Papers by Author: Zhen Liu

Abstract: Poly(vinylidene fluoride) (PVDF)/1-butyl-2,3-dimethylimidazolium Tetrafluoroborate ([BMMIm][BF4]) flat sheet membranes were made via thermally induced phase separation (TIPS) melt technology, and [BMMIm][BF4]) was used as a diluent. The prepared membranes were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) and etc. Furthermore, [BMMIm][BF4] as a liquid-diluent was effectively recovered by vacuum distillation. In conclusion, this work may provide a green and sustainable preparation method to produce PVDF membranes via TIPS.

Abstract: Polysulfone (PSF) hollow fiber ultrafiltration membranes were successfully prepared by dry-wet spinning technology. Dimethylacetamide (DMAC) was used as a solvent, water was used as bore liquid and coagulation bath, polyvinylpyrrolidone (PVP) was used as polymeric additive. The effects of spinning conditions on membrane structures and properties were investigated in present study. The results indicated that with the increase of PVP concentration, pure water flux increased and developed finger-like pores were formed. High coagulation bath temperature restricted pure water flux, 30°C was the best for the preparation of high-performance ultrafiltration membranes. When the air length was 11cm, the membrane comprehensive performance was the best.

Abstract: The surface of polypropylene hollow fiber membrane was modified with N,N’-methylene-bisac-rylamide (MBA) by the UV-irradiation, with the benzophenone (BP) as the light initiator. Fourier transform infrared spectrometer (FT-IR) was utilized to characterize copolymer composition. Field emission scanning electron microscopy (FE-SEM) was utilized to observe the fiber surface and section. Results showed that MBA was grafted on the surface of membrane. The influence was researched by changing the concentration of BP, MBA and irradiated time. Results showed that the grafting rate grew rapidly and then declined as the increase the BP concentration. The grafting rate increased at first as the MBA concentration increased, but decreased after the maximum. The grafting rate firstly increased slowly and then increased sharply with the irradiated time extended.

Abstract: Lamellas important for micropores were well formed during extrusion and annealing process in melt-spinning and stretching method. This unusual crystalline structure and its changing during annealing and stretching process were well studied in term of lamellar size, lamellar crystallite orientation, degree of lamellar and observation of morphology. Lamellar and microfibril model was accepted as mechanism of making micropore for this process. Gas permeability and porosity testing experimental were used to characterize membrane properties.

Abstract: The Polysulfone Flat ultrafiltration membranes were prepared with dimethylacetamide (DMAc) as solvent and polyvinypyrrolidone (PVP) as pore forming additive. Performance of PSF membrane such as pure water flux, albumin egg rejection were investigated. In addition, the same investigations were conducted with different coagulation bath temperature and evaporation time. The results show that there were a maximum of pure water flux and a minimum of the retention of Albumin when PVP content reach 14%.

Abstract: A set of polyether-urethane block copolymers were prepared that poly (tetramethylene oxide) PTMO was regarded as soft segment, 4,4'-methylenebis(phenyl isocyanate)(MDI) and m-diphenylamine (MDM) was regarded as hard segment in this article. The microphase separation of polyether-urethane block copolymer was investigated by using infrared spectroscopy(FTIR), differential scanning calorimetry(DSC), small-angle X-ray scattering(SAXS),there obtained that there are two phases structure in polyether-urethane block copolymers and degree of phase separation decrease with increasing hard segment weight content.

Abstract: To promote a technological use of Mg alloy castings on motorbike, a technical routine for material substitution was demonstratively presented with engine crankshaft case and motorbike wheels. It was shown that, subjected to failure analysis, comparative FEM analyses, structural redesign, numerical optimization of casting process and strict tests of prototypes, the service performance of the Mg castings can be ensured, in addition to the performance improvement stemming from the advantageous properties of Mg alloys.