电晕处理对超高分子量聚乙烯纤维表面性能的影响

对超高分子量聚乙烯（UHMWPE）纤维表面进行了电晕处理，用XPS，FT-IR和SEM研究了处理前后纤维表面化学结构及物理结构的变化，通过单丝拔出试验和短梁剪切试验评价了UHMWPE纤维与树脂基体的微宏观界面粘接性能,结果表明：经电晕处理后，UHMWPE纤维表面含氧量增多，含氧基团数量与种类增加，表面浸润性得到改善，纤维与基体的界面粘结强度（Ts）提高幅度可达535％，短梁剪切强度TNOL提高了40％以上．     

氩气低温等离子体处理对PBO纤维的表面改性

采用低温等离子体表面处理技术对聚苯撑苯并二口恶唑(PBO)纤维表面进行改性.选用氩气作为处理气氛,研究了气压、功率和处理时间等参数对纤维表面性质的影响.采用FT-IR和SEM等方法对处理前后纤维表面化学结构及形态结构进行了表征,并通过单丝拔出试验测定了改性前后PBO纤维与环氧树脂基体的界面剪切强度(IFSS),对纤维与树脂的界面粘结性进行了初步评价.同时,采用液滴形状法对纤维表面亲水性进行了表征.通过研究发现,经低温氩气等离子处理后,PBO纤维表面亲水性增强,PBO纤维/环氧树脂的IFSS较未处理样品提高了42%.     

PBO纤维表面超声化学处理工艺及作用机理

研究了多聚磷酸无水乙醇溶液和超声波附加作用处理聚对苯撑苯并双口恶唑(PBO)纤维表面的工艺。利用扫描电镜和纤维电子强力仪等评价了表面处理后PBO纤维的表面形貌、拉伸强度以及与环氧树脂的界面结合性能等,探讨了PBO纤维超声化学表面作用机理。结果表明,当多聚磷酸与无水乙醇体积比为1∶1、超声设备功率54W、反应时间4min时,PBO纤维的表面处理均匀,与原丝相比,单丝拉伸强度只降低了5.7%,而单丝拔出强度则提高了67.2%。超声波的空化作用导致溶液中多聚磷酸分子分散均匀性提高、羟基自由基含量增加,以及纤维表面粗糙度提高,是PBO纤维表面处理质量改善的主要原因。     

高性能有机纤维单丝复合体系界面粘结性能实验研究

采用单丝复合体系多次断裂法,通过对纤维单丝断点数的统计及其断点形貌的分析,考察了PBO纤维、芳纶Twaron纤维、超高分子量聚乙烯纤维(UHMWPE)3种高性能有机纤维与韧性环氧基体的界面剪切强度;并对比考察了界面剪切强度与对应复合材料单向板层间剪切强度之间的关系;结合XPS、SEM等手段分析了有机纤维表面物理化学特性对界面剪切强度的影响。结果表明,Twaron/环氧的界面剪切强度高于PBO/环氧,UHMWPE/环氧的界面粘结弱,该方法不能测试;上述体系界面剪切强度与对应的复合材料单向板层间剪切强度变化趋势是一致的;表面化学活性高的纤维对应的界面剪切强度高。     

氧气DBD等离子体处理PBO纤维表面及其对双马树脂基复合材料界面性能的影响

采用氧气介质阻挡放电(DBD)等离子体处理PBO纤维表面,用以改善PBO纤维与双马来酰亚胺(BMI)树脂之间的界面粘结性能。结果表明,用氧气等离子体处理PBO纤维能大幅度提高PBO/BMI复合材料的层间剪切强度(ILSS)值,最佳处理条件为功率30 W/m³、时间24 s,ILSS值从43.9 MPa提高到62.0 MPa。经过氧气DBD等离子体处理的PBO纤维其表面的氧含量明显提高,氮含量变化不大,甚至在过度处理时降低;官能团-O-C=O基团的含量从0提高到3.16%,-C-O-的含量也明显提高;在氧气DBD等离子体处理后的PBO纤维表面产生大量凹凸不平和沟壑,使纤维表面的粗糙度提高。而表面氧含量的提高和表面形貌与粗糙度的变化,是PBO/BMI复合材料ILSS值提高的重要原因。单丝拉伸实验结果表明,适当的DBD等离子体处理不会对PBO纤维表面产生不良影响,不影响其在复合材料中的作用。     

羟基基团对PBO纤维表面性能及界面粘结性能的影响

以2,5-二羟基对苯二甲酸(DHTA)为改性单体,采用化学共聚改性的方法,合成了大分子链上含有羟基基团的聚对苯撑苯并二噁唑(PBO)与DHTA 的共聚物(DHPBO),并通过液晶纺丝技术得到了DHPBO 纤维。利用FTIR、接触角等分析手段对其化学结构和纤维表面性能进行了表征,并通过微脱粘实验和SEM评价了DHPBO纤维与环氧树脂基体的界面剪切强度。结果表明：50 mol%DHTA的加入使水在PBO纤维表面的接触角由71.4° 减小到50.7°,乙醇在PBO纤维表面的接触角由37.2° 减小到27.4°;当DHTA含量为20 mol%时,DHPBO纤维的表面自由能增加到43.96 mJ/m2,比PBO纤维提高了23.83%。当 DHTA含量为10 mol%时,DHPBO纤维与环氧树脂的界面剪切强度为18. 87 MPa,比PBO纤维与环氧树脂的界面剪切强度提高了92.55%。     

CaCl1和多巴胺处理对芳纶纤维表面结构与性能的影响

采用氯化钙(CaCl2)乙醇溶液和多巴胺水溶液浸渍法对芳纶纤维表面进行改性处理,对改性后芳纶纤维表面的化学结构、微观形貌、表面粗糙度、单丝拉伸强度和芳纶纤维/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,采用CaCl2乙醇溶液处理芳纶纤维后,芳纶纤维表面有刻蚀出的沟槽,表面粗糙度增大,芳纶纤维/环氧树脂复合材料的层间剪切强度明显提高,同时由于纤维结构受到破坏,单丝拉伸强度下降了11.12％;采用多巴胺水溶液处理时,芳纶纤维表面沉积了聚多巴胺涂层,表面粗糙度增大,芳纶纤维/环氧树脂复合材料的层间剪切强度进一步提高,纤维结构几乎不受影响,单丝拉伸强度降幅较小;采用CaCl2乙醇溶液和多巴胺水溶液先后处理芳纶纤维后,纤维表面的聚多巴胺涂层更致密,复合材料的层间剪切强度达到最大值,同时改性后的纤维具有一定的抗紫外性能,此方法改性效果最优.     

CaCl_2和多巴胺处理对芳纶纤维表面结构与性能的影响

采用氯化钙(CaCl_2)乙醇溶液和多巴胺水溶液浸渍法对芳纶纤维表面进行改性处理,对改性后芳纶纤维表面的化学结构、微观形貌、表面粗糙度、单丝拉伸强度和芳纶纤维/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,采用CaCl_2乙醇溶液处理芳纶纤维后,芳纶纤维表面有刻蚀出的沟槽,表面粗糙度增大,芳纶纤维/环氧树脂复合材料的层间剪切强度明显提高,同时由于纤维结构受到破坏,单丝拉伸强度下降了11.12%;采用多巴胺水溶液处理时,芳纶纤维表面沉积了聚多巴胺涂层,表面粗糙度增大,芳纶纤维/环氧树脂复合材料的层间剪切强度进一步提高,纤维结构几乎不受影响,单丝拉伸强度降幅较小;采用CaCl_2乙醇溶液和多巴胺水溶液先后处理芳纶纤维后,纤维表面的聚多巴胺涂层更致密,复合材料的层间剪切强度达到最大值,同时改性后的纤维具有一定的抗紫外性能,此方法改性效果最优。     

芳纶纤维的磷酸表面处理及其树脂基复合材料界面性能

采取不同浓度的磷酸水溶液对芳纶纤维进行表面处理, 并对不同处理条件下芳纶纤维的单丝强度、表面性质及其环氧树脂复合材料的界面性能进行了分析和测试。结果表明: 20 wt %磷酸溶液处理的芳纶纤维, 纤维表面含氧官能团含量最高; 继续提高磷酸溶液的浓度, 含氧官能团含量下降, 纤维表面趋于平整, 单丝强度上升。用20 wt %磷酸溶液处理芳纶纤维, 纤维/ 环氧树脂基复合材料的层间剪切强度达到62 MPa , 界面剪切强度提高18 % , 是一种简单有效的表面处理方法。纤维表面粗糙度和纤维表面含氧官能团的数量是影响芳纶纤维/ 环氧树脂复合材料界面结合性能的关键因素。      

环氧改性水性聚氨酯上浆剂对碳纤维/氰酸酯树脂复合材料界面性能的影响

使用自行合成的环氧改性水性聚氨酯(EWPU)上浆剂对碳纤维进行表面处理,主要研究了EWPU上浆剂对碳纤维表面及碳纤维/氰酸酯树脂复合材料界面性能的影响。采用扫描电镜(SEM)、傅里叶红外光谱(FTIR)、X射线光电子能谱(XPS)和静态接触角等表征方法对比研究了二次上浆处理前碳纤维(CF)和处理后碳纤维(MCF)的表面形貌、表面化学元素组成和浸润性的变化,并通过单纤维破碎实验和短梁剪切法,研究了EWPU上浆剂对碳纤维/氰酸酯树脂复合材料界面力学性能的影响。结果表明,经EWPU上浆处理后碳纤维表面O/C值增加了39.13%,表面活性官能团的含量增加了14.97%,碳纤维与树脂的初始和稳态接触角分别减小了19.41%和20.59%,碳纤维/氰酸酯树脂复合材料的单丝界面剪切强度和层间剪切强度分别增加了13.42%和14.29%。     

PBO纤维表面空气冷等离子体改性

采用等离子体处理方法对PBO(聚对苯撑苯并二 口 恶 唑)纤维表面进行改性。用XPS和AFM测试分析等离子处理时间对PBO纤维表面组成和表面形貌的影响规律;首次采用浸润性测试和IR测试分析等离子体处理前后纤维浸润性和表面官能团的变化。用Microbond测试方法表征了纤维与树脂基体的界面剪切强度,并用SEM观察微复合材料破坏形貌。结果表明:等离子体处理后纤维浸润性得到改善,纤维表面苯环上引入了很多羟基。等离子体处理最佳条件下(170 W,10 min),纤维表面粗糙度最大,纤维表面O元素含量最大, O/C比率提高了50.5 %, IFSS值提高了64.7 %。     

PBO纤维表面等离子体接枝改性研究

采用等离子体接枝改性方法对PBO纤维表面进行改性研究，利用AFM分析改性前后纤维表面的形貌变化，测试了改性前后纤维表面浸润性变化，并采用Microbond方法表征了纤维与树脂基体的界面IFSS。结果表明：等离子体接枝后纤维表面引入了活性基团，纤维浸润性改善；在100W、10min接枝条件下IFSS提高了75％。     

Hierarchical poly(p-phenylene benzobisoxazole)/graphene oxide reinforcement with multifunctional and biomimic middle layer

A new hierarchical reinforcement developed by coating biomimic polydopamine (PDA) on the surface of poly(p-phenylene benzobisoxazole) (PBO) fibers, which served as a platform for the graphene oxide (GO) grafting, using branched polyethyleneimine (b-PEI) as a bridging agent. The surface morphologies and chemical structures of PBO fibers were characterized for confirming the formation of covalent bond between GO and PBO fibers. The surface roughness (R_a) and wettability of the obtained fibers, denoted as PBO@PDA-PEI-GO, were obviously increased in comparison with those of untreated one. The reinforcement offered a 68.8% enhancement in the interfacial shear strength (IFSS) without degrading the base fiber. The PDA layer on the PBO fiber surface led to improved UV resistance. The hydrothermal aging resistance of PBO/epoxy composite was also greatly improved. This biomimic surface modification approach is facile to prepare, highly efficient to enhance interface, adaptable to all high-performance fibers, and meaningful in multifunctional applications.     

Interfacial failure in poly(p-phenylene benzobisoxazole) (PBO)/epoxy single fibre pull-out specimens

The pull-out behaviour of poly(p-phenylene benzobisoxazole) fibres from an epoxy resin has been shown to follow that predicted by the elastic stress transfer shear-lag model at low applied strains, but at higher matrix strains a partial debonding model was more suitable. Debonding of the fibre/matrix interface led to interfacial failure where only friction resisted fibre extraction. Raman spectroscopy was able to quantify this level of friction and together with in situ optical microscopy proved an excellent method for the close monitoring of the frictional pull-out process. The effect of fibre surface treatment was also studied. The interfacial shear stress values from the heat-treated and corona-treated fibres showed only small differences. The failure processes were examined further using scanning electron microscopy and clean fibre pull-out was observed with the heat-treated fibre whereas fracture of the free fibre occurred with the corona-treated fibre.     

The uniform treatment of carbon fiber surface in three-directional orthogonal fabric by oxygen-plasma

An oxygen-plasma treatment of carbon fibre surface in three-directional orthogonal fabric preforms was investigated in this paper. The effects of this treatment on the surface wettability and chemical components of the fibres in both the interior and surface regions of the fabrics were analyzed by using dynamic capillary method and X-ray photoelectron spectroscopy (XPS), respectively. A microdebonding method was employed to determine the uniformity of interfacial shear strength between the fibre and matrix in different regions of the carbon fabric-phenolic composites, and the flexural strength was also tested to evaluate the effects of the treatment. The results indicated that, the oxygen-plasma significantly improved the interfacial adhesion by etching, activating the surface of the fibres, and generating the oxygenic functional groups. However, for the fibres in different regions of the fabric, the degrees of the treatment were different, and a longer treatment time was needed to get the relative uniform effect through the fabric. Meanwhile, the loss of tensile property of the fibre due to treatment was investigated and found to be small in the range of useful treatments.     

Characterization and micromechanical testing of the interphase of aramid-reinforced epoxy composites

The properties of the interphase between Twaron^® aramid fibres and polymer matrix systems can be optimized by a surface treatment process of the fibres. The relation between this surface treatment, the resulting chemical and physical surface structure, as measured with XPS, IGC and SFM, and the adhesion strength in fibre–epoxy systems, as measured with Raman spectroscopy and single-filament pull-out experiments, has been established and related to the macromechanical data of real composites. The concept of local bond strength was used and the fibre–epoxy failure mechanism investigated.     

Influence of fibre surface oxidation treatment on mechanical interfacial properties of carbon fibre/ polyarylacetylene composites

Abstract

In the present work, the mechanical interfacial properties of carbon fibre (CF) reinforced polyarylacetylene (PAA) resin composites were modified through the surface oxidation treatment of carbon fibres by ozone. Both X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy showed that oxidation treatment could increase the amount of elemental oxygen on the fibre surface markedly by introducing more oxygen groups. Atomic force microscopy (AFM) images indicated that weak surface regions of fibres had been etched and removed, and the degree of fibre surface roughness was increased. The interlaminar shear strength (ILSS) and the interfacial shear strength (IFSS) of CF/PAA composites were both improved notably (no less than 50%). It could be concluded that an improvement of fibre surface chemical activity, better wettability of resin on the carbon fibre surface, and stronger mechanical joining between fibres and resin all resulted in the modification of interfacial properties of carbon fibre reinforced PAA composites. The influences of temperature, ozone concentration, and treatment time on the oxidation results were studied, and optimal treatment parameters determined.