高强超韧聚对苯二甲酸丁二醇酯/共聚酯合金的制备

Preparation of High Strength and Super Toughness PBT/Copolyester Alloy

采用熔融共混法制备了高强超韧聚对苯二甲酸丁二醇酯(PBT)/聚(对苯二甲酸乙二醇酯-co-对苯二甲酸-1,4-环己二醇酯)(PCTG)/甲基丙烯酸缩水甘油酯接枝POE(POE-g-GMA)共混物,并对其增韧机理进行了系统分析,同时利用高速相机记录了不同韧性材料的冲击行为.扫描电子显微镜(SEM)照片显示POE-g-GMA均匀分散在体系中,粒径约为0.3μm.PCTG和PBT具有很好的相容性,并能抑制PBT的结晶;随着PCTG含量的增加(0 wt%~40 wt%),共混物玻璃化转变温度(T_(g))呈线性增加,结晶度逐渐降低,但韧性增加不大.当PCTG含量为50 wt%时,材料发生脆韧转变,缺口冲击强度达到1060 J/m,断裂伸长率达到360%,分别较未添加PCTG的样品(PBT-3E)提高了17和20倍,且拉伸强度未有明显下降(45 MPa,下降了18%).冲击断面的微观形貌表明,在该含量下,材料发生了大量的空洞化和屈服形变.进一步分析表明,体系中更多的可移动无定形组分(MAF),更低的T_(g)和结晶度是材料发生脆韧转变的主要原因,而冲击瞬间产生的自发热,也进一步促进了材料屈服形变.最后通过仪器化冲击仪和高速相机记录了材料在脆性断裂和韧性断裂2种模式下形变随时间的关系,为进一步理解材料冲击行为提供了实验依据.

High-strength and super-toughened poly(butylene terephthalate)(PBT)/poly(ethylene terephthalate-co-terephthalate1,4-cyclohexanediol ester)(PCTG)/glycidyl methacrylate grafted POE(POE-g-GMA)blends were prepared by melt blending,and their toughening mechanisms were systematically analyzed.The impact behaviors of the materials with different toughness were recorded using a high-speed camera.Scanning electron microscopy(SEM)photographs showed that POE-g-GMA was uniformly dispersed in the blend with a particle size of about 0.3μm.PCTG possesses good compatibility with PBT,and could inhibit the crystallization of PBT.With the increase of PCTG content(0 wt%-40 wt%),the glass transition temperature(Tg)of the blends increased linearly and the crystallinity decreased gradually,but the toughness increases slightly.As the content of PCTG reaches 50 wt%,the brittle-ductile transition occurs,with the notch impact strength 1060 J/m and the elongation at break 360%,which is 17 and 20 times of PBT,respectively,but the tensile strength does not decrease significantly(45 MPa,decreased by 18%).The microscopic morphology of the impact fracture section shows that a large amount of cavitation and yield deformation occurred in the material at this content.Further analysis shows that more mobile amorphous fraction(MAF),lower Tg,and crystallinity are the main reasons for the brittle-ductile transformation of the material,and the heat generation at the moment of impact further contributes to the yield deformation.Finally,the deformation of the material with time in both brittle fracture and ductile fracture modes was recorded by an instrumented impact tester and high-speed camera to provide an experimental basis for further understanding of the impact behavior.