Preparation Of Modified Waterborne Polyurethane Membranes By Siloxane For Pervaporation

In this study, waterborne polyurethane(WPU) membranes were prepared from hard segments including TDI and IPDI and polyols oligomer as a kind of soft segments. And modified WPU membranes were gained subsequently after reacting with silane (KH-560/KH-550) with the intention of investigating the relationship between the content of silane and the properties of WPU membranes. The results are as follows.All membranes were benzene selective in pervaporation test. WPU membranes synthesized from lower molecular weight polyol presented better results, and polyester WPU obtained better affinity for benzene as compared with polyether WPU. The membranes with TDI as hard segment showed higher separation factor and lower flux than the membranes using IPDI as hard segment. As regards to the PBA-based membranes, the affinity for benzene decreased with the increase of the molecular weight of PBA. In addition, when the content of PBA was changed from 51.6% to 65.1%, the permeate flux of IPDI-based membranes increased from 0.28 kg.m-2.h’1 to 0.45 kg.m-2.h-1 little by little and their separation factor decreased from 4.91 to 4.64. While the result of membranes used TDI as hard segment was that their separation factor decreased from 6.11 to 5.33 and permeate flux was increased from 0.095 kg.m-2.h-1 to 0.42 kg.m-2.h-1.As to the modified WPU membranes, the permselectivity was enhanced after the addition of KH-560. With the increase of the ratio of KH-560 to -COOH from 0 to 5, the separation factor increased gradually, while the flux decreased due to strengthening of crosslinked network structure and increase of the polymer chain rigidity.The content of KH-550 also had an obvious effect on the properties of WPU membranes prepared by PBA-2000 and TDI. It showed that the separation factor tended to increase first and then decrease with the increase of KH-550, while the flux decreased gradually.