Papers by Author: Chun Yi Liu

Abstract: The interaction between polyacrylonitrile (PAN) and various plasticizer at different temperature was discussed by infrared analysis. At the room temperature, the interaction between nitrile groups of polymer is so strong that the conventional plasticizer propylene carbonate (PC) or new-type plasticizer ionic liquid can’t have interaction with nitrile groups. However, the interaction between nitrile groups weakens at higher temperature, i.e. 160°C, and the interaction between the nitrile groups and IL is formed, which is maintained when natural cooling to 90°C. The interaction between the nitrile groups and IL weakens again when natural cooling to room temperature, it may be attributed to the interaction between IL and water is stronger than that of IL and PAN.

Abstract: Polyacrylonitrile (PAN) membranes were prepared via thermally induced phase separation (TIPS) process using polyethylene glycol (PEG) as plasticizing agent and polyvinyl pyrrolidone (PVP) as porogen, which presented high strength, i.e. 6MPa. A systematic study was carried out to investigate the effect of PVP content, PAN concentration and cooling conditions on the pore shape, pore size, water flux and mechanical properties of the membranes, which were characterized by scanning electron microscope, filtration measurement and tensile test. PAN membranes with uniformly distributed pores were fabricated by adjusting the mixed diluent composition. Results of filtration confirm that water flux of PAN membranes mainly depends on the pore structure. Moreover, while PVP content is increased, water flux first increases and then declines, and tensile strength and elongation at break first declines and then increases. In conclusion, the successful application of TIPS provides a new route to the structure modulation and performance enhancement of PAN membranes.

Abstract: Poly (vinylidene fluoride) (PVDF) hybrid membranes reinforced by hydrophilic nanoSiO₂ particles were fabricated from PVDF/N-dimethylacetamide (DMAc)/γ-butyrolactone (γ-BL) system via thermally induced phase separation (TIPS) process. Surface and cross-sectional morphology of membranes were characterized by scanning electron microscope (SEM). The properties such as permeability, mechanical performances and antifouling property were also determined. The results showed that the pore size of membrane surface became smaller, while cross-sectional morphology was changed from bicontinuous structure to cell structure, the pore size became larger and majorities of closed pores became open with the addition of hydrophilic nanoSiO₂ particles in the system. Compared with pure membrane, pure water flux of hybrid membrane increased by 30.3%, i.e. from 290 to 378 L/(m²·h·0.1MPa), antifouling property increased from 63.1% to 80.2%. Meanwhile, tensile strength and elongation at break increased by 70.6% and124%, respectively.

Abstract: Plasticized polyacrylonitrile(PAN) fibers have been chemically impregnated with aqueous solution of KMnO₄ under varying conditions of temperature and time. The effect of modification conditions on the chemical structure and the mechanical properties of precursor fibers are characterized by wide-angle X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscope. The experimental results show that KMnO₄ can be used not only as catalyst for cyclization reaction, but also as plasticizer. The chemical modification between KMnO₄ and PAN can not occur below70°C, the most suitable condition for modification is performed at 80°C for 5 min.

Abstract: A new membrane carrier was presented to immobilize zero-valent iron nanoparticles (ZVI NPs) for the removal of contaminants in water. The modified PAN-based oxidized membrane was prepared through acid treating method and used as a nanoreactor to chelate Fe (III) ions for the reductive formation of highly reactive ZVI NPs. The ZVI NP immobilized membrane system is stable and effectively degrades trichloroethylene (TCE). These results suggest that PAN-based oxidized membrane containing ZVI NPs exhibits the good properties and significant potential for environmental applications.

Abstract: Polyethersulfone (PES) flat sheet membranes were prepared via phase inversion induced by immersion precipitation from a novel lower critical solution temperature (LCST) system containing PES, 1-butanol and N, N-dimethylacetamide. And the effect of coagulation bath temperature on the properties and structure of PES membranes were investigated. The results show that the pure water flux increases and the tensile strength decreases as the coagulation temperature increases form 20°C to 50°C. Besides, the SEM images shows that all of the membranes prepared from a LCST system at different CBT own sponge-like structures.