聚偏氟乙烯/聚丙烯腈共混超滤膜的研究

讨论了聚偏氟乙烯 /聚丙烯腈共混体系的相容性 ,对PVDF/PAN共混体系的相容性进行了理论分析和相容性预测 ,并通过实验对相容性进行了评价 .结果表明 ,PVDF/PAN属部分共混体系 .利用该体系可制得性能优良的PVDF/PAN共混超滤膜 .讨论了铸膜液的组成、制膜条件对膜性能的影响 ,并对膜性能和膜结构进行了测试 ,得到了较好的结果 .

多硫化钠——溴化钠氧化还原液流电池研究

在全电池中用稳态方法研究了不同电极材料对电池正负极电化学反应极化行为的影响。以聚丙腈碳毡为正极材料,泡沫镍为负极材料,4mol/LNaBr、1.3mol/LNa2S4为正、负极电解液,测定了(28±1)℃时电池的库仑效率、电压效率、能量效率及电池的能量密度随充放电电流密度的变化规律,分析了大电流密度下电池电压效率下降的原因。以聚丙腈碳毡及泡沫镍为正负极材料所组成的电池能量效率约71%,能量密度约66.4mW/cm2(50mA/cm2充放电),电池的欧姆内阻压降是大电流密度下电池电压效率下降的主要原因。

KOH二次活化制备富含中孔的PAN-ACF

以水蒸汽活化的聚丙腈基活性炭纤维 (PAN ACF)为原料 ,研究了KOH二次活化对PAN ACF纳米孔隙结构发展过程的影响。以氮吸附等温线为基础 ,根据微孔填充理论 ,采用αs plot和DFT等方法研究了二次活化PAN ACF的纳米微结构。结果表明 :在实验考察范围内 ,经过二次活化后PAN ACF的比表面积和孔容积增加 ,尤其中孔容积增加显著 ,约占总孔容积的 5 0 % 。

PMMA/α-MSAN共混体系长时弛豫区域的时温叠加失效与相分离的关系

通过考察聚甲基丙烯酸甲酯（ＰＭＭＡ）／聚（α－甲基苯乙烯丙烯腈）（α－ＭＳＡＮ）共混体系动态粘弹函数的时温叠加，发现在终端区域时温叠加失效与其相分离有关．相分离使得终端区域的动态储能模量Ｇ′（或动态损耗模量Ｇ″）与频率的关系［ｌｇＧ′（ｌｇＧ″）～ｌｇω］明显偏离经典粘弹模型．随组成的改变，时温叠加的失效呈现温度依赖性，其“失效温度”（Ｔｄ）可很好地表征ＬＣＳＴ类共混物的相分离，而且在用其表征相分离时。

Adsorption characteristics of carbon tetrachloride from aqueous solution onto polyacrylonitrile-based activated carbon fiber

The isotherm,mechanism and kinetics of carbon tetrachloride(CT) adsorption by polyacrylonitrile-based activated carbon fiber(PAN-ACF) were investigated in batch reactors and a continuous flow reactor,and the regeneration of PAN-ACF was also studied.Freundlich and Dubinin-Radushkevich(D-R) adsorption equations can well describe the adsorption isotherm.CT is mainly adsorbed on the exterior surface of PAN-ACF with low boundary layer effect and rate-controlling step of intra-particle diffusion.The adsorption dynamics in the batch reactor well fits with the pseudo-first-order model,and the breakthrough curves in the continuous flow reactor can be well described by the Yoon-Nelson model.The ACF can be recycled through thermal regeneration,whereas the adsorption capacity decreases from 7.87 to 4.98 mg/g after the fourth regeneration.78%-94%of CT can be removed from the wastewater of a fluorine chemical plant on a pilot scale,which confirms the efficacy of ACF under industrial conditions.The results indicate that PAN-ACF is applicable to CT removal from wastewater.

Catalytic graphitization of Mo-B-doped polyacrylonitrile(PAN)-based carbon fibers

A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly dispersed Mo-B sol.The as-treated carbon fibers were then graphitized at 2 400 ℃ for 2 h.The structural changes were characterized by X-ray diffractometry(XRD),Raman spectroscopy,scanning electron microscopy(SEM) and high-resolution transmission electronic microscopy(HRTEM).The results show that much better graphitization can be achieved in the presence of Mo-B,with an interlayer spacing(d002) of 0.335 8 nm and a crystalline size(Lc) of 28 nm.

Catalytic graphitization of polyacrylonitrile(PAN)-based carbon fibers with Fe-Cr_2O_3 composite coating

The process of electrodepositing Fe-Cr2O3 composite coating on polyacrylonitrile （PAN）-based carbon fibers and its catalytic graphitization were studied. Carbon fibers with and without electrodeposited Fe-Cr2O3 composite coating were heat treated at different temperatures and the structural changes were characterized by XRD, Raman spectroscopy and SEM. The results indicate that Fe-Cr2O3 composite coating exhibits a significant catalytic effect on graphitization of carbon fibers at low temperatures. When the Fe-Cr2O3-coated carbon fibers were heat treated at 1 300℃ the interlayer spacing （doo2） and ratio of relative peak area （AD/AG） reach 3.364/k and 0.34, respectively. Whereas, the extent of graphitization of pristine carbon fibers is comparatively low even after heat treatment at 2 800℃ and the values of doo2 and AD/AG are 3.414 A and 0.68, respectively. The extent of graphitization of carbon fibers increases not only with the increase of the catalyst gross but also the Cr2O3 content in Fe-Cr2O3 coating. The catalytic effect of Fe-Cr2O3 composite coating accords with the dissolution-precipitation mechanism.

Phase Partition of Acrylonitrile(AN)in Vinylidene Chloride(VDC)/Water System and Its Effect on VDC-AN Copolymer Composition

Phase partition of acrylonitrile in the vinylidene chloride/water system at different temperature and under pressure was studied. A calculation method for average VDC-AN copolymer composition with AN phase partition considered was proposed. The calculated results are in good agreement with the experimental data nearly the entire conversion range. VDC-AN copolymer with narrower composition distribution can be prepared in the suspension process and interpreted with dynamic equilibrium of AN between the oil and water phases continuously.

Structure Analysis of Polyacrylonitrile Polymerized in Ionic Liquids

Polyacrylonitriles （PANs） ware synthesized both by atom transfer radical polymerization （ATRP） anti free radical polymerization in ionic liquid 1 - buty - 3 - methylimidazolium chloride （[bmim]Cl）. [bmim]Cl demonstrates to be a preferable solvent for ATRP of acrylonitrile （AN）. The polymerization maintains the usual advantages of ATRP with molecular weight agrees well with theoretical value and low polydispersity （PDI = 1.15）. It is also shown the higher conversion and lower molecular weight dispersion in ionic liquid than in dimethylformamide （DMF）. From FTIR and NMR analysis, it is confirmed that the chemical structures of PANs synthesized in [bmim]Cl were identical with that obtained in DMF. In atom transfer radical polymerization, the methine and cyan carbon atoms in isotactic configuration for PAN produced in [bmim] Cl have a configuration consisting of about 55.5% isotactic diads. It is higher than that obtained in DMF which is 52.2%. So, ionic liquid has effect on the stereostructure of PANs. Further analysis of ^13C NMR spectra indicated that the isotacticity of PAN synthesized by free radical polymerization was lower than that of PAN prepared by ATRP, although both of them were random in stereoregularity. Besides the pentad tacticities of PANs also suggested that the sequence distributions of them all obey Bernoulli statistics.

Rheological Properties of Soy Protein Isolate and Polyurethane in the PAN/DMSO Solution

The rheological properties of soy protein isolate （SPI） and polyurethane （PU） in the PAN/DMSO solution were investigated in this study. The results showed that all these solutions possessed pseudo-plastic solution properties. There are opposite effects of SPI and PU in the PAN/DMSO solution. Their apparent viscosity, degree of non-Newtonian fluid, and extent of structuralization of blend system increase with the addition of SPI, whereas, all of these decrease with the addition of PU. Moreover, the theological properties of PAN/DMSO solution were affected when SPI and PU were added equally, and SPI presented more effect when the proportion of ingredient was less, and PU presented more effect when the proportion of ingredient was more.

Preparation of Mesoporous Carbons from Acrylonitrile-methyl Methacrylate Copolymer/Silica Nanocomposites Synthesized by in-situ Emulsion Polymerization

Acrylonitrile-methyl methacrylate （AN-MMA） copolymer/silica nanocomposites were synthesized by in-situ emulsion polymerization initiated by 2,2＇-azobis（2-amidinopropane） dihydrochloride absorbed onto colloidal silica particles, and the mesoporous carbon materials were prepared through carbonization of the obtained AN-MMA copolymer/silica nanocomposites, followed by HF etching. Thermogravimetric analysis of AN-MMAcopolymer/silica nanocomposltes snoweO mat me caroon ylelCl or copolymer was slgnuy oecreaseo as Silica parucle incorporated. N2 adsorption-desorption, scan electron microscopy （SEM） and transmission electron microscopy （TEM） were used to characterize the structure and morphology of the mesoporous carbon materials. Both SEM and

Study on the Properties of Microcapsulated Chlorocyclophosphazene Polypropylene Composites

Microcapsulated chlorocyclophosphazenes were synthesized,and then microcapsulated chlorocyclo- phosphazene/polypropylene(PP)composites were prepared.The results showed that microcapsulated chlorocyclo- phosphazene had good high thermal stability through thermogravimetric analysis(TGA).The flammability and mechanical properties of microcapsulated chlorocyclophosphazene/polypropylene composites were investigated by limiting oxygen index experiment,UL 94V flame retardancy test,cone calorimetry,tensile experiment,and impact test,respectively.It was shown that the microcapsulated chlorocyclophosphazene/PP composites had better tensile strength,impact strength,flame retardant properties and smoke suppress properties compared with chlorocyclo- phosphazene/PP composites.

Study on the Mechanical Properties of Carbon Nanotube/Polyacrylonitrile Composite Fibers

The method of preparing the multi-walled carbon nanotubes (MWNTs)-polyacrylonitriIe (PAN) composite fibers is described and the effects of draw ratio on the mechanical properties of CNT/PAN fibers have also been discussed. The results show that the degrees of MWNTs dispersion in the polymer matrix have much effect on the mechanical properties.

Catalytic graphitization of polyacrylonitrile-based carbon fibers coated with Prussian blue

Prussian blue(PB) was used as catalyst to improve the extent of graphitization of polyacrylonitrile(PAN)-based carbon fibers.PB was deposited on carbon fibers by anodic electrodeposition and the thickness of PB coating(PB content) was controlled by adjusting the electrodeposition time.PAN-based carbon fibers with PB coating were heat-treated and the extent of graphitization was measured by X-ray diffractometry and Raman spectroscopy.The results indicate that the extent of graphitization of PAN-based carbon fibers is enhanced in the presence of the coating.When the PB-coated carbon fibers were heat-treated at 1 900 ℃,interlayer spacing(d002) and crystallite size(Lc) reach 0.336 8 and 21.2 nm respectively.Contrarily,the values of d002 and Lc are 0.341 4 and 7.4 nm respectively when the bare carbon fibers were heat-treated at 2 800 ℃.Compared with the bare carbon fibers,PB can make the heat treatment temperature(HTT) drop more than 500 ℃ in order to reach the same extent of graphitization.Furthermore,the research results show that PB content also has a certain influence on the extent of graphitization at the same HTT.

Acrylonitrile-methyl Methacrylate Copolymer Films Containing Microencapsulated n-Octadecane

Acryionitrilv-methyi mcthacrylate copolymer was synthesized in aqueous solution by Redox. The copolymer was mixed with 10 - 40 wt% of microencapsulated n-octadecane （MieroPCMs） in water. Copolymer films containing Mi- eroPCMs were cast at room temperature in N, N- imethyiformamide solution. The copolymer of acrylonitrile-methyl methacrylate and the copolymer films containing MicroPC- Ms were characterized by using Fourier Transform Infrared Spectroscopy （FTIR）, Differential Scanning Calorimetry （DSC）, Thermosravimetrlc Analyzer （TG）, X-ray Diffraction （XRD） and Scanning Electron Microscopy （SEM）, etc. The mierocapsules in the films are evenly distributed in the copolymer matrix. The heat-absorbing temperatures and heat-evolving temperatures of the films are almost the same as that of the MieroPCMs, respectively, and fluctuate in a slight range. In addition, the enthalpy efficiency of MieroPCMs rises with the contents of MicroPCMs increasing. The crystallirdty of the film increases with the contents of MicroPOMs increasing.

The Effect of Casting Solvent on the Electrical Property of Polyaniline/Polyacrylonitrile

Blends of dodecylbenzene sulfonic acid doped polyaniline （PANI-DBSA） and polyacryionitrile （PAN） dissolved in either CHCh/DMF or CHCl3/DMSO mixture were solution cast. The conductivity of the blends with various compositions was measured and the doped ：xtent of PANI- DBSA in different casting solvent systems was studied. Solution blends prepared from CHCh/DMSO displayed higher conductivity than those obtained via CHCh/DMF. The dedoping reaction of PANI-DBSA in CHCl3/DMF identified by UV-Vis and FTIR analysis contributed to the lower conductivity of PANI-DBSA/PAN blend.

The Chain Structure of Ultrahigh Molecular Weight Polyacrylonitrile

The chemical composition, molecular weight and its distribution, the bonding structure and the regulation of ultrahigh molecular weight polyacrylonitrile （UHMW-PAN） prepared by aqueous suspension polymerization were determined by FIIR, viscometry, GPC, ^3H-NMR and ^13CNMR. The mechanical properties of the porous hollow fiber prepared by UHMW-PAN were discussed to provide a theoretical basis for the preparation of ideal precursors of the porous hollow oxidation fiber.

Effects of ion chemistry and mass on the electrical properties of ion implanted pyrolyzed polyacrylonitrile

This paper describes the conductivity modifications induced by heavy ion implantation in pyrolysis products obtained by thermal treatment of polyacrylonitrile （PAN） thin films at temperatures of 435℃ （PAN435） and 750℃ （PAN750） under vacuum. Ionic species having different chemical reactivities such as Kr, As, Cl. and F ions were utilized to allow interpretation of the conductivity＇ data either in terms of implantation induced molecular rearrangements or in terms of specific chemical doping effects. The temperature dependence of conductivity in the range between 25-3000C followed nearly a simple activation conduction relationship from which the temperature coefficients of resistivity （ct） were determined. In this temperature range, PAN750 provided the smallest α value compared with ion implanted PAN750 or with products obtained at the lower pyrolysis temperature. However. the corresponding lowest rate of conductivity change with temperatures （0.49%/℃） obtained in this study far exceeds the specification value required for thin film resistor applications （〈 0.1%/℃）.

Development of Urease Immobilization Using Poly（acrylonitrile）/Chitosan Composite Materials

PANCHI （poly（acrylonitrile）/chitosan） composite membranes were prepared. The chitosan layer was deposited on the surface as well as on the pore walls of the base membrane. This resulted in the reduction of the pore size of the membrane and in an increase of their hydrophilicity. The pore structure of poly（acrylonitrile） and PANCHI membranes were determined by SEM analyses It was found that the membrane coated with 1.0% chitosan shows the maximum reduced pore size. The amounts of the functional groups and the degree of hydrophilicity of PANCHI composite membranes were determined. Urease was covalently immobilized onto all kinds of PANCHI membranes using glutaraldehyde. Both the amount of bound protein and relative activity of immobilized urease were measured. The highest activity （92.96%） was measured for urease bound to PANCHI （1%） membranes. The basic characteristics of optimum conditions （pH and temperature）, heat inactivation and storage stability of immobilized urease were determined. Immobilization improved the thermal, pH and storage stability of the enzyme. The obtained results show that the poly（acrylonitrile）/chitosan composite materials are suitable for urease immobilization.

Thermosensitive Poly(N-isopropylacrylamide-co-acrylonitrile) Hydrogels with Rapid Response

Acrylonitrile (AN) was copolymerized with N-isopropylacrylamide (NIPA) to synthesize thermosensitive hy-drogels, and the on-off switch behavior of poly(NIPA-co-AN) hydrogels with different fraction of hydrophobic compo-nent (AN) was investigated. It is found that the lower critical solution temperature (LCST), the swelling ratio at certain temperature and the reswelling rate of poly(NIPA-co-AN) hydrogels decreased as AN unit fraction in copolymers in-creased. In order to improve the responsive rate of poly(NIPA-co-AN) hydrogels, they were further treated by surface crosslinking using N, N′-methylene bisacrylamide (BIS) as a crosslinking agent. The swelling and deswelling behaviors of these copolymers were compared with those of the untreated hydrogels. The results indicated that the responsive rate of poly(NIPA-co-AN) hydrogel was improved by surface crosslinking. The resulting hydrogels bearing cyano groups with fast response have potential applications in the field of drug-controlled release and immobilization of biomolecules.