LiCl处理对芳纶纤维表面结构与性能的影响

为提高芳纶纤维与复合材料基体间的界面强度,首先,使用LiCl乙醇溶液处理芳纶纤维一定时间;然后,对LiCl处理芳纶纤维表面的化学组成、微观形貌、单丝拉伸强度及芳纶纤维/环氧树脂复合材料的界面性能等进行了测试分析。结果表明:使用LiCl乙醇溶液处理芳纶纤维后,芳纶纤维表面的含氮官能团含量增加;处理后,芳纶纤维表面有刻蚀出的沟槽,表面粗糙度增大,进而改善了芳纶纤维与环氧树脂基体的界面粘接性能,使芳纶纤维/环氧树脂复合材料的层间剪切强度由处理前的21.75 MPa提升到37.98 MPa;最佳处理时间为3~4 h,而处理时间过长会导致芳纶纤维的单丝拉伸强度及复合材料的层间剪切强度下降。所得结论证实使用LiCl处理芳纶纤维是一种有效的表面改性方法。      

碳纤维/乙烯基酯树脂拉挤复合材料界面性能研究

对PAN基碳纤维在线热氧化表面处理,分析了处理前后碳纤维的表面形貌,通过拉挤成型工艺制备出碳纤维/乙烯基酯树脂复合材料。对拉挤复合材料的微观结构观察以及力学性能测试表明:碳纤维经表面处理后表面粗糙度增加,与乙烯基酯树脂的界面粘结性明显改善,复合材料的力学性能尤其是层间剪切强度得到显著提高。对不同界面性能的碳纤维复合材料进行动态热机械分析(DMTA),认为界面性能的改善可降低损耗模量,提高复合材料的耐疲劳性能。     

界面柔性层对玻璃纤维毡增强聚丙烯复合材料力学性能的影响

通过橡胶分子链在玻璃纤维表面的接枝,在玻璃纤维毡增强聚丙烯复合体系中引入了界面柔性层,研究了柔性层的种类及厚度对复合体系界面结合及力学性能的影响,结果表明,采用容易与玻璃纤维表面形成化学键等牢固结合与基体树脂有一定相容性的橡胶分子链作为界面柔性层,可以获得高强度,高抗冲的玻璃纤维毡增强聚丙烯复合材料,柔性层的厚度对复合体系的力学性能有很大的影响,超过一定的厚度后,随着柔性层的增厚,玻璃纤维增强聚丙烯复合材料的力学性能呈下降的趋势。     

水分在粘接接头界面的扩散系数和动力学

为研究水分在粘接接头界面的扩散行为,采用X射线能谱（EDX）分析方法计算了水分在碳／碳复合材料粘接接头界面的扩散系数和扩散动力学,并比较了水分在不同表面处理方法处理的碳／碳复合材料粘接接头界面的扩散系数和扩散动力学．结果表明,经偶联剂处理的碳／碳复合材料耐久性能要好于化学氧化和砂纸打磨处理,这与剪切强度测试结果相一致．     

多巴胺处理芳纶对增强天然橡胶复合材料性能的影响

采用磷酸溶液对芳纶纤维进行表面处理,再用多巴胺对纤维进行涂覆,将得到的纤维经过环氧(溶于丙酮溶液中)的浸泡,将处理后的纤维、液体橡胶和天然橡胶制成母炼胶,制备芳纶纤维增强天然橡胶的复合材料。考察了磷酸、多巴胺、环氧对纤维的改性效果及对复合材料力学性能的影响。红外光谱、扫描电镜检测表明芳纶的改性改善了纤维表面与复合材料间的界面粘接,力学性能显示多巴胺、环氧对芳纶纤维的处理使复合材料的力学性能提高,几乎都提高了20%以上。橡胶加工流变性能分析表明不同的改性都增大了复合材料的储能模量和损耗模量,从而改善了纤维与橡胶基体的界面粘合。     

铝合金裂纹板的阳极化处理与复合材料补片胶接修理效果

采用磷酸阳极化方法对胶接修理铝合金裂纹板的粘接表面进行了处理,并用单向碳纤维/环氧复合材料补片对铝合金进行了修补.测试了阳极化铝合金的粘接性能、修补结构的静态力学性能和疲劳性能,考察了粘接表面的阳极化处理对修补结构的静态力学性能和疲劳性能的影响.结果表明,磷酸阳极化在铝合金表面形成多孔膜,复合材料补片修补胶接时胶粘剂能渗透进入阳极化铝合金表面的多孔膜,在粘接界面上形成一层过渡层,该过渡层的形成能有效提高其与复合材料的粘接性能,其粘接副的拉剪强度提高了104%;铝合金裂纹板胶接修理前的粘接表面的阳极化处理能大幅度地提高修复结构的静态强度和疲劳寿命,当用单向碳纤维/环氧复合材料补片单面修补时,修补结构的破坏强度为418.13MPa,恢复到完好板的93.42%;修补结构的疲劳寿命相对裂纹板延长了1.42倍,比未阳极化的修补板的疲劳寿命增加了27.59%.修补前的阳极化处理也使修补结构在一定周次疲劳后的剩余强度有所提高.     

PVP塑性界面层对CF/VE复合材料性能的影响

用热塑性聚乙烯吡咯烷酮(PVP)对商用炭纤雏(CF)表面进行不同的涂覆处理后，制备了炭纤维／乙烯基酯树脂基单向复合材料(CF／VE)。研究了PVP塑性界面层对复合材料的层间剪切强度(ILSS)、弯曲性能、断口形貌及动态热机械性能的影响。结果表明。在炭纤维保持原环氧上胶层的基础上直接涂覆PVP时。复合材料的ILSS和弯曲性能提高，纤维与乙烯基酯树脂基体的粘结性能得到改善；炭纤维脱除原环氧上胶层后涂覆PVP时。复合材料的ILSS和弯曲强度降低，纤维与基体的粘结性能变差；塑性PVP界面层的存在使复合材料的玻璃化转变温度(Tg)和弯曲模量提高，储能模量(E’)和能量损耗增大。     

硅烷偶联剂对电子束固化碳纤维复合材料界面的增效研究

根据碳纤维表面的特点及其复合材料中树脂基体进行电子束固化的机理,对碳纤维表面进行预氧化以提高碳纤维表面含氧宫能团的含量,利用偶联剂的化学架桥作用对电子束固化复合材料界面进行了增效研究.采用X射线光电子能谱(XPS)对处理后碳纤维表面化学成分进行了分析,并采用层间剪切强度对电子束固化复合材料界面粘合性能进行了评价.结果表明,碳纤维表面的含氮官能团使电子束固化复合材料中碳纤维与环氧树脂基体之间的粘合强度减弱,偶联剂与预氧化碳纤维表面进行了强相互作用,使电子束固化复合材料层间剪切强度得到提高.     

硅烷偶联剂对电子束固化碳纤维复合材料的增效研究

根据碳纤维表面的特点及其复合材料中树脂基体进行电子束固化的机理,对碳纤维表面进行预氧化以提高碳纤维表面含氧官能团的含量,利用偶联剂的化学架桥作用对电子束固化复合材料界面进行了增效研究。采用X射线光电子能谱（XPS）对处理后碳纤维表面化学成分进行了分析,并采用层间剪切强度对电子束固化复合材料界面粘合性能进行了评价。结果表明,碳纤维表面的含氮官能团使电子束固化复合材料中碳纤维与环氧树脂基体之间的粘合强度减弱,偶联剂与预氧化碳纤维表面进行了强相互作用,使电子束固化复合材料层间剪切强度得到提高。     

剑麻/聚丙烯复合材料的冲击性能及其预测

采用注塑工艺制备剑麻纤维增强聚丙烯复合材料,研究纤维含量、长度及其分布、不同基体树脂和相容剂类型等对复合材料冲击性能的影响。分析单纤维强度的分散性,采用修正的Weibull分布模型估算临界纤维强度,并对复合材料的冲击强度进行预测。结果表明：剑麻/聚丙烯的冲击强度随纤维含量增加而升高,树脂基体的性质对冲击强度具有显著的作用;界面层为刚性层的相容剂MAPP对冲击强度具有负作用,而界面层为柔性层的相容剂PP-g-GMA对冲击强度具有提高作用;同等含量下,使用PP-g-GMA后复合材料的冲击强度比使用MAPP提高21.7%。通过KH550硅烷溶液处理后的纤维与PP-g-GMA反应,在界面处引入更加柔性的界面层,使冲击强度比引入MAPP提高50.7%。将纤维取向因子引入冲击强度模型后,预测值与实测值符合较好。     

物理气相沉积黄铜镀层对钛丝绳和橡胶粘合性能的影响研究

利用物理气相沉积(PVD)在钛丝绳表面沉积黄铜镀层,研究了钛基体表面处理、黄铜镀层成分、镀层厚度以及镀层形貌对钛丝绳和橡胶粘合力的影响.结果表明,有效去除钛基体表面钝化层并采用打底过渡层方式,可以提高黄铜镀层和钛基体的结合力;钛丝绳和橡胶粘合力随着黄铜镀层中Zn含量的升高而增加,Zn≥30％时进入增长平台区;镀层厚度增...     

粉煤灰微珠-TiO_2复合颗粒制备与性能表征

以粉煤灰微珠为基体,利用TiOSO_4水解法,制备TiO_2包覆微珠复合颗拉。通过扫描电镜、X射线衍射、比表面积、超声振荡和光电子能谱等检测手段,对复合微珠的表面形貌、包覆层相组成、比表面积、包覆层与基体结合强度与结合方式进行了研究和探讨。检测与分析表明:得到的复合微珠表面包覆层为均匀非连续包覆,包覆层主要为金红石相,包覆后微珠比表面积比未包覆前提高了超过600倍,且包覆层颗粒与基体结合强度较高,二者间存在化学键的联结。     

双键超支化聚硅氧烷在芳纶纤维表面的原位生长

以显著提升芳纶纤维与橡胶基体之间的界面结合强度为目标,本文开发了一种在芳纶纤维表面原位生长碳碳双键超支化聚硅氧烷的策略:首先借助多巴胺的仿生修饰建立初始层,接着采用迈克尔加成反应接枝氨基硅烷偶联剂创建中间层,最后通过脱水缩合反应实现原位生长。改性前后的芳纶纤维表面形貌和化学结构采用扫描电镜、傅里叶变换红外线光谱分析仪、X射线光电子能谱分析仪及热失重分析仪进行了测试表征。由芳纶纤维增强橡胶基复合材料的H-抽出力测试结果可得,本文采用的改性方法能够提升约66.4%的界面结合强度,其原因主要可以归结为表面粗糙度的提升及纤维束与橡胶共硫化的实现。对比分析发现,聚多巴胺初始层的采用使本改性方法具有较高的普适性和工业应用潜力。      

迷彩橡塑复合胶布研制

目的研制一种用于封套的具有高阻隔、可热封、耐候性能优异的迷彩橡塑复合胶布。方法在比较不同封套材料的基础上,采用铺层结构设计,以丁基胶布为阻隔层,聚酯纤维为基材层,聚氨酯涂覆薄膜为耐磨热封层,通过橡胶胶布刮涂制造工艺制成。结果通过对聚氨酯涂层织物的预处理,解决了覆层材料-丁基橡胶与骨架材料-聚酯纤维难粘合的问题,经涂胶,停放72 h内合布、硫化,制得的迷彩橡塑复合胶布其透湿率为2.19 g/(m2·24 h)。结论整合了现有资源,从材料性能设计、结构铺层设计及功能层材料选用等封套包装复合材料设计的关键环节入手,解决了传统橡胶胶布加工制作的封套在用于大型装备野外封存时存在现场施工不便利,工艺性不佳的缺点,满足了对大型装备实施野外长期封存的需求。     

Interfacial interactions in clay-based nylon 6 nanocomposites: A density functional theory study

Density functional theory was used to study the interfacial interactions between clay and polymer in polymer/clay nanocomposites, with a focus on nylon 6 matrix. The binding energy and the distance between nylon 6 and clay surface were predicted. The effect of the isomorphic substitution in clay octahedral and tetrahedral layer on the strength of the interfacial interactions was also examined. The interaction strength between nylon 6 and clay surface was found to increase with the degree of isomorphic substitution. And the magnitude of the binding forces, reflected from the calculated binding energies, was found to be higher when the substitution took place in tetrahedral layer (e.g., Al³⁺ for Si⁴⁺). No covalent bonds were observed between nylon 6 and the clay, which means that the chemical structures of the clay and nylon 6 are unchanged during the mixing process.     

Variation of roughness and adhesion strength of deposited apatite layers on titanium dental implants

It is known that surface roughness and chemical composition of the titanium surface influence the osseointegration of titanium implants. Most commercial dental implants offer a shot-blasted rough surface. It is also known that apatite layers coating the surface of titanium implants improve bone response, but the adhesion of the layer to the substrate poses some problems.In this study the roughness and adhesion strength to a titanium dental implant surface of an apatite layer deposited via wet chemistry after a thermochemical treatment were compared with those of plasma-sprayed apatite layers and machined titanium surfaces. Different surface conditions have been studied: (a) as-received machined dental implant surface; (b) grit-blasted titanium surface; (c) grit-blasted and thermochemically-treated titanium surface; (d) titanium surfaces coated with plasma-sprayed apatite. The morphology and roughness of the samples were measured and compared. The adhesion of the apatite layers to the titanium was compared by means of a scratch test.Measured roughness showed that the deposition of an apatite layer did not affect roughness but plasma-sprayed apatite produced a decrease on roughness values when compared to control samples. Both roughness and adhesion strength of the deposited apatite layer to the titanium substrate were higher than those of the plasma-sprayed apatite.     

超细绢云母/加成型液体硅橡胶复合材料的制备及性能

以天然绢云母矿物为原料,利用气流磨超细粉碎、乙烯基三乙氧基硅烷表面修饰处理对绢云母进行深加工,得到有机化的绢云母超细粉体,再采用溶液聚合方法制备出具有优良性能的超细绢云母/加成型液体硅橡胶复合材料。用SEM对其微观形貌进行了观察和分析,通过观察SEM可以发现经偶联剂表面修饰处理后超细绢云母在硅橡胶基体中分散均匀。当超细绢云母质量分数为8%时,复合材料的拉伸强度和邵氏硬度达到了1.25 MPa和61,分别比纯硅橡胶提高了197.62%和48.78%。TGA测试结果表明,超细绢云母可显著提高硅橡胶的热稳定性能。此外,用Kraus方程对超细绢云母与硅橡胶之间的相互作用进行了表征。      

H_2O_2处理碳包覆铁纳米颗粒的表面特性及分散行为

采用体积分数30%的H2O2处理碳包覆铁纳米粒子外层的非晶态类石墨碳层,并将其超声分散于水介质中,通过改变pH值分析测定碳包覆铁纳米粒子表面zeta电位和粒径。结果表明:碳包覆铁纳米粒子非晶碳层的特殊结构可通过双氧水化学处理使其表面产生羧基和羟基;在强碱性介质下,羟基和羧基可强化颗粒间的静电斥力,提高碳包覆铁纳米粒子在水介质中的分散性能。当pH值约为11.5时,碳包覆铁纳米粒子表面zeta电位为48 mV,水合粒子粒径可达到110 nm。     

Effects of HF treatments on tensile strength of Hi-Nicalon fibres

Tensile strengths of as-received Hi-Nicalon fibres and those having a dual BN–SiC surface coating, deposited by chemical vapour deposition, have been measured at room temperature. These fibres were also treated with HF for 24 h followed by tensile strength measurements. Strengths of uncoated and BN–SiC coated Hi-Nicalon fibres extracted from celsian matrix composites, by dissolving away the matrix in HF for 24 h, were also determined. The average tensile strength of uncoated Hi-Nicalon was 3.19±0.73 GPa with a Weibull modulus of 5.41. The Hi-Nicalon–BN–SiC fibres showed an average strength of 3.04±0.53 GPa and Weibull modulus of 6.66. After HF treatment, the average strengths of the uncoated and BN–SiC coated Hi-Nicalon fibres were 2.69±0.67 and 2.80±0.53 GPa and the Weibull moduli were 4.93 and 5.96, respectively. The BN–SiC coated fibres extracted from the celsian matrix composite exhibited a strength of 2.38±0.40 GPa and a Weibull modulus of 7.15. The strength of the uncoated Hi-Nicalon fibres in the composite was so severely degraded that they disintegrated into small fragments during extraction with HF. The uncoated fibres probably undergo mechanical surface damage during hot pressing of the composites. Also, the BN layer on the coated fibres acts as a compliant layer, which protects the fibres from mechanical damage during composite processing. The elemental composition and thickness of the fibre coatings were determined using scanning Auger analysis. Microstructural analyses of the fibres and the coatings were done by scanning electron microscopy and transmission electron microscopy. Stengths of fibres calculated using average and measured fibre diameters were in good agreement. Thus, the strengths of fibres can be evaluated using an average fibre diameter instead of the measured diameter of each filament. © 1998 Kluwer Academic Publishers     

Experimental investigation on the dynamic response of scaled ship model with rubber sandwich coatings subjected to underwater explosion

How to moderate ship the damages caused by the underwater explosions is of great interest to the modern ship designers. This investigation explores the protective effects of a layer of rubber sandwich with the square honeycomb core coated onto ship hull. Two slender steel scaled ship models were manufactured and tested. One model was coated with a layer of rubber coating while the other kept intact. A series of comparative tests were carried out to comprehend the dynamic performance of the protective layer when both shock wave and bubble pulse loading were considered. Modal characteristics of both models were measured firstly and then live UNDEX tests were made on the free floating ship models. The acceleration and strain peaks were selected as the major comparative criterions. The free field and wall pressure were also monitored. Detailed discussions on test results show that the protective rubber layer is capable of moderating damage of the ship body caused by shock wave while not very effective in reducing the whipping damage excited by bubble pulse.