Preparation and Properties of UHMWPE/Si02 Hybrid Hollow Fibre Membranes via Thermally Induced Phase Separation-stretching Method

Ultrahigh molecular weight polyethylene (UHMWPE)/Si0 2 hybrid hollow fibre membranes were prepared by thermally induced phase separation-stretching (TIPS-S), using mineral oil as diluent and Si02 as additive. In this study, UHMWPE/ Si02 blends were incompatible. Therefore , an interfacial microvoid was produced in the interface between UHMWPE and Si02 after stretching along fibre axis. Secondly, the stretching pore also appeared due to stretch. Moreover, UHMWPE/minera l oil was blended into a homogeneous phase at sufficiently high temperature and underwent phase separation when it was cooled. The TIPS pore was prepared by extracting mineral oil. Thereby, after stretching, multi-pore-structure (MPS) including interfacial microvoid , stretching pores, and pore by TIPS was built. The influential factors, including heat-treatment, draw ratio and drawing temperature were investigated. The results of this study indicated that the draw ratio had an optimum value in order to obtain the UHMWPE/Si02 hybrid hollow fibre membranes with good permeability. The permeability of membrane showed the best performance at the 5 fo lds draw ratio. Theeffects of heat-treatment and drawing temperature on pore structure have been mainly produced from the pores contraction and defect formation. Both the pore size and the pore number of HCs were the highest, those of Cs took second place and those of HH5 were the lowest. HCs showed the highest pure water flux compared to HHs and Cs. The mechanical properties of membranes were the result of a set of factors including crystallinity, degree of orientation, and defects in the membrane structure .