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Cellulose nanocrystals as green fillers to improve crystallization and hydrophilic property of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

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Progress in Natural Science:Materials International 2011年第6期21卷 478-484页

作者： Hou-yong YU~(1,2),Zong-yi QIN~1,Zhe ZHOU~2 1.State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University,Shanghai 201620,China 2.College of Material Science and Engineering,Donghua University,Shanghai 201620,China State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Donghua University Shanghai 201620 China College of Material Science and Engineering Donghua University Shanghai 201620 China

The green nanocomposites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) with various cellulose nanocrystals (CNCs) contents were prepared by solution casting *** effects of CNCs on the crystallization behavior,spherulitic morphology,crystal structure and hydrophilic property of PHBV were studied by differential scanning calorimeter(DSC),polarized optical microscope(POM),wide-angle X-ray diffraction(WAXD) and static water contact angle *** is found that the CNCs act as an effective nucleation agent for crystallization of PHBV,inducing an increase in the melt crystallization temperature of the nanocomposites.A study of the non-isothermal crystallization kinetics further illustrated that overall crystallization rate of PHBV in the nanocomposites was faster than that of neat PHBV,but exhibited a decrease in the crystallinity and the spherulite size of PHBV. Furthermore,the contact angle decreased from 60.1°for neat PHBV to 32.5°for the nanocomposites with 10%CNCs(mass fraction).

关键词： nanocomposites poly(3-hydroxybutyrate-co-3-hydroxyvalerate) cellulose nanocrystals crystallization behavior hydrophilic property

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IMPROVING hydrophilicITY AND PROTEIN ANTIFOULING OF ELECTROSPUN POLY(VINYLIDENEFLUORIDE-HEXAFLUOROPROPYLENE) NANOFIBER MEMBRANES

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Chinese Journal of Polymer Science 2010年第5期28卷 705-713页

作者：李新松 Biomaterials and Drug Delivery Laboratories School of Chemistry and Chemical EngineeringSoutheast University

Poly（vinylidenefluoride-hexafluoropropylene）（PVDF-HFP） nanofiber membranes with improved hydrophilicity and protein fouling resistance via surface graft copolymerization of hydrophilic monomers were prepared. The surface modification involves atmospheric pressure glow discharge plasma （APGDP） pretreatment followed by graft copolymerization of poly（ethylene glycol） methyl ether methacrylate （PEGMA）. The success of the graft modification with PEGMA on the PVDF-HFP fibrous membrane is ascertained by X-ray photoelectron spectroscopy （XPS） and attenuated total reflectance Fourier transform infrared measurements （ATR-FTIR）. The hydrophilic property of the nanofiber membranes is assessed by water contact angle measurements. The results show that the PEGMA grafted PVDF-HFP nanofiber membrane has a water contact angle of 0° compared with the pristine value of 132°. The protein adsorption was effectively reduced after PEGMA grafting on the PVDF-HFP nanofiber membrane surface. The PEGMA polymer grafting density on the PVDF-HFP membrane surface is measured by the gravimetric method, and the filtration performance is characterized by the measurement of water flux. The results indicate that the water flux of the grafted PVDF-HFP fibrous membrane increases significantly with the increase of the PEGMA grafting density.

关键词： Poly(vinylidenefluoride-hexafluoropropylene) Nanofiber membrane Graft polymerization hydrophilic property Protein fouling resistance.

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Controllable synthesis of core-shell Co@C@SiO2 catalysts for enhancing product selectivity in Fischer-Tropsch synthesis by tuning the mass transfer resistance

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Journal of Energy Chemistry 2020年第12期29卷 199-206页

作者： Yao Chen Xin Li Liya Dai Mehar U Nisa Chengchao Liu Shuai Lv Jing Lv Zhenhua Li Key Lab for Green Chemical Technology of Ministry of Education School of Chemical Engineering and TechnologyCollaborative Innovation Center of Chemical Science and Engineering(Tianjin)Tianjin UniversityTianjin 300072China Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission&Ministry of Education College of Chemistry and Materials ScienceSouth-Central University for NationalitiesWuhan 430074HubeiChina

Fischer-Tropsch synthesis(FTS) is the key step in converting syngas into clean fuels. Traditional supported catalysts for FTS are problematic because the active metal crystalline size is positively related to metal loading. Therefore, increasing active metal loading may reduce the cobalt time yield(CTY) since a high CTY is usually obtained when the Co size is 8 nm. Here, a ZIF-67(Zeolitic imidazolate framework-67) with a MOF(Metal organic framework) structure is used as a precursor to prepare the Co@C catalyst with not only high cobalt loading(55.6 wt%) but also with a small cobalt crystal size(as small as 8.6 nm). Coreshell Co@C@SiO2-X catalysts with different SiO2 shell thicknesses were successfully prepared by coating different amounts of TEOS on the outer surface of Co@C to modify product selectivity. Compared with40 wt% Co/SiO2 catalyst, core-shell Co@C@SiO2-X catalysts exhibited improved FTS performance. Furthermore, different gaseous hourly space velocities(GHSVs) were used to obtain CO conversion at similar levels to compare CTY and the turnover frequency(TOF). Among the catalysts, the Co@C@SiO2-1 catalyst, with its better mass transfer ability and suitable hydrophilic property, presented the highest TOF(9.75 × 10-3 s-1) and lowest CH4 selectivity(9.75%). In addition, heavy hydrocarbons were effectively suppressed with the increase in shell thickness due to the increased mass transfer resistance.

关键词： Fischer-Tropsch synthesis ZIF-67 Product selectivity Core-shell catalyst hydrophilic property

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