铁氧体/碳化硅涂层复合材料的介电性能研究

在涤纶基布上进行铁氧体/碳化硅双层复合涂层整理,制备1.0mm涂层厚度的柔性纺织涂层复合材料。研究了铁氧体和碳化硅含量对复合材料介电性能的影响,并测试了该复合材料的力学性能。结果表明,该柔性涂层复合材料在低频范围内具备良好的介电性能,且具备一定的力学性能。     

聚吡咯涂层织物的介电性能研究

采用原位聚合法以棉机织物、尼龙为基布,以吡咯为单体,制备了具有良好介电性能的柔性聚吡咯涂层棉织物和聚吡咯涂层尼龙织物,探讨了掺杂剂种类、掺杂剂浓度对聚吡咯涂层棉织物、聚吡咯涂层尼龙织物介电性能和表面电阻的影响.结果表明,掺杂剂对聚吡咯复合材料的介电性能和表面电阻的影响较大.所制备的聚吡咯涂层棉织物、聚吡咯涂层尼龙织物均具备良好的介电性能和导电性,为最终开发出较为实用的多功能吸波复合材料奠定了基础.     

铁氧体/碳化硅/石墨三层涂层复合材料介电性能

选用柔性涤纶针织物为基材,以铁氧体、碳化硅和石墨分别作为底层、中层和表层吸波剂,在基材上进行三层复合涂层整理,制备不同厚度的复合材料。探讨了底层、中层、表层厚度对介电常数实部、虚部和损耗角正切的影响。结果表明:该复合材料在低频段具备良好的介电性能,涂层厚度对介电常数实部、虚部和损耗角正切影响较大;底层铁氧体涂层厚度为0.5mm,中层碳化硅涂层厚度为0.3mm,表层石墨涂层厚度为0.3mm时,铁氧体/碳化硅/石墨三层涂层复合材料的介电常数实部、虚部、损耗角正切最大。     

碳化硅/石墨涂层复合材料的介电性探讨

研究了碳化硅和石墨含量对碳化硅/石墨双层复合材料介电常数实部、虚部、损耗角正切的影响。鉴于该材料多用于工程领域,测试了该复合材料的弯曲、剪切、拉伸等力学性能。结果表明:在低频段,该材料介电性能良好,碳化硅含量、石墨含量均对涂层复合材料的实部、虚部和损耗角正切影响较大;当碳化硅含量为24%,石墨含量为60%时,涂层复合材料的介电常数实部、虚部最大,其极化和损耗能力最强。另外,该复合材料具备良好的力学性能,最大弯曲强力为48.3N,最大剪切强力为57.5N,最大拉伸强力为618N。     

滑石粉涂层复合材料的制备及其介电性能和电导率

以玻璃纤维膨体纱织物为基材,以环氧树脂E44为粘着剂,650低分子量聚酰胺为固化剂,以价格低廉、密度较小的滑石粉为吸波材料,制备了滑石粉涂层复合材料。重点探讨了滑石粉含量及涂层厚度对介电常数和电导率的影响。结果表明制备的滑石粉涂层复合材料具备良好的介电性能。在研究的频率范围内,滑石粉的含量、涂层厚度对复合材料的介电常数实部和虚部、损耗角正切值、电导率的实部和虚部影响较大。     

聚吡咯/聚酯纤维复合材料吸波性能的探讨

聚吡咯是含有π电子共扼体系的高聚物,经掺杂反应电导率发生变化,当其电导率处于半导体状态时,具有良好的吸波性能.本文采用原位聚合法以聚酯纤维为基布,以吡咯为单体,制备具有良好吸波性能的柔性聚吡咯/聚酯纤维复合材料.首先探讨了吡咯浓度,温度,时间对复合材料吸波性能和表面电阻的影响;其次研究了其外观形貌和强力.结果表明:制备的聚吡咯复合材料具有良好的吸波性能;在0~106Hz频率内,吡咯浓度0.8 mol/L实验组,介电常数的实部、虚部均最大;1.0 mol/L实验组的损耗角正切最大;吡咯浓度0.8 mol/L实验组表面电阻最小;室温实验组的介电常数实部、虚部、损耗角正切最大,且明显优于其他组.反应时间150 min实验组的各项介电性能都明显优于其他组,且其电阻最小,导电率最好.     

柔性聚吡咯/尼龙复合材料介电性能的研究

以尼龙为基布,吡咯为单体,采用原位聚合法制备具有良好介电性能的柔性聚吡咯/尼龙复合材料。首先探讨了吡咯浓度、反应温度、反应时间对复合材料介电常数实部、虚部、损耗角正切、表面电阻的影响;其次研究了其微观形貌。结果表明:吡咯浓度、反应温度、反应时间对聚吡咯复合材料介电常数实部、虚部、损耗角正切、表面电阻影响较大;制备的聚吡咯复合材料具备良好的介电性能和导电性。     

双酚A型二氰酸酯树脂浸渍GC／PTFE透波复合材料的性能

采用双酚A型二氰酸酯(BADCy)树脂热融法对玻璃布(GC)/聚四氟乙烯(PTFE)复合材料进行浸渍以改善GC/PTFE透波复合材料的力学性能,研究了BADCy树脂的浸渍工艺、GC/PTFE复合材料孔隙率、BADCy浸入量等对复合材料介电性能及力学性能的影响规律,并用扫描电子显微镜对断口形貌进行了分析。结果表明,当GC/PTFE复合材料的孔隙率为25%时、采用85℃抽真空(0.01 MPa)的浸渍工艺能获得BADCy含量为14.4%(质量分数)的GC/PTFE复合材料,该复合材料具有较优的力学性能和良好的介电性能。湿/热研究表明,经BADCy浸渍后的GC/PTFE复合材料具有较好的耐水煮性能,可满足结构透波材料的使用要求。     

高硅氧/有机硅透波材料性能研究

对低残炭率甲基硅树脂基透波复合材料进行了介电性能和力学性能研究,结果表明,采用低残炭率甲基硅树脂作为透波材料基体研制的透渡复合材料的介电性能优良,经低于1600℃高温处理后,在电磁波频率为9.30GHz时测试的介电常数小于3.5,透波率高达90%以上.采用甲基硅树脂研制的透波材料克服了传统树脂基透波材料耐热性差、强度低的缺点,是集防热、承载、透波和抗烧蚀等功能一体化的较理想的耐高温多功能透波复合材料.     

氧化剂对聚吡咯复合材料介电性能的影响

为了探究氧化剂对聚吡咯复合材料介电性能的影响,以吡咯为单体,采用原位聚合法制备了聚吡咯涂层复合材料。通过BDS50介电谱仪研究了氧化剂种类和氧化剂物质的量浓度对复合材料介电常数实部、虚部、损耗角正切、表面电阻的影响;采用Quanta200型环境扫描电子显微镜和Instron万能材料试验机研究了聚吡咯涂层复合材料的外观形貌和强度。结果表明:氧化剂种类、氧化剂浓度对聚吡咯涂层复合材料介电常数实部、虚部、损耗角正切、表面电阻影响较大;制备的聚吡咯涂层复合材料既具备良好的介电性能和导电性,又兼具良好的强度.     

The effect of thermoplastic coating on the mechanical properties of woven fabric carbon/epoxy composites

The effect of a polyetherimide (PEI) coating on the mechanical properties of woven fabric carbon/epoxy composites was investigated by thermal mechanical analysis, fractographical analysis and mechanical properties measurements. PEI coating enhanced the mechanical properties of carbon/epoxy composites mainly through the improvement of matrix properties. This was because most of the PEI coated on the carbon fiber diffused into the bulk of epoxy matrix due to its good miscibility with epoxy resin. As for mechanical properties of woven fabric carbon/epoxy composites, the extent of improvement by PEI coating highly depended on the applied stress state. Among the mechanical properties, mode II delamination resistance of carbon/epoxy composites showed the highest increment because matrix shear property played an important role in delamination resistance of woven fabric carbon/epoxy composite. Because of the woven geometry of carbon fiber, the improvement in impact property of carbon/epoxy composite was trivial except the large amount of PEI coated case.     

The influence of heat treatment and finishing on the mechanical and dielectric properties of glass fabric-epoxy resin laminar composites

The aim of this investigation was to define the optimum conditions of obtaining glass fabric-epoxy resin laminar composites with mechanical and dielectric properties that satisfy the quality needed for production of printed circuit boards for microelectronics. Commercial materials: glass woven fabric, different types of silane finish and epoxy resin were the starting materials in obtaining composites. The conditions needed for the thermal removal of the original size from glass fabric were investigated. The optimal heat treatment should be performed at temperatures less than 550 °C, while cooling rates should be as low as possible. In this manner, the fabric has less than 0.1% of residual size, and the mechanical properties remain satisfactory. Different types of adhesion promoters based on silanes were applied on heat-treated glass fabric as finishes. The quality of the composite material made of thermally and chemically treated glass fabric and epoxy resin was controled by measuring the tensile and dielectric strength of the composite. Depending on which properties of composite are of primary concern, mechanical or dielectric, a finish with an amino functional group and lower heat-treatment temperature or epoxy-modified coatings and higher heat-treatment temperature should be used for obtaining glass-fabric epoxy resin laminar composites.     

蜂窝状三维整体机织结构型吸波复合材料的设计、制备与性能

为了解决蜂窝夹层结构材料的开裂和分层问题,以玄武岩纤维长丝纱和碳纤维长丝纱为原料,在普通织机上,经合理设计,织造了顶层为透波层、中间层为吸波层和底面为反射层的蜂窝状三维整体机织结构型吸波织物;其次,以蜂窝状三维整体机织结构型吸波织物为增强体,双酚A型环氧树脂为基体,羰基铁粉(CIP)和炭黑(CB)为吸波剂,采用真空辅助树脂传递模塑(VARTM)成型工艺,制备了不同结构参数的蜂窝状三维整体机织结构型吸波复合材料;最后,采用矢量网络分析仪和万能试验机分别对蜂窝状三维整体机织结构型吸波复合材料的吸波性能和力学性能进行研究。研究表明,其有良好的整体性能,兼具吸波和承载能力。     

Dielectric modeling of multiphase composites

In this paper effective medium theory based on Clausius–Mossoti relation was used to predict dielectric properties of multiphase composite system. The composite consisted of E-glass fibers (plain weave S-glass, J.B. Martin) embedded in bisphenol A diglycidylether epoxy matrix (D.E.R. 324, D.O.W. chemicals) with hollow ceramic spherical inclusions (SF 14, P.Q. Corp.) at different volume fractions. In many engineering applications, materials with designed dielectric properties are often sought. An important question in engineering design of a composite material is how the overall properties of the composite depend on those of the individual constituents. Mixing the epoxy resin with hollow ceramic inclusions can effectively reduce dielectric constant of the resin, which is often desirable, rendering composites as good candidates for many applications, especially in telecommunications. Compensation for degradation of mechanical properties of matrix (due to inclusion insertion) is obtained by embedding fibers into the mixture. Measurements of dielectric constant and loss tangent for this multiphase composite system were conducted in the region between 0.1 and 100 kHz range using DEA 290 (T.A. Instruments) dielectric analyzer and experimental results are presented. Good correlation between analytical model and experimental results was observed throughout all frequency range of investigation.     

多层结构的玻璃纤维织物/环氧树脂复合材料的降噪性能评价

根据Kirchhoff-Mindlin理论要求,多层结构面板的隔声性能要考虑到复合结构中流体层和固体层之间的整个交互作用:复杂的声波传递过程中在固体和流体层之间多次反射和系统共振,通过对隔声性能与填充在两层面板之间物质密度的关系,以及对硬质物体的组合和空气层厚度的研究,来探讨评价隔声可变因素及对空腔共振约束的隔声低谷的影响.以玻璃纤维为增强材料,环氧树脂为基体,制备复合树脂板,并设计了多层复合结构,利用混响室-静音箱法对材料隔声性能进行了测试分析.研究表明:多层玻璃纤维织物增强环氧树脂复合材料呈一定的刚性,在各频率的隔声量随着复合材料厚度的增加而增加;声音传播过程中所产生的弯曲波对柔性材料隔声性能的影响远大于对刚性材料的影响.不同颗粒填充多层介质复合材料平均隔声量随材料面密度的增加而增加,与材料面密度的指数成良好的线性相关性.     

拟薄水铝石包覆氧化石墨烯改性环氧树脂-氰酸酯复合材料的微观表征及力学性能

以物理法石墨烯为原料,采用改进的Hummers法制备了氧化石墨烯(GO),通过溶胶-凝胶法在氧化石墨烯表面生长拟薄水铝石(AlOOH)纳米颗粒,得到拟薄水铝石包覆氧化石墨烯(GO@AlOOH),以环氧树脂(E51)和双酚A型氰酸酯(BCE)为原料,GO@AlOOH作为增强体,制备GO@AlOOH/E51-BCE复合材料。采用红外光谱和X射线表征GO@AlOOH,结果表明:AlOOH和GO存在着相互作用,且其表面含有羟基活性基团。复合材料的SEM结果显示:GO@AlOOH的加入使得树脂断裂面明显改变,性能得到提升。当掺杂量为0.6wt%时,复合材料的弯曲强度、弯曲模量以及冲击强度达到最大,分别为158.23 MPa、2.37 GPa和46.96 kJ/m2。该复合材料具有优异的力学性能,具有一定的发展潜力。      

Evaluation of the mechanical behavior of epoxy composite reinforced with Kevlar plain fabric and glass/Kevlar hybrid fabric

In this study, composite plates were manufactured by hand lay-up process with epoxy matrix (DGEBA) reinforced with Kevlar fiber plain fabric and Kevlar/glass hybrid fabric, using to an innovative architecture. Results of the mechanical properties of composites were obtained by tensile, bending and impact tests. These tests were performed in the parallel direction or fill directions of the warp and in a 90° direction. FTIR was used in order to verify the minimum curing time of the resin to perform the mechanical tests, and scanning electron microscopy was used to observe reinforcement and matrix fractures. Composites with Kevlar/glass hybrid structure in the reinforcing fabric showed the better results with respect to specific mechanical strength, as well as bending and impact energy.     

功能化纳米TiO2/环氧树脂超疏水防腐复合涂层的制备与性能

超疏水材料在金属防腐领域具备巨大的潜在应用前景。为得到疏水性能及防腐性能俱优的纳米TiO₂/环氧树脂复合涂层材料,首先以三甲氧基十七氟癸基硅烷和γ-氨丙基三乙氧基硅烷(KH550)对纳米TiO₂表面功能化;以全氟辛基甲基丙烯酸酯对固化剂二乙烯三氨(DETA)进行氟化;最后通过一步共混法和两步喷涂法分别制备出两种复合涂层。利用FTIR、XPS、1HNMR分析氟化固化剂(F-DETA)和氟化纳米TiO₂(f-TiO₂)的物相组成和组织结构。接触角测试仪和静置实验表明,当三甲氧基十七氟癸基硅烷和γ-氨丙基三乙氧基硅烷的摩尔比为1∶15时f-TiO₂的性能最佳,所制备的复合涂层接触角达到164.9°。SEM表征结果显示通过两步法制备的f-TiO₂/环氧树脂复合涂层具备更均匀的粗糙表面、涂层内部孔隙率较低且环氧树脂层与f-TiO₂层具备梯度结构。摩擦实验证明两步法制备的f-TiO₂/环氧树脂复合涂层的超疏水性具备较好的机械稳定性。Tafel极化曲线和电化学阻抗谱(EIS)研究表明,通过两步法制备的f-TiO₂/环氧树脂复合涂层具有优异的防腐性能,其腐蚀抑制效率高达99.99%。