PBS与PLLA双螺杆挤出共混体系的相容性、结晶与性能分析

Analysis on the Compatibility,Crystallization and Performance for PBS and PLLA Blends Using Screwing

将聚丁二酸丁二醇酯(PBS)与聚乳酸(PLLA)通过熔融挤出的方法共混,研究二者的相容性、形貌、结晶及力学性能.结果表明,PBS与PLLA是完全不相容的.随着两组分相对质量含量的变化,共混物的形貌由一种组分组成的连续相(PBS)、另一种组分为分散相的海岛状(PLLA)形态变为双连续相,再到另一种海岛状(PBS)的形态结构.这种形态结构影响了PBS的结晶与力学性能.当PBS质量含量较低时,由于不同PBS微区引起成核杂质的活性不同,PBS发生了分级结晶,形成更细的晶体,相应共混物的断裂伸长率提高.但是PBS与PLLA的共混物的拉伸强度和模量由PLLA的质量含量主导,与PLLA的质量含量的增加呈正相关性.PBS与PLLA共混物的动态模量由于受两组分的结晶、玻璃化温度及结构的影响而呈现出复杂的变化.

Blending is one of the important methods in improving the performance and broadening the application scope of polymers. Studies on the compatibility, morphology, crystallization and mechanical performance for the blends of poly（butylenes succinate）and poly（L-lactide）were carried out in this section. PBS and PLLA are incompatible,leading to a variation of the morphology from a sea-island structure to discontinuous structure and then to another sea-island structure with increasing the PLLA content. The structure had great effects on the crystallization and mechanical behaviors of PBS. For blends with low PBS contents, PBS was a dispersed phase in different independent micro-domains, leading to fractional crystallizations of PBS due to impieties with different activities in different micro-domains. The tensile modulus and strength of the blend increased with the increasing of PLLA content. The break elongation at break of the blends containing a small amount of PBS was higher than pure PBS, PLLA and other blends. The dynamic storage modulus of PBS/PLLA blends showed a complex variation trends due to the difference of the glass transition temperature and crystallization properties between the two components.