玻璃纤维表面纳米SiO_2改性对GF/PCBT复合材料力学性能的影响

为研究玻璃纤维(GF)表面纳米SiO2改性对GF增强树脂基复合材料力学性能的影响,利用真空辅助模压(VAMP)工艺制备了不同含量的纳米SiO2表面改性GF增强聚环状对苯二甲酸丁二醇酯(PCBT)复合材料。分析了GF表面改性对GF/PCBT复合材料力学性能的影响,研究了纤维表面改性对GF/PCBT复合材料抗湿热老化性能的影响规律。纤维拔出试验结果表明:经表面处理的GF/PCBT复合材料的界面剪切强度提高了1.16倍;采用含量为0.5wt%和2wt%(与树脂质量比)的纳米SiO2处理GF表面后,复合材料的三点弯曲强度分别提高1.5倍和1.67倍,弯曲模量分别提高1.03倍和1.17倍。SEM结果显示:当纳米SiO2用量为2wt%时,破坏后的纤维表面被树脂完全覆盖,树脂与纤维粘结良好。在湿热条件下,由于纳米SiO2颗粒的存在,水分子很难通过界面相扩散到改性后的材料内部,其抗湿热性能提高。     

玻璃纤维单丝拔出实验及其有限元模拟

在细观有限元模型基础上,利用ANSYS有限元程序对不同埋入长度的玻璃纤维/水泥复合材料的纤维拔出行为进行了数值模拟,结合玻璃纤维/水泥复合材料的纤维拔出实验数据验证数值模拟的合理性,并讨论接枝对复合材料拔出行为的影响.结果表明,环氧树脂接枝对复合材料的界面平均剪切强度、破坏模式均有较大影响,与无接枝情况相比,两种接枝中环氧树脂接枝的复合材料界面的平均剪切强度提高了92％;破坏模式与接枝有关,界面破坏导致无接枝玻璃纤维拔出,水泥破坏导致环氧树脂接枝玻璃纤维拔出.此外,还通过有限元分析结果讨论了破坏模式特征及其演化规律,研究结果有助于分析该类复合材料的破坏机理.     

纳米SiO2/玄武岩纤维增强环氧树脂复合材料的制备和耐久性能研究

首先,利用上浆法,将改性纳米SiO2与玄武岩纤维复合;然后利用手工铺料法,制备了纳米SiO2/玄武岩纤维增强环氧树脂层状复合材料(S-BF/EP).利用SEM对改性玄武岩纤维和玄武岩纤维/环氧树脂层状复合材料的表面形貌和界面形貌进行了研究;利用FT-IR、TGA和万能力学试验机对复合材料的分子结构、热解性能和耐久性能进...     

基于内聚力模型的形状记忆合金短纤维增强树脂基复合材料的模拟分析

通过单纤维拔出实验和单轴拉伸实验, 测定了形状记忆合金(SMA)增强树脂基复合材料的界面脱粘剪切强度和单向随机分布SMA短纤维增强复合材料的拉伸强度。根据蒙特卡罗法和边界条件控制方程, 编写了适于软件调用的单向随机分布短纤维增强复合材料的APDL语言生成程序, 建立数值模拟模型。基于指数型内聚力模型, 对SMA纤维与环氧树脂基体界面分离(即界面脱粘)过程进行了有限元模拟。结果表明: 相同纤维体积分数下, 随着纤维长细比的减小, 复合材料整体弹性模量逐渐降低; 温度驱使SMA纤维弹性模量发生变化, 可以有效提高复合材料整体弹性模量。     

提高F-12/环氧复合材料界面性能的方法研究

F-12/环氧复合材料具有优异性能,广泛用于宇航和军事领域.但F-12与环氧树脂基体之间的界面粘结性能较差,复合材料的层间剪切强度较低.针对这一复合材料体系,全面论述了提高F-12/环氧复合材料界面性能的几种方法以及各种方法的优缺点,其中包括纤维表面接枝、偶联、聚合物涂层、冷等离子体、γ射线辐射和超声波技术改性,以及环氧树脂基体纳米SiO2的改性.     

Z-pin的拔出强度试验研究

通过单根Z-pin从复合材料层合板中拔出的试验方法,测试了Z-pin的拔出强度,计算了Z-pin的临界埋入深度,并引入抗拉强度利用率概念来表征Z-pin的抗拉强度在拔出过程中的利用程度.结果表明,直径0.50mm和0.28mm的Z-pin临界埋入深度分别约为5.1mm和3.1mm.当Z-pin的埋入深度小于临界埋入深度...     

碳纤维表面处理对C/PLA复合材料界面粘结强度的影响(Ⅱ)

对硝酸表面处理前后碳纤维增强聚乳酸（Ｃ／ＰＬＡ）复合材料的界面状态进行了研究。重点研究了碳纤维的硝酸表面处理对Ｃ／ＰＬＡ复合材料界面粘结强度的影响以及粘结机理。研究表明,硝酸表面处理可使复合材料的界面粘结强度大幅度增加,复合材料的冲击强度、弯曲强度、弯曲模量和剪切强度亦有不同程度的提高。ＸＰＳ研究发现,央纤维与ＰＬＡ基体间有化学反应发生。界面化学反应程度的增加是复合材料界面粘结强度提高的主要原因;此外,碳纤维表面粗糙度的增加也对界面粘结强度的提高有一定的贡献。     

纳米SiO2改性上浆剂对炭纤维复合材料界面性能的影响

利用单纤维碎裂法，三点短梁法，扫描电镜（SEM）和动态力学热分析（DMTA）研究了未上浆炭纤维、环氧树脂乳液上浆炭纤维和经纳米SiO2改性环氧树脂乳液上浆炭纤维增强树脂基复合材料（CFRP）的界面性能。结果表明：炭纤维经改性乳液上浆剂和未改性乳液上浆剂上浆后，与未上浆相比，其单纤维复合材料的界面剪切强度（IFSS）分别提高了79％和41％，复合材料的层间剪切强度（ILSS）分别提高了14％和9％。DMTA图谱显示经纳米SiO：改性上浆的CFRP其损耗角正切（tanδ）较未改性上浆的降低18％，玻璃化温度（Tg）高出5℃。说明上浆剂中添加纳米SiO2可使上浆后的CFRP界面黏结性得到显著增强。     

γ-射线辐照Armos纤维对AFRC界面性能的影响

为改善Armos纤维和环氧树脂间的界面结合性能,采用对环氧树脂/丙酮溶液浸泡的Armos纤维进行γ-射线辐照改性处理,探索辐照剂量对其芳纶纤维增强复合材料(AFRC)界面性能的影响.研究结果表明:在辐照剂量200～1000kGy,AFRC的层间剪切强度(ILSS)和界面剪切强度(IFSS)均增加,且500kGy界面强度较未处理的提高幅度最大;经γ-射线辐照处理的芳纶纤维,表面氧含量有大幅度提高,使得纤维表面活性增大;辐照处理后纤维表面较未处理的纤维表面粗糙度有所增加;纳米硬度仪测试AFRC横断面纤维、界面和基体的纳米硬度,表明辐照可以提高复合材料的硬度.     

短玻纤增强丙烯腈-丁二烯-苯乙烯共聚物的制备及性能

以丙烯腈-丁二烯-苯乙烯共聚物(ABS)及短玻璃纤维(SGF)为原料, 以苯乙烯-马来酸酐共聚物(SMA)和环氧树脂(EP)为界面相容剂, 制备了SGF/SMA-EP-ABS复合材料。用扫描电镜(SEM)、 动态力学热分析(DMTA)等研究了界面相容剂对SGF增强ABS复合材料力学性能及界面粘结性能的影响。结果表明:加入SMA或EP, SGF增强ABS复合材料的力学性能明显提高; SMA与EP同时加入具有明显的协同效果, 使复合材料的性能更为优越。当SGF加入质量分数为30%时, SGF/SMA-EP-ABS复合材料的拉伸强度、 弯曲强度、 冲击强度较未添加界面相容剂时分别提高了56%、 42%、 79%。SEM和DMTA测试表明, 加入SMA和环氧树脂后, SGF与ABS基体之间的界面粘结性能得到很大改善。      

Improved adhesion between nickel–titanium SMA and polymer matrix via acid treatment and nano-silica particles coating

Shape memory alloy (SMA) composites are the desirable candidate for smart materials that used in intelligent structures. However, the overall mechanical performance of SMA composites depends immensely on the quality of the interaction between SMA and polymer matrix. Therefore, it is necessary to find out an approach to enhance the interfacial property of this composite. In this paper, we modified nickel–titanium SMA wire with nano-silica particles before and after acid treatment. The modification effect on the interfacial strength between SMA and epoxy resin was evaluated. Contact angle analysis, scanning electron microscopy (SEM) observation, and single fiber pull-out test were carried out. The bonding characteristics between modified wire and liquid/cured resin were investigated. We then embedded SMA wire into woven glass fabric/epoxy composite laminates, and manufactured this hybrid composites via vacuum assisted resin transfer molding processing. Three-point-bending test of the hybrid composites was performed to validate the modification effect. Fiber pull-out experiment demonstrates that the interfacial shear strength increases by 6.48% by nano-silica particles coating, while it increases by 52.21% after 8 h acid treatment and nano-silica particles coating simultaneously. For hybrid composites, flexural strength of the two specimens increases by 19.8 and 48.2%, respectively. In SEM observation, we observed large debonding region in unmodified composites, while interfacial adhesion between modified wire and epoxy keeps strong after flexural damage.     

Simulation and analysis of shape memory alloy fiber reinforced composite based on cohesive zone model

Shape memory alloy (SMA) composite has been wildly used in engineering fields as a smart structure. The interface between SMA fiber and matrix plays an important role in determining the effective response of the composites, since it is the medium through which stress transfer occurs. Therefore, it is necessary to investigate how the variation of interfacial properties affects the overall behavior of the composites. In this paper, the interfacial shear strength and ultimate strength of composites are evaluated based on pull-out tests and uniaxial tensile tests, respectively. An algorithm for the automatic generation of unidirectional random distribution short-fiber reinforced composites is developed by using Monte-Carlo method and boundary condition control equation via ANSYS Parameter Design Language (APDL). Cohesive zone model (CZM) approach is used to characterize the interfacial traction separation relationships. Uniaxial tensile test is simulated using finite element method to study the overall macroscopic behavior of the composite through varying fiber ratios and ambient temperatures. The effects of interfacial debonding process, fiber ratios and ambient temperatures on the response of composites are discussed under the same fiber volume fraction.     

碳纤维和SiO2纳米颗粒增强环氧树脂复合材料的压缩性能

纤维增强聚合物复合材料的压缩性能与聚合物基体力学性质密切相关。本文利用连续碳纤维（CF）和含有均匀分散的SiO₂纳米颗粒改性的环氧树脂基体,制备了CF-nano SiO₂/Epoxy微纳米多相复合材料单向层合板,并对其轴向压缩性能进行了系统的研究。试验表明,将纳米颗粒引入基体能够有效提高纤维增强聚合物基复合材料的压缩强度,占nano SiO₂/Epoxy体积为8.7%的纳米颗粒可将复合材料的压缩强度提升约62.7%。基于单向层合板的弹塑性微屈曲模型对纳米颗粒的增强效应进行了理论分析。根据含纳米颗粒的环氧树脂在压缩过程中的损伤行为,提出了一套基于加卸载试验建立纳米复合材料基体压缩本构关系的方法。将模型获得的基体本构关系与经典复合材料弹塑性微屈曲模型耦合,能够较为准确地预测本研究制备的微纳米多相复合材料的压缩强度。经试验检验,预测结果与实测数值达到很好的一致性。      

CVD SiC fiber-reinforced barium aluminosilicate glass—ceramic matrix composites

Unidirectional CVD SiC (SCS-6) monofilament reinforced BaOAl₂O₃2SiO₂(BAS) glass—ceramic matrix composites have been fabricated by a tape lay-up method followed by hot pressing. The glass matrix flows around fibers during hot pressing resulting in nearly fully dense (95–98%) composites. Strong and tough composites having first matrix cracking stress of 250–300 MPa and ultimate flexural strength as high as 900 MPa have been obtained. Composite fracture surfaces showed fiber pullout with no chemical reaction at the fiber/matrix interface. From fiber push out, the fiber/matrix interfacial debond strength and the sliding frictional stress were determined to be 5.9 ± 1.2 MPa and 4.8 ± 0.9 MPa, respectively. The fracture surface of an uncoated SiC (SCS-0)/BAS composite also showed fiber/matrix debonding, fiber pullout, and crack deflection around the fibers implying that the SiC fibers may need no surface coating for reinforcement of the BAS glass-ceramic. Applicability of micromechanical models in predicting the first matrix cracking stress and the ultimate strength of these composites has also been examined.     

改性纳米SiO2/硅橡胶复合材料的制备及性能

为提高纳米SiO₂在硅橡胶（SR）基体中的分散性及两相间的界面结合力,设计以羟基硅油（HSO）和γ-甲基丙烯酰氧基丙基三甲氧基硅烷（KH570）为纳米SiO₂的表面封端改性剂,并将改性SiO₂与双组份加成型液体SR复合得到改性纳米SiO₂/SR复合材料。通过一系列表征手段对改性纳米SiO₂的形貌结构及其在乙醇中的分散性等进行分析,研究了改性纳米SiO₂对纳米SiO₂/SR复合材料的断面形貌、力学性能及热稳定性的影响。结果表明:KH570成功接枝到纳米SiO₂表面并与SR基体间形成化学键。当HSO协同KH570改性纳米SiO₂时,可有效改善纳米SiO₂在SR基体中的分散性能及纳米SiO₂与SR两相间的界面结合性能,并显著提高纳米SiO₂/SR复合材料的力学性能和热稳定性。将SiO₂∶HSO∶KH570以质量比为2.0∶0.2∶0.6处理的改性纳米SiO₂粒子,得到的改性纳米SiO₂/SR复合材料起始热分解温度提高了230℃。当SiO₂∶HSO∶KH570质量比为2.0∶0.2∶0.45时,改性纳米SiO₂/SR复合材料的拉伸强度和断裂伸长率分别提高了约1倍。      

高强玻纤增强ABS复合材料的制备及性能

以丙烯腈-丁二烯-苯乙烯共聚物(ABS)及玻璃纤维(GF)为原料,以苯乙烯-马来酸酐共聚物(SMA)和环氧树脂(E-poxyresin)作为界面相容剂,研究了界面相容剂对玻璃纤维增强ABS复合材料力学性能及界面粘接的影响。结果表明,加入SMA或环氧树脂,玻纤增强ABS复合材料的力学性能明显提高;SMA与环氧树脂复配有明显的协同效果,同时加入SMA和环氧树脂后的复合材料的性能更加优越,界面粘接性能得到很大的改善,在玻纤加入量为30%时,其拉伸强度、弯曲强度、冲击强度较未添加界面相容剂时分别提高了44%、29%、100%。     

Fabrication and mechanical properties of aramid/nylon plain knitted composites

The presence of fibre/matrix interfaces strongly influences the overall mechanical properties of composites. In order to produce fully recyclable fiber reinforced composites with improved adhesion properties, polyethylene and polypropylene materials were previously used as single-polymer composite materials. In this paper, another breed of single-polymer composite material has been defined as the ‘one-unity’ composite. Polyamide materials were chosen and combined with aramid fibre in an attempt to achieve better interfacial bonding. Weft-knitting technique was used to produce textile reinforcements for aramid/nylon composite processing. Aramid/epoxy knitted composites were also fabricated to compare them with aramid/nylon thermoplastic composites. Mechanical properties of aramid/nylon and aramid/epoxy composites and their relationships to the fibre/matrix interfacial adhesion and interactions have been investigated. With the increase in processing time, tensile modulus and strength of aramid/nylon composites have increased and decreased, respectively. Furthermore, scanning electron microscopic observations clearly indicated that longer molding time has resulted in stronger adhesion property between fiber and matrix. Aramid/nylon knitted composites have revealed comparable strength property in the course direction, albeit they have inferior tensile strength in the wale direction when compared to that in aramid/epoxy composites. In aramid/nylon knitted composites, while tensile modulus exhibited an increasing trend, there were clear drops in tensile strengths with longer molding time. This indicates that there could be an optimum molding condition at which maximum tensile properties can be obtained. Aramid/nylon knitted composites exhibited relatively better interfacial bonding properties than Aramid/epoxy composites, which suffered fibre/matrix debonding.     

Process and mechanical properties of carbon/carbon–silicon carbide composite reinforced with carbon nanotubes grown in situ

A hierarchical C_f/C–SiC composite was fabricated via in situ growth of carbon nanotubes (CNTs) on fiber cloths following polymer impregnation and pyrolysis process. The effects of CNTs grown in situ on mechanical properties of the composite, such as flexural strength, fracture toughness, crack propagation behavior and interfacial bonding strength, were evaluated. Fiber push-out test showed that the interfacial bonding strength between fiber and matrix was enhanced by CNTs grown in situ. The propagation of cracks into and in fiber bundles was impeded, which results in decreased crack density and a “pull-out of fiber bundle” failure mode. The flexural strength was increased while the fracture toughness was not improved significantly due to the decreased crack density and few interfacial debonding between fiber and matrix, although the local toughness can be improved by the pull-out of CNTs.     

Effect of interfacial adhesion and statistical fiber strength on tensile strength of unidirectional glass fiber/epoxy composites. Part I: experiment results

The effects of fiber surface treatment on ultimate tensile strength (UTS) of unidirectional (UD) epoxy resin matrix composites are examined experimentally. The interfacial shear strength (IFSS) and statistical fiber strength are significantly altered by five different kinds of surface treatments, which are: (a) unsized and untreated; (b) γ-glycidoxypropyltrimethoxysilane (γ-GPS); (c) γ-methacryloxypropyltrimethoxysilane (γ-MPS); (d) mixture of γ-aminoxypropyltrimethoxysilane (γ-APS), film former (urethane) and lubricant (paraffin); and (e) urethane-sized. The maximum UTS is obtained for the relatively strong interfacial adhesion (glass/γ-MPS/epoxy) but not for the strongest interfacial adhesion (glass/γ-GPS/epoxy). The governing micro-damage mode around a broken fiber and the interface region is matrix cracking for γ-GPS treated fibers, and a combination of interfacial debonding and matrix cracking for γ-MPS treated fibers. The micro-damage mode related to the interfacial adhesion strongly affects the fracture process, and thus the UTS of UD composites. The results also indicate that the interfacial adhesion can be optimized for effective utilization of fiber strength for fiber composites. A parameter called “efficiency ratio” of fiber strength in UD composites is proposed to examine and distinguish different effects of IFSS and fiber strength on the UTS of UD composites. The experimental results show that improved UTS of UD composites due to surface treatments mainly result from the increase in fiber strength but not from the modified interface.