The porous polyvinylidene fluoride hollow fiber membranes were prepared via the thermally induced phase separation process using mixed diluent. The effects of take-up speed on the structure of membranes were investigated by scanning electron microscopy, differential scanning calorimetry, and wide-angle X-ray diffraction. The membrane properties were measured in terms of the pure water flux, porosity, and mechanical properties. The results showed that the cross-sectional structure of membrane had an obvious change and presented a uniform structure when TS increased to 72 m min⁻¹, whereas the membrane made from TS <41 m min⁻ presented an interconnected aggregation structure. However, the change of surface structure of all membranes was hardly observed. In addition, the strength and elongation of breakage of membrane increased obviously with the increase of TS, whereas the pure water flux and porosity changed slightly. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A novel method of preparing polytetrafluoroethylene (PTFE) hollow fiber membrane was presented by utilizing poly (vinyl alcohol) (PVA) can form a gel of two dimensional complex compounds with Boric acid (H₃BO₃). Effects of H₃BO₃ on PTFE nascent hollow fiber were investigated, and the results showed that the introduction of H₃BO₃ effectively reduced the addition of PVA. The configuration named “fibril” formed between PVA and H₃BO₃ could be observed in nascent hollow fiber by SEM (Scanning electronic microscopy). Furthermore, Calcium carbonate (CaCO₃) particles (60 nm∼ 90 nm) were introduced into PTFE matrix. The interfacial microvoids (IFMs) which were different from the PTFE sintering or node-fibril network structure were obtained. The assumption of the IFMs formation was proposed in this study. Effects of CaCO₃ amount and draw ratios on structure and properties of hybrid hollow fiber membranes were analyzed, and the SEM results showed that the IFMs quantity and diameter improved with draw ratio increasing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Poly(tetrafluoroethylene) (PTFE)/calcium carbonate (CaCO₃) hybrid porous membranes were prepared from a mixture of PTFE emulsion and nanoscale CaCO₃ particles by using polyvinyl alcohol as the fiber forming polymer. The interfacial microvoids (IFMs) were obtained owing to the different mechanical properties of PTFE and CaCO₃. Effects of CaCO₃ contents and membrane draw ratios on membranes structure and properties were investigated. Results showed that: (1) as the CaCO₃ content increase, the membrane hydrophobicity improved owing to the increasing of membranes surface roughness, (2) the membrane porosity and pure water flux increased as the CaCO₃ content and membrane draw ratios increasing. By the membrane morphology configuration with scanning electron microscopy, it was found that the IFMs quantity and pore size improved obviously with the draw ratios increasing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Porous, flat membranes of ultrahigh-molecular-weight polyethylene (UHMWPE) were prepared by thermally induced phase separation, with mineral oil as a diluent and poly(ethylene glycol) with a weight-average molecular weight of 20,000 (PEG20000) as an additive. Through the control of the rheological behavior, crystallite size, and pore structure, the influential factors, including the diluent, poly(ethylene glycol) (PEG) content, and cooling rate, were investigated. The results suggested that PEG could decrease the viscosity of UHMWPE/diluent apparently. The crystal density decreased when mineral oil was added, which made the melting point and crystallinity of UHMWPE lower. The crystallization rate and crystallinity also increased with the addition of PEG. However, the addition of excess PEG restrained crystal growth. PEG20000 in membranes could be extracted absolutely through the soaking of the membranes with fresh water for 7 days. With increasing PEG content, both porosity and pure water flux first increased and then decreased, reaching a maximum at a PEG mass fraction of 10%. The cooling rate had a direct effect the crystal structure. A slow cooling rate was good for crystal growth and diluent integration. Therefore, the pure water flux increased along with the temperature of the cooling medium, whereas porosity first increased and then decreased, reaching a maximum at 40°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

In this study, poly(n-butyl methacrylate) (PBMA) was prepared by a suspension polymerization process, and blending with polyacrylonitrile (PAN) in N,N-dimethyl acetamide to prepare PAN/PBMA blends in various proportions. Hansen's three dimensional solubility parameters of PAN and PBMA were calculated approximately through the contributions of the structural groups. The compatibility in these blend systems was studied with theoretical calculations as well as experimental measurements. Viscometric methods, Fourier transform infrared spectroscopy, dynamic mechanical analysis, scanning electron microscopy, and thermogravimetric analysis were used for this investigation. All the results showed that a partial compatibility existed in PAN/PBMA blend system, which may be due to the intermolecular interactions between the two polymers. And, the adsorption experiment results showed that the addition of PBMA contributed to the enhancing adsorptive properties of blend fibers, which lays the foundation for further studying PAN/PBMA blend fibers with adsorptive function. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010