalyst in PBT could inhibit the transesterification, SAG reacting with end-COOH of PBT was feasible method. The two methods could be used together in the practical application.The range of2%～5%was thought the optimal target range. This is also one of the findings in this paper.The inhibition effect of transesterification reaction was also verified by DSC and IR.The Tmc of the blend without inhibition disappeared,the Tmc of the blend with inhibition was visible. Tm was also improved after adding inhibitor.The absorption peak without was visible on1720.19cm-1and1770.26cm-1, the absorption peak showed on1714.68cm-1and1774.41cm-1, was closer to characteristic peak positions of the pure PC and pure PBT.The toughening and compatibilizing effects were studied. AX-8900was selected as modifier. The influence of the dosage was studied. AX-8900could severely reduce MI value. The influence on VICAT became apparent when the adding amount reached5phr. The low-temperature impact strength showed maximum when the adding amount reached3phr. Greater than this value, the impact strength decreases instead.The reason for this might be caused by poor compatibility. The results of the8840was even worse.Finally,the properties that the automobile industry cared (low temperature toughness, gas-assisted molding processability,chemical resistance, dimensional stability, weather resistance, fiberglass reinforced) were studied, and its influence factors were investigated. Such as the toughening effect of Silicone/Acrylic-rubber type toughening agents were better than ACR or BD, and Silicon content was higher,the toughening effect was better. The key of gas-assisted molding design was to guarantee material thermal stability and suitable viscosity. Ionic bond polymer could significantly improve the chemical resistance and physical properties(e.g. low temperature impact strength). Choosing masterbatch method would be better. About weather resistance, UV-234was excellent, but the dosage should be within1.2phr. About PC/PBT+10%GF, the75/25～65/35range was thought the optimal target range. The overall performance was the best in this range. |
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