Effect of compatible nucleation seeds on the morphology of porous Nylon 6 membrane

摘要

Recent study has revealed that when the nucleation takes place by adding compatible particles in Nylon 6 medium, it is possible to change greatly the nucleation intensity and the growing speed of crystallites. The present work demonstrates the employment of compatible PPO which was prepared by reactive blending of PPO and Nylon 6. A compatible phase of PPO was dispersed in meta-solution containing Nylon, formic acid and water. Dopes in meta-solution condition were prepared by varying the quantity and compatibility of dispersed PPO phase. It was observed that the morphology of membranes was dependent on the number of dispersed PPO. Firstly, the quantity of growing crystallite numbers initiated in such meta-solution dopes was much more than that when there is no compatible dispersed PPO in dopes. The resultant structure of membranes is due to kinetic mechanism of nucleation in addition to the thermodynamic phase behavior, both of which are prevalent for membrane formation process. Secondly, different compatibility between PPO and Nylon 6 results in different size of dispersed PPO phase in blends. Therefore even with the same weight fraction of PPO, different compatibility gives different quantity in number of dispersed PPO in meta-solution dopes and thus produces different effects of nucleation induction. The better is the interface compatibility of original blend, the greater will be the initial nucleation and thus, the porosity of the structure of membranes will increase.