Enhancement of Adhesive Strength of Ultrahigh Molecular Weight Polyethylene Fibers Prepared by Polar Polymer Implantation

A new technique was proposed to enhance the adhesive strength of ultrahigh molecular weight polyethylene （UHMWPE） fibers. Polar polymer was implanted into UHMWE gel fibers during extracting process and can then be trapped on the surface of the fibers after subsequent ultra-drawing. The physical and chemical changes in the fiber structure were examined with scanning electron microscopy （SEM） and Fourier transform infrared （FTIR） spectroscopy. The mechanical and interfacial adhesion properties of UHMWPE fibers were investigated with tensile testing. The results showed that there were polar groups on the smface of pretreated UHMWPE fiber. The interracial shear strength of UHMWPE fibers with epoxy resin was greatly improved without sacrificing the excellent mechanical p~perties of fibers. After pretreated with ethylene/vinyl acetate copolymer （EVA）, the shear strength of the interface between fiber and epoxy resin increased from 1.06 to 2.49 MPa, while the integrated mechanical properties d the pretreated UHMWPE fibers were still optimal.     

超高相对分子质量聚乙烯纤维的表面粘结性能研究

在萃取阶段用表面改性剂溶液对超高相对分子质量聚乙烯（UHMWPE）冻胶纤维进行表面处理，然后经过多级热拉伸制得改性纤维。对萃取液进行了紫外吸光度分析，并对改性前后纤维的表面化学结构、力学性能和表面粘结性能进行了比较。结果表明；经表面处理的纤维表面引入许多极性基团，纤维粘结强度随拉伸倍数增加而提高，纤维粘结性能得到较大改善；表面处理对纤维的力学性能影响不大。其中EVA的改性效果最为明显，3级拉伸后纤维的粘结强度提高了100％．     

Electrospinning preparation and characterization of polyoxometalate fibers

Polyoxometalates (POMs), a kind of inorganic metaloxygen clusters, can keep their definite structures eitherin solution or in solid. More and more attentions havebeen paid to the POMs due to their variety in structureand modifiability as well as adjustmen…     

Fabrication and character ization of electrospun TiO2/CuS micro–nano-scaled composite fibers

A process to fabricate a kind of novel micro–nano scaled TiO2/CuS composite fibers by electrospinning technique and chemical precipitation method was developed in the present study. The microstructures and photoelectronic properties of the fibers were characterize d using SEM, FT-IR, UV–vis and fluorescence spectroscopy. The results revealed that the TiO2 portion in the composite fibers was a mixture rutile and anatase phases while TiO2 and CuS had been fully composite. The fibers had smooth surface with a diameter of 50–300 nm. Comparing with pure TiO2 fiber, the TiO2/CuS micro–nano-scaled composite fibers exhibited a strong absorption in the visible light region and the efficiency of photo-induced charge separation were enhanced. This composite system is of widely potential applications in the areas such as solar cells, supercapacity, photocatalysis, etc.     

Fabrication and properties of aluminum silicate fibrous materials with <Emphasis Type="Italic">in situ</Emphasis> synthesized K<Subscript>2</Subscript>Ti<Subscript>6</Subscript>O<Subscript>13</Subscript> whiskers

To improve their mechanical and thermal insulation properties, aluminum silicate fibrous materials with in situ synthesized K₂Ti₆O₁₃ whiskers were prepared by firing a mixture of short aluminum silicate fibers and gel powders obtained from a sol-gel process. During the preparation process, the fiber surface was coated with K₂Ti₆O₁₃ whiskers after the fibers were subjected to a heat treatment carried out at various temperatures. The effects of process parameters on the microstructure, compressive strength, and thermal conductivity were analyzed systematically. The results show that higher treatment temperatures and longer treatment durations promoted the development of K₂Ti₆O₁₃ whiskers on the surface of aluminum silicate fibers; in addition, the intersection structure between whiskers modulated the morphology and volume of the multi-aperture structure among fibers, substantially increasing the fibers' compressive strength and reducing their heat conduction and convective heat transfer at high temperatures.     

A novel graphite/phenolic resin bipolar plate modified by doping carbon fibers for the application of proton exchange membrane fuel cells

In this study, the carbon fibers treated by three methods were selected as a reinforcement to investigate the influence on the properties of composite bipolar plates. The properties and microstructure of the composite bipolar plate were characterized by the four-point probe, universal test machine, contact angle tester and scanning electron microscopy. The optimum treatment methods and the fiber content were analysed. The results showed that the carbon fibers treated by Fenton reagent for 2 ​h exhibited the best performance, which could improve the electrical conductivity and the flexural strength for composite bipolar plate. Besides, the optimal content content of carbon fibers treated by Fenton reagent was 4%. The maximum power density of the PEMFC with the composite bipolar plates could reach 662.75 ​mW ​cm⁻² in H₂-air conditions. Therefore, the phenolic resin/graphite composite bipolar plate modified by doping carbon fibers was a promising candidate for bipolar plate materials for PEMFC.     

UHMWPE冻胶纤维超倍拉伸性能研究

超倍拉伸是制备高强高模聚乙烯纤维的有效途径。研究了萃取、干燥工艺及拉伸速度、浸度等对超高相对分子质量聚乙烯冻胶纤维拉伸性能的影响。结果表明：聚乙烯冻股纤维最大拉伸倍数随萃取除油率的增加而增加；纤维萃取后干燥时有一最佳干燥温度，为25℃左右；随冻胶纤维萃取干燥收缩率的增大，纤维结晶度增加，拉伸性能变差；聚乙烯纤维的拉伸速度不能太高，拉伸温度存在一最佳范围。     

纳米粒子均匀分散超高相对分子质量聚乙烯冻胶纤维的制备

将纳米粒子均匀分散于萃取荆中，在萃取阶段将其加入到超高相对分子质量聚乙烯(UHMWPE)纤维中，对其进行改性。通过表面扫描电镜(SEM)，萃取液粘度和冻胶纤维萃取除油率的测定，研究了纳米粒子在UHMWPE冻胶纤维中的分散情况及纳米粒子的加入对冻胶纤维萃取过程的影响。结果表明：在萃取过程中，纳米粒子可以扩散进入冻胶纤维中并可在冻胶纤维中达到纳米级均匀分散；纳米粒子的加入使萃取剂粘度增加，对UHMWPE冻胶纤维的萃取速率变慢。     

纳米SiO2修饰玻纤表面对玻纤/聚丙烯复合材料界面性能的影响

借助纳米颗粒的高比表面积特性,将纳米二氧化硅通过化学接枝方法修饰玻璃纤维表面,制备玻璃纤维/聚丙烯（PP）热塑复合材料。通过SEM表征纳米二氧化硅在玻璃纤维表面的分布形态,结果表明纳米颗粒在纤维表面分散良好;通过界面剪切强度测试（IFSS）和界面断裂韧性测试（G_ⅡC）表征复合材料界面的静态力学性能,结果显示材料的界面剪切强度与界面断裂韧性同时获得了较大的提升;动态热机械分析测试（DMA）的结果表明复合材料在动态测试下的综合界面结合性能均得到较大的提升。     

Thermal Properties of Crosslinking Modified Ultrahigh Molecular Weight Polyethylene Fibers by Ultra-Violet Irradiation

By means of ultra-violet(UV)irradiation with photoini-tiator and multifunctional crosslinking agent,thecrosslinking modification of ultrahigh molecular weightpolyethylene(UHMWPE)fibers prepared by gel-spin-ning was carried out.Thermal properties of fiber sampleswere examined using differential scanning calorimetry(DSC),thermomechanical analysis(TMA)apparatusand a manual device.The results indicated that the opti-mal irradiation energy is 250-400 mJ/cm~2,heat-andcreep-resistant behaviors of modified fibers have beenimproved.     

利用蚕丝制作的微米光器件的研究

利用Na2CO3水溶液将蚕茧去除丝胶得到直径为5～15μm的生物纤维,采用扫描电镜(SEM)和透射电镜(TEM)观察了其形貌特征。通过倏逝波耦合的方法,利用SiO2微纳光锥将波长为671 nm的红光、532 nm的绿光、473 nm的蓝光分别耦合进入微米蚕丝生物光纤,分析了其导光特性,测量了光在蚕丝纤维中的传输损耗。制作了2×2、3×1、1×4、环形等光子结构。实验证明蚕丝微米生物光纤具有良好的柔韧性和表面光滑度,其中波长为532 nm的绿光在直径为9.0μm的蚕丝纤维中传输时的损耗为0.78 dB.mm-1。     

Thermal behavior of zirconia-dop ed mullite gel fibers

The zirconia-doped mullite gel fibers were prepared via a sol-gel method.The thermal behaviors of the gel fibers during pyrolysis were investigated by means of thermal gravitydifferential scanning calo...     

纳米二氧化硅修饰玻纤表面对玻纤增强聚丙烯复合材料性能的影响

基于纳米颗粒比表面积高的特性，将超声震荡分散后的纳米SiO₂通过化学接枝方法修饰玻璃纤维表面制备玻璃纤维/聚丙烯热塑性复合材料。通过扫描电子显微镜（SEM）表征纳米SiO₂在玻纤表面的分布状态及其与纤维树脂的结合情况，结果表明纳米颗粒在纤维表面分布状况良好，纤维与树脂能较为紧密地结合。通过动、静态力学测试表征复合材料的界面结合情况及整体力学性能，结果表明复合材料在动态热机械分析（DMA）测试下具备良好的综合界面性能；与空白组对比，复合材料的层间剪切强度最高提升约86%，拉伸强度最高提升约300%，弯曲强度最高提升约94%。     

Characterization of γ-Fe2O3 nanoparticles prepared by transfor- mation of α-FeOOH

γ-Fe2O3 nanoparticles were successfully synthesized by a chemically induced transformation of α-FeOOH.In this method,the precursor(α-FeOOH)was prepared by chemical precipitation,and then treated with a mixed FeCl2/NaOH solution to produce the nanoparticles.X-ray diffraction indicated that when the precursor was treated with FeCl2(0.22 mol/L)and NaOH(0.19 mol/L),pure γ-Fe2O3 nanoparticles were obtained.However,when the concentration of FeCl2 was<0.22 mol/L or the concentration of NaOH was<0.19 mol/L,α-FeOOH and γ-Fe2O3 phases co-existed in the nanoparticles.Transmission electron microscopy observations showed that in the samples with co-existing phases,the nanoparticles did not have identical morphologies.The pure γ-Fe2O3 nanoparticles were polygonal rather than spherical.The volume ratio of α-FeOOH and γ-Fe2O3 was estimated for the two-phase samples from magnetization data obtained from a vibrating sample magnetometer.This chemically induced transformation is novel,and could provide an effective route for the synthesis of other metal oxide nanocrystallites.     

Influence of sulfides on the tribological properties of composites produced by pulse electric current sintering

Self-lubricating Al₂O₃-15wt% ZrO₂ composites with sulfides, such as molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂) serving as solid lubricants, were fabricated by using the pulse electric current sintering (PECS) technique. The coefficient of friction (COF) of the Al₂O₃-15wt% ZrO₂ composite without/with sulfides was in the range of 0.37–0.48 and 0.27–0.49, respectively. As the amount of sulfides increased, the COF and the wear rate decreased. The reduction in COF and wear rate of the sulfide-containing composite is caused by a reduction in shear stresses between the specimen and the tribological medium due to the formation of a lubricating film resulting from the lamellar structure of sulfides located on the worn surface.     

Surface Treatment of UHMWPE Fibers for Adhesion Promotion in Epoxy Polymers

Surface of Ultra-high molecular weight polyethylene （UHMWPE） fiber were treated by chromic acid chemical etching, pyrrole chemical vapour phase deposition and the complex of these two methods, respectively. The change of surface properties and structure of fibers were discussed by Fiour Transform Infrared Spectroscope （FTIR）, Dynamic Mechanical Analysis （DMA） and Scanning Electron Microscope （SEM）. The results show that some new oxygenous groups could be found on surface of UHMWPE fiber after chromic acid chemical etching, which enhanced intemolecular interaction with polypyrrcle. The adhesion of the fiber and resin natrix increased after pyrrole chemical vapour deposition. When chromic acid etching combined with pyrrole chemical vapor deposition, the treated fiber not only has the same properties as original fiber bat also outstanding adhesion to epoxy resin matrix, and its composites have better mechanic properties shear strength）, resulting from intemolecular interaction treated fiber and polypyrrole.     

ZnO及其掺杂纳米粒子的反相微乳液法合成及表征

 分别以OP/正庚烷/正己醇/水溶液和吐温60/溴代十六烷基吡啶/二甲苯/正戊醇/水溶液反相微乳液体系,合成了ZnO及ZnO-Cr₂O₃,ZnO-Cr₂O₃-NiO,ZnO-Cr₂O₃-NiO-MnO掺杂纳米粒子.研究了前驱物、反应物浓度和后处理对粒子制备和粒径的影响.结果表明:所给微乳液体系适合ZnO及其掺杂纳米粒子的制备;通过选择反应途径及控制反应物浓度可实现对粒径的控制;ZnO纳米粒子的粒径为10～200nm,二元、三元、四元掺杂型纳米粒子的粒径均约为20nm.     

The strain ampli tude-controlled cyclic fatigue behavior of Al2O3 fiber reinforced Al–Si alloy composite at elevated temperatures

The strain amplitude-controlled fatigue characteristics of an Al–Si casting alloy and itscomposite reinforced with 17 vol% Al₂O₃ fibers (Al–Si/Al₂O₃) are studied at three different temperatures. Both the alloy and the composite showed different degrees of cyclic softening at elevated temperatures. Increasing the temperature, fatigue damage of either the alloy or the composite occurred with varying mode from brittle fracture of silicon particles to their separation from the aluminum matrix. This is explained by the different thermal expansion coefficients of silicon particles and the aluminum matrix. The reinforcement Al₂O₃ fibers in the composite showed a similar damage behavior with those silicon particles despite temperature variation     

Promising psyllium-based composite containing TiO2 nanoparticles as aspirin-carrier matrix

Composite nanomaterials represent a new trend in the biomedical field. Coupling inorganic/organic constituents with non-toxicity/biocompatibility properties leads to develop the new systems having special characteristics that can be used in various bio-applications. This paper describes the preparation and characterization of psyllium-based composites containing TiO2 nanoparticles in order to develop new therapeutic strategies for aspirin drug delivery. The structural characteristics of obtained materials were investigated by FTIR spectroscopy. The UV–vis spectrophotometric analysis was performed to evaluate the aspirin release behavior under different pH conditions at 37 1C. Combining psyllium(as an excellent source of fiber) with TiO2 inorganic unit(as vehicle of aspirin) it was found that polymeric-TiO2networks have promising potential for controlled aspirin release as therapeutic agent.