Dynamic rheological property and membrane formation of mechanochemically modified polyvinylchloride

Abstract

Polyvinylchloride (PVC) was mechanochemically modified (mmPVC) by a ball mill. The dynamic rheological properties of PVC and mmPVC dope solution [containing PVC/N,N-dimethyl acetamide (DMAc)/polyethylene glycol 400 (PEG 400)/polyethylene glycol 6000 (PEG 6000)] were studied with the advanced rheometric expansion system of AR1000 at different temperatures (40, 60, and 80 °C). PVC and mmPVC membranes were prepared at different dope solution temperatures (50 and 80 °C), and the structure and permeation of membranes were analyzed. It was showed that homogeneous degree of PVC dope solution deteriorated as temperature increased; while homogeneous degree of mmPVC dope solution improved at 80 °C. Mechanochemical modification led to the forging of hydroxyl group into PVC molecular chains, and the storage modulus (G′) of modified PVC dope solution increased. The gel point of mmPVC dope solution occurred at 77.3 °C, and the viscosity (η) increased significantly. As the dope solution temperature increased, the permeation of PVC membrane increased from 158.8 to 236.7 L/(m2 h); while the permeation of mmPVC membrane decreased from 349.2 to 302.3 L/(m2 h).