成核剂对热致相分离法聚丙烯多孔膜结构及透过性能的影响

Effect of nucleating agents on morphology and permeability of iPP porous membranes via thermally induced phase separation

研究了等规聚丙烯i(PP)/邻苯二甲酸二丁酯(DBP/)邻苯二甲酸二-2-乙基己酯(DOP/)成核剂体系的热致相分离行为,成核剂为TM-I或己二酸.利用热台偏光显微镜测定试样的液-液相分离温度,采用示差扫描量热仪(DSC)测定成核剂的成核效应.通过控制冷却速率,加热模压制备iPP多孔膜,并对膜结构与透过性能进行了表征.发现当共溶剂组成和铸膜液固含量恒定时,加入少量成核剂,不影响体系液-液相分离温度,但动态结晶温度、晶粒尺寸、结晶速率、结晶范围、结晶度等结晶学参数发生变化;发现成核剂能改变多孔膜结构,并明显影响多孔膜的透过性能.

The behaviors of thermally induced phase separation for isotactic polypropylene （iPP） /Di-n-butyl phthalate （DBP）/Dioctyl phthalate （DOP）/nucleating agent systems were studied. TM-1 and adipic acid were used as nucleating agents, respectively. The liquid-liquid phase separation temperatures were determined visually by noting the appearance of turbidity under the optical microscope, and the isotherinel crystallization of iPP in the polymeric solution as investigated by using a differentical scanning calorimeter. Plate sheet porous membranes were prepared by moulding with heater, and with subsquent cooling. It is shown that the liquid-liquid phase separation temperature is hardly influenced by varying the addition of nucleating agent, while crystallization parameters, such as dynamic crystallization temperature, spherulite size, crystallization rate, crystallization scope, and crystallinity are changed. It is seggested that by choosing proper nucleating agent addition, the morphology of the resulting iPP porous membrane can be adjusted, and the permeability of the membranes can also be improved.