【作者】 伍雄俊；

【导师】 黄汉雄；

【作者基本信息】 华南理工大学 ， 机械设计及理论， 2010， 硕士

【摘要】 原位微纤化作为一种重要的提高聚合物共混物力学性能的方法而受到广泛的关注。本文通过在单螺杆挤出机中引入不同的加工流场,挤出制备聚丁二酸丁二醇酯(PBS)/聚丙烯(PP)和低密度聚乙烯(LDPE)/PP两种原位微纤化共混物,研究流场-分散相形态-动态流变性能三者之间的关系。采用单螺杆挤出机配备狭缝机头(主要施加剪切流场)制备PBS/PP(85/15)原位微纤化共混物。研究发现,随加工温度的降低,分散相液滴的平均直径和数量减小,分散相纤维的平均直径减小、数量增多;随螺杆转速的提高,分散相纤维的平均直径减小、数量增多。当机头温度170℃和螺杆转速80rpm时,形成的PP纤维的平均直径最小,为2.98μm。采用普通和交替螺杆挤出机(分别主要施加剪切和混沌混炼流场),以沿程取样的方式制备PBS/PP(85/15)共混物。研究发现,后者制备的PBS/PP共混物中分散相纤维的平均直径较小,分散相液滴的分散指数较高、分维数较低。螺杆转速的提高可以明显地降低分散相液滴和纤维的平均直径。随分散相纤维含量的增加,PBS/PP共混物的复数黏度、储能模量和损耗模量增加。螺杆转速50rpm时,靠近交替螺杆挤出机出口处制备的PBS/PP共混物的储能模量-频率和损耗模量-频率关系曲线在低频区表现出“类固”响应,表明分散相PP形成了网状结构。采用多边螺槽对流式单螺杆挤出机(主要施加混沌混炼流场)与单螺杆挤出机串联的方法,制备LDPE/PP(90/10、80/20和70/30)共混物。研究发现,PP含量为10wt%时,分散相主要呈液滴状,没有形成纤维;PP含量为20wt%时,形成的分散相纤维平均直径为1.98μm;PP含量为30wt%时,分散相纤维的平均直径最小,为0.69μm。时-温叠加曲线表明,LDPE/PP共混物中没有发生相分离;Han曲线表明,随PP含量的增加,LDPE/PP共混物中分散相PP的尺寸均匀性变差。更多还原

【Abstract】 As one of the most important methods to increase the mechanical properties of polymer, in-situ fibrillation has attracted a great deal of interests. In this study, poly(butylene succinate)/polypropylene (PBS/PP) and low density polyethylene/polypropylene (LDPE/PP) in-situ microfibrillar blends are prepared in different fluid fields using a single screw extruder, and the relationship among the fluid field, morphology, and rheological properties is studied.PBS/PP (85/15 w/w) in-situ microfibrillar blends are prepared using a single screw extruder equipped with a slit die, which provides a shear mixing field. The results show that the average diameter and amount of PP droplets decrease, the average diameter of PP fibres decreases and their amount increases as the processing temperature decreases. The average diameter of PP fibres decreases and their amount increases as the screw speed increases. The PP droplets in the blend prepared at die temperature of 170℃and screw speed of 80rpm have a minimal average diameter, which is 2.98μm.PBS/PP (85/15 w/w) blends are prepared along a single screw extruder with a shear mixing field and chaotic mixing field, respectively. The results show that it can form smaller average diameter of PP fibres, higher dispersion parameter of PP particles, and lower fractal dimension of PBS/PP blends using the later extruder. Complex viscosity, storage modulus, and loss modulus are increased as PP concentration increases. The storage modulus and loss modulus of PBS/PP blends near the die exit prepared by the extruder with the chaotic mixing field at screw speed of 50rpm present a solid-like response at lower frequencies. It means that PP forms network structure.LDPE/PP (90/10, 80/20, and 70/30 w/w) blends are prepared using a single screw extruder plus HP extruder. The results show that PP can not form fibres with the PP concentration of 10wt%, form fibres of 1.98μm with the PP concentration of 20wt%, and form fibres of 0.69μm with the PP concentration of 30wt%. Time-temperature superposition (TTS) curve show that no phase separation appears in LDPE/PP blends. Han plots show that the size of PP becomes less homogeneous as the increaseing of PP concentration in LDPE/PP blends.更多还原