动力学因素对热诱导相分离法制备亲水性乙烯-丙烯酸共聚物微孔膜结构的影响

选择 3种不同丙烯酸含量的乙烯 丙烯酸共聚物 (EAA)为原材料 ,二苯醚 (DPE)为稀释剂 ,研究了淬冷温度、粗化时间等影响液滴生长的动力学因素对热诱导相分离法 (TIPS)制备EAA DPE亲水性高分子微孔膜结构的影响 .淬冷温度的高低决定了EAA DPE体系是发生液 液相分离还是固 液相分离 ,而产生相分离的机理不同将影响稀释剂液滴的生长 ,最终影响微孔膜的孔径 .实验结果表明 ,在相同粗化时间的条件下 ,随着EAA1 41 0 DPE、EAA3 0 0 2 DPE、EAA3 0 0 3 DPE三体系冷却温度的逐渐升高 ,孔径逐渐变大 .在结晶温度以下 ( 0℃、3 0℃、60℃ )粗化时间相同时 ,温度对微孔膜的孔径影响较小 ,例如 0℃和 3 0℃的恒温条件粗化 1 0min,微孔膜的孔径在 1～ 3 μm之间 ;在 60℃的恒温条件粗化 1 0min ,微孔膜的孔径在 3～ 5 μm之间 .而在 90℃的恒温条件粗化相同的时间 ,由于体系始终处于结晶温度线以上 ,体系始终处在液 液相分离区域 ,最终得到微孔膜的孔径达到了 6～8μm .在结晶温度以下 ( 3 0℃ )进行恒温粗化 ,由于体系的过冷程度很大 ,液滴相的粗化过程被抑制住 ,所以粗化时间对微孔膜的孔径影响不大 ;而在结晶温度以上 ( 90℃ )进行恒温粗化时 ,则是随着粗化时间的延长 ,微孔膜的孔径逐渐变大

THE EFFECT OF KINETIC FACTORS ON THE STRUCTURE OF THE HYDROPHILIC ETHYLENE-ACRYLIC ACID COPOLYMER MICROPOROUS MEMBRANES PREPARED VIA THERMALLY INDUCED PHASE SEPARTATION

The effects of kinetic factors of phase separation,such as coarsening time and quenching temperature,on the hydrophilic microporous membranes were studied via thermally induced phase separation(TIPS) process using three hydrophilic ethylene acrylic acid co polymers(EAA) with different co unit contents and diphenyl ether(DPE). The coarsening time and quenching temperature were used to influence the phase separation of the three different EAA/DPE systems,their diluent droplets growth,membrane cell size and crystalline structure. The mechanism of phase separation,liquid liquid or solid liquid made,was determined by the quenching temperature. For EAA/DPE systems liquid liquid phase separation occurred when the quenching temperature was above the crystalline temperature of EAA,and solid liquid phase separation occurred when the quenching temperature was below the crystalline temperature of EAA. The experimental results showed that the membrane pore size of the EAA/DPE systems was increased with increasing the quenching or cooling temperature. The average size of the cells was 1～3?μm,3～5?μm and 6～8?μm for samples with a same coarsening of time of 10?min,but differernt quenching temperatares 30℃,60℃ and 90℃,respectively. At the quenching temperature of 30℃,the droplet phase in EAA/DPE systems hardly grew because the temperature was below the crystalline temperature of EAA. The diluent droplet growth was restricted by the high viscosity of the system and the crystalline structure of EAA co polymer. While at 90℃,it is above the crystalline temperature of EAA co polymer,a dramatic increase of droplet size occurred with the coarsening time in the begining,and after 8 min the size kept almost unchanged.