二步共混法制备PBAT/PGA材料及其性能

Preparation and properties of PBAT/PGA blends with two-step blending method

采用二步共混法制备改性聚己二酸/对苯二甲酸丁二酯/聚乙醇酸(PBAT/PGA)共混物,其中,添加多元环氧化合物(ADR)为扩链剂和反应增容剂。首先通过第一步高温熔融共混(235℃),制备得到PBAT/PGA二元预混物;随后添加ADR进行低温共混(170℃),最终得到(PBAT/PGA)/ADR二步法共混物。并采用常见的一步共混法来制备同样配比的PBAT/PGA/ADR共混物作为比照。研究不同加工方式和ADR添加量对共混物流变行为、微观形貌和拉伸性能等方面的影响。结果表明,采用二步共混法,可在保持较大PGA分散相尺寸的同时,又能兼顾改善PBAT/PGA两相界面相容性。相对于PBAT/PGA(65/35)二元共混物和一步法共混物,二步法共混物在拉伸屈服强度、拉伸弹性模量和断裂伸长率方面具有更为均衡的性能。如当ADR添加量为0.8份时,(PBAT/PGA)/ADR(65/35/0.8)二步法共混物的拉伸屈服强度、拉伸弹性模量和断裂伸长率可分别达到11.57 MPa,160.88 MPa和309.5%。此外,测试结果表明,相对于二步法共混物,ADR的扩链/支化反应对一步法共混物流变行为的影响更为显著。

Blend of poly(butylene adipate-co-terephthalate)/polyglycolic acid(PBAT/PGA)were prepared by two-step blending method,where multi-component epoxy compound(ADR)was used as a chain extender and reactive compatibilizer.First,the binary pre-mixture of PBAT/PGA was obtained through melt blending at a higher temperature of 235℃,and then ADR was added into the PBAT/PGA blend with a lower blending temperature of 170℃.As a result,the two-step blends of PBAT/PGA/ADR were prepared successfully.PBAT/PGA/ADR blends with the same ratios prepared by the common one-step blending method served as a comparison.The effects of different processing methods and ADR content on the rheological behavior,microstructure and tensile performance of the blends were investigated in detail.The results indicate that the two-step blending method could maintain a larger size of the PGA dispersion domains while simultaneously improving the interfacial compatibility between PBAT matrix and PGA domains.Compared to the binary PBAT/PGA(65/35)blends and the blends prepared by the one-step blending method,the blends prepared by the two-step blending method exhibit more balanced properties in terms of tensile yield strength,tensile modulus,and elongation at break.For instance,with an ADR content of 0.8 phr,tensile yield strength,tensile modulus,and elongation at break of(PBAT/PGA)/ADR(65/35/0.8)blend could reach 11.57 MPa,160.88 MPa,and 309.5%,respectively.Furthermore,the testing results demonstrate that the chain extension/branching reaction of ADR has a more significant impact on the rheological behavior of the blends prepared by the one-step blending method compared to the ones prepared by the two-step blending method.