PET纤维/环氧复合材料界面性能改性研究

PET纤维表面呈惰性、不易与树脂浸润，有必要对PET纤维表面进行处理，提高PET纤维的的表面活性，进而提高PET纤维／环氧复合材料界面性能．采用冷等离子体技术对PErr纤维进行表面处理，利用ESCA和SEM分析了冷等离子体处理前后PET纤维表面的元素组成和层间剪切断口形貌的变化；研究了冷等离子处理前后浸润性、PET纤维／环氧复合材料界面性能的变化。结果表明：经冷等离子体处理PET纤维表面含氧和氮的极性基团增加、浸润性改善显著，进而使涤纶纤维／环氧复合材料界面剪切强度提高。     

单纤维复合材料断裂实验表征界面研究

对不同表面处理剂处理的4种单纤维增强环氧基复合材料进行了断裂实验，从临界纤维长度、界面剪切强度和单纤维断裂实验中纤维断点周围基体形貌三方面对纤维和基体之间的界面粘结性能进行了分析和评价。实验观察得到的结果是KH-550处理纤维与环氧的界面粘结最强，其次是KH-550和KH-570混合处理纤维与环氧的界面、KH-570处理纤维与环氧的界面，最弱的是水处理纤维与环氧的界面。     

石墨纤维连续化冷等离子体表面处理

本文利用冷等离子体技术对石墨纤维表面进行了连续空气冷等离子表面处理。结果表明:经等离子体处理后,石墨纤维与基体树脂间的粘结性得到大大改善,其复合材科的层间剪切强度比未处理的提高138％,抗拉强度和杨氏模量也分别增加了11.3％和7％。复合材料层间剪切强度的增加可能是由三种因素促成的:其一纤维表面—COOH,OH,=O等含氧基团的增加,提高了纤维与基体的反应能力;其二纤维表面无定形碳含量的增加,增加了纤维表面活性;其三纤维表面沟槽加深,扩大了粘结界面和机械联结强度;其中—COOH的贡献可能更大一些。另外,此种处理方法工艺简单,且经济、安全、无公害,可与石墨纤维生产线配套使用。     

聚吡咯层对聚酯/环氧树脂界面粘结性能的影响

采用吡咯化学沉积聚合方法对聚酯(PET)纤维进行表面改性,研究聚合工艺条件对纤维与环氧树脂界面剪切强度的影响.分别用SEM、共聚焦显微镜、DMA及单纤维拔出实验等测试手段对改性前后纤维的表面形貌、粗糙度、聚吡咯(PPy)与基体纤维大分子作用力及复合材料的界面剪切强度(IFSS)进行研究.结果表明:吡咯化学沉积聚合改性是一种有效提高纤维与树脂界面粘结性能的方法.此外,可进一步通过聚合改性工艺条件控制聚吡咯层的形貌及聚吡咯与基体纤维大分子的作用力,从而调控纤维与树脂界面剪切强度,吡咯气相化学沉积后再液相沉积,增强复合材料界面剪切强度比原纤维的提高了127.98%.     

基于常压协同射流等离子体改性国产高强中模碳纤维表面的研究

国产高强中模碳纤维性能优异,但其表面活性低,与树脂基体的结合能力较差。为了改善国产高强中模碳纤维表面活性,提高其与环氧树脂的界面性能,采用常压脉冲放电与射频放电协同的射流等离子体放电形式,对碳纤维表面进行改性处理,并系统研究了改性前后碳纤维的表面形貌、单丝强度、与环氧树脂的接触角、表面O/C比、含氧活性基团含量、复合材料层间剪切强度(ILSS)等参量。结果发现:等离子体处理3次时(约为120 s)碳纤维表面性能最佳,与原样相比,其接触角降低了21.3%,O/C比提升了53.3%,C1s峰上的C-O和COOH含量分别提高了95.61%与179.37%,复合材料的层间剪切强度提高了64.49%,说明其界面性能得到了大幅度提升。此外,常压协同射流等离子处理对纤维本体未造成明显损伤,且一定程度上起到修复纤维表面疵点的作用,增加了表面粗糙度,有效提高了碳纤维对树脂的浸润性能。     

冷等离子体改性对芒果种子纤维表面性能的影响

利用冷等离子体技术对芒果种子纤维进行表面改性处理,对冷等离子体改性前后芒果种子纤维表面的形貌结构、静态接触角及动态表面浸润性进行分析表征和研究,结果表明:未经过冷等离子体表面改性的芒果纤维表面较为平滑光洁,表面呈现负浸润,接触角的滞后现象不明显;经过冷等离子体表面改性后,芒果纤维表面刻痕明显,并随着处理时间由5 min增加到15 min,接触角由84. 1°降低到44. 5°,纤维表面呈现正浸润,滞后角由20. 50°提高到32. 41°,滞后现象明显,浸润性能得到了较大的提升.     

芳纶Ⅲ的氧气等离子的表面改性

为改善芳纶纤维复合材料的界面粘结性能,采用氧气等离子体对芳纶Ⅲ进行表面改性,制备了芳纶环氧复合材料,采用扫描电子显微镜(SEM)、X射线光电子能谱仪(XPS)分析、动态接触角(DCA)分析、测定拉伸强度、弯曲强度等测试方法来研究改性处理效果.结果表明:经等离子处理后,纤维表面m(O)/m(C)比提高,纤维表面粗糙度明显增大,与水的润湿角变小,弯曲强度较未处理提高了30%.     

多巴胺仿生修饰及聚乙烯亚胺二次功能化表面改性超高分子量聚乙烯纤维

为提高超高分子量聚乙烯(UHMWPE)纤维与环氧树脂之间的界面剪切强度,采用多巴胺仿生修饰及聚乙烯亚胺(PEI)二次功能化对UHMWPE纤维进行表面改性,并通过FTIR、XPS、SEM和单丝拔出实验等方法分析改性前后UHMWPE纤维的表面特征及UHMWPE/环氧树脂复合材料的界面剪切破坏情况.结果表明:经过多巴胺涂覆和PEI二次功能化后的纤维表面产生羟基和氨基等活性官能团;改性后的纤维表面粗糙度增加;改性前后纤维力学性能基本不变;改性后的UHMWPE纤维与环氧树脂之间的界面剪切强度有所增加,当PEI质量浓度为5 mg/m L时,PEI二次功能化后的UHMWPE纤维与环氧树脂之间的界面剪切强度为1.185 MPa,与未改性UHMWPE纤维复合材料相比,提高了65.27%.     

涤纶等离子体表面改性及粘结性研究

本文采用等离子体处理，对涤纶纤维表面进行改性，以提高纤维的浸润性和粘结性。文中运用接触角测量反映纤维经处理后的表面能变化，并用独特设计的制祥和测试方法探讨涤纶处理前后的粘结效果。实验结果表明，该测试方法简便可行且定量准确，能较好地反映纤维的结效果。涤纶纤维经等离子体处理后，其粘结性能有较大的提高。     

连续表面处理超高分子量聚乙烯纤维的研究

用不同方法对超高分子量聚乙烯（UHMWPE）纤维进行连续表面处理,研究了不同处理液和处理工艺对UHMWPE纤维增强复合材料界面粘结强度的影响.用扫描电子显微镜、偏光显微镜等方法,分析了处理前后纤维表面性能、表面形貌的变化.研究结果表明,经过表面处理后,纤维在保持原纤维力学性能的同时,与树脂的粘结性得到很大的提高.     

Influence of surface state on moisture sensitivity of carbon fiber and its composite interfacial properties

The influence of surface state on the moisture sensitivity of carbon fiber was analyzed by applying a T800 grade carbon fiber with five different surface conditions, namely, with and without surface oxidation, in the presence or absence of sizing agent. The interfacial properties of their composites in the presence of two epoxy matrices (respectively EP07 and EP10) were also characterized by micro-droplet tests. The overall results show that both oxidized and sizing-coated fibers have higher moisture equilibrium content than that of the pristine unsurface-treated fiber, due to higher amount of activated carbon groups. After moisture absorption of the carbon fibers, almost all the fiber/epoxy systems show decrease in the interfacial shear strength and the unsurface-treated fiber system exhibits the largest decline. Moreover, both interfacial shear strength and interlaminar shear strength of carbon fiber/EP10 composite demonstrate better water resistance performance than that of the carbon fiber/EP07 composite, consistent with DSC results of the two resins.     

Surface adhesive properties of continuous PBO fiber after air-plasma-grafting-epoxy treatment

It was found that air dielectric barrier discharge(DBD) plasma contributed to the grafting of epoxy resin onto continuous PBO fiber surface. This air-plasma-grafting-epoxy method yielded a noticeable enhancement in the interfacial adhesion between PBO fiber and thermoplastic matrix resin, with the interlaminar shear strength of the resulting composites increased by 66.7%. DSC and FTIR analyses were then used to study the curing behavior of epoxy coating on PBO fiber surface, deduce the possible grafting reactions and investigate the grafting mechanism. More importantly, TGA measurement showed that the grafting of epoxy onto PBO fiber had almost no effect on the composite heat resistance, and there was more thermoplastic matrix resin adhering to the fiber surface; the latter could also be clearly found in the SEM photos. Thereby, the air-plasma-grafting-epoxy treatment was proved to be an effective method for the improvement of continuous PBO fiber surface adhesive properties.     

Effect of nano-silica modification on the tensile property of SMA/GF/CF/epoxy super hybrid woven fabric composites

Tensile properties of epoxy casts together with shape memory alloy (SMA), glass (GF) and carbon (CF) woven fabric reinforced epoxy matrix super hybrid composites were investigated, respectively. In order to enhance the mechanical strength of this advanced material, two categories of modifications including matrix blending and fiber surface coating by nano-silica were studied. Scanning electron microscopy (SEM) and fiber pull-out tests were adopted to complement the experimental results, respectively. Experimental results reveal that the toughness of epoxy matrix is enhanced significantly by adding 2wt% nano-silica. The failure mechanism of SMA reinforced hybrid composites is different from that of GF/CF/epoxy composites. Compared with the matrix modification, the fibers modified by coating nano-silica on the surface have better tensile performances. Moreover, the fiber pull-out test results also indicate that composites with fiber surface modification have better interfacial performances. The modification method used in this paper can help to enhance the tensile performance of the mentioned composite materials in real engineering fields.     

Stress singularity near the end of a cylindrical interface and the linear elasticity of push-in tests

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Effect of sizing on the interfacial shear strength of carbon fiber/epoxy resin monofilament composite

The single fiber fragmentation test （SFFT） was used to measure the interracial shear strength （IFSS） of sized and unsized CF800/epoxy resin monofilament composite in order to evaluate the effect of sizing respectively. Besides, the interfacial reinforcing mechanism was explored by analyzing the surface morphology of the carbon fibers, the wettability between the carbon fibers and the epoxy resin, and the chemical characteristics of the fiber surface. Moreover, the effect of sizing on heat and humidity resistance of interface was investigated by aging test. The results show that sizing improves IFSS of CF800/epoxy resin monofilament composite by 59% through increasing the functional groups containing oxygen and through enhancing wettability, while after sizing the heat and humidity resistance of interface is decreased.     

碳纤维上电聚合噻吩对复合材料性能的影响

为了改善碳纤维与树脂基体之间的界面性能,以噻吩为单体,采用循环伏安法对碳纤维进行电化学聚合改性.利用扫描电子显微镜研究了电化学聚合改性前后碳纤维的表面结构变化,采用电脑伺服控制材料试验机测试了碳纤维增强环氧树脂复合材料的力学性能.结果表明,当噻吩浓度为0.4 mol/L时,峰值电流增加幅度最大,电聚合效果最佳.当循环次数达到60次时,碳纤维表面电化学聚合反应完全,碳纤维/环氧树脂复合材料的层间剪切强度可由13.46 MPa增加到23.79 MPa,提高约76.75%.电化学聚合后大量片层状聚噻吩聚合物在碳纤维表面聚集,碳纤维与环氧树脂基体紧密结合,界面性能明显提高.     

最大界面剪切应力的估算与芳纶复合材料界面粘结的表征

研究以估算的最大界面剪切应力，表征芳纶Ｋｅｖｌａｒ４９复合材料的界面粘结。依据Ｇｒｅｓｚｃｚｕｋ模型和单纤维拔出实验数据估算最大界面剪切应力，研究纤维表面处理和基体改性对界面粘结的影响。选用不同活性基团表面的芳纶Ｋｅｖｌａｒ４９和两种耐高温树脂基体组成强粘结界面体系的研究结果表明，实验数据与理论曲线拟合很好。