Effect of on-line stretching treatment on the structure and performance of polyvinyl chloride hollow fiber membranes

In this work, polyvinyl chloride (PVC) hollow fiber membranes were prepared via a melt-spinning method and on-line stretching treatment. Gamma-butyrolactone (GBL) and epoxidized soybean oil (ESO) were selected as the solvent and the thermal stabilizer, respectively. The effects of on-line stretching treatment on the membrane structure and performance were characterized by means of morphology, surface roughness, pore size distribution, permeation performance and so on. The morphology showed that the prepared PVC hollow fiber membrane belonged to a homogeneous membrane. The on-line stretching treatment decreased the roughness of the inner surface and the outer surface, but it increased the water contact angle, mean pore size, porosity and pure water flux. Meanwhile, the pore size distribution range remained stable and narrow. The rejection of Direct Black 19 particles was higher than 90% when it approached a steady value. This type of membrane filtration was a deep intercept. Furthermore, the tensile strength increased with the increment of stretching ratio, and the elongation at break showed the opposite trend. The biggest tensile strength could be obtained as the stretching ratio reached 3.0 and was 23.89 MPa.