苯并噁嗪树脂基复合材料的制备及性能表征

本文采用氧等离子体对碳纤维表面进行活化,后用偶联剂接枝的方法对碳纤维表面进行处理。按照GB3357-82和GB3356-82,对复合材料层间剪切强度和弯曲强度进行测试并研究等离子体处理及偶联剂接枝对碳纤维/苯并噁嗪(Polybenzoxazine,PBOZ)复合材料界面粘接性的影响。通过XPS,SEM对碳纤维表面及复合材料断裂面形貌进行测试,分析界面粘接机制。研究表明,氧等离子体处理使碳纤维表面粗糙度和活性含氧基团含量增加,增加了纤维与树脂之间的粘接性;氧等离子体处理后再进行偶联剂接枝,碳纤维表面的含氧官能团增加,浸润性得到改善,提高了碳纤维/PBOZ复合材料界面粘接性能。     

芳纶Ⅲ表面接枝改性的研究

为改进芳纶Ⅲ增强树脂复合材料的层间剪切性能,采用1,6-己二异氰酸酯(HDI)对芳纶Ⅲ进行表面接枝改性处理;通过正交实验方法讨论了不同处理条件对芳纶Ⅲ复合材料层间剪切强度的影响;并对改性前后纤维的表面结构形貌及浸润性能进行表征。结果表明:最佳的接枝改性条件为HDI与催化剂质量比100∶1,反应时间24 h,反应温度20℃;芳纶Ⅲ经表面接枝处理后,纤维表面出现凸棱与凹槽,且接枝了活泼的—NH2基团,纤维与环氧树脂的接触角由处理前的73.6°减小至45.2°,芳纶Ⅲ对树脂的浸润性提高,从而提高其复合材料的层间剪切强度。     

表面处理对Kevlar纤维复合材料界面结合强度的影响

为改善芳纶纤维增强树脂基复合材料的界面结合强度,用化学处理法对Kevlar-29纤维进行表面处理,并用傅里叶变换红外光谱和扫描电镜等方法对表面接枝进行鉴定,用单丝拔出试验表征芳纶纤维增强树脂基复合材料的界面结合强度。实验结果表明,纤维经过表面改性后,在单丝断裂强度降低不大的情况下,界面剪切强度显著提高。     

氨气等离子体接枝环氧涂层改性芳纶Ⅲ表面

采用氨气等离子体接枝环氧涂层工艺对芳纶Ⅲ进行表面改性,采用红外光谱、扫描电镜、原子力显微镜等对改性前后纤维表面的化学组成、形貌、粗糙度、浸润性能进行了研究。结果表明:经氨气等离子体接枝环氧涂层处理后,环氧树脂涂层能够以化学键形式接枝到芳纶Ⅲ表面,同时纤维表面的粗糙度有了明显的增加,浸润性得到显著的改善。     

DBD等离子体改性芳纶表面的动态工艺研究

采用介质阻挡放电(DBD)空气等离子体,选择不同放电强度及处理时间对芳纶表面进行连续动态处理。通过扫描电镜以及光电子能谱仪对处理前后芳纶表面进行表征。结果表明,经DBD等离子体处理后的芳纶表面粗糙度有较大提高,浸润性显著提高,且纤维表面C元素质量分数下降超过5%,0元素质量分数约上升8%;芳纶表面的粗糙度、浸润性及含氧基团含量均随放电强度和处理时间的增加而提高。     

高能辐照对国产芳纶纤维/环氧复合材料界面性能影响

芳纶纤维因其表面惰性、光滑使其与树脂浸润性差,界面结合强度低。以环氧氯丙烷为介质1,采用60Coγ-射线辐照方法对国产芳纶纤维进行表面改性,以界面剪切强度（IFSS）和层间剪切强度（ILSS）表征芳纶/环氧复合材料界面结合性能。结果表明在400kGy辐照剂量下改性效果最好;经高能辐照处理的芳纶纤维表面能升高,并失去了原有的光滑表面,且纤维表面氧含量有大幅度提高,使得纤维表面活性增大。     

低温氨气等离子体对芳纶表面的改性

采用氨气等离子体对芳纶表面进行改性,用X-射线光电子能谱、场发射扫描电子显微镜、力学性能测试等手段对改性前后纤维表面的元素组成、形貌及其拉伸强度进行表征,并进一步通过微脱黏方法分析了等离子体处理条件对芳纶/环氧树脂复合材料界面黏结强度的影响。结果表明:芳纶经表面改性后,其表面极性官能团、表面粗糙度均有所增加,同时与环氧树脂基体的界面黏结强度明显增加。     

芳纶纤维增强树脂基复合材料的界面粘结性能研究

为了改善芳纶纤维增强树脂基复合材料的界面粘结性能,从树脂基体入手,依据相似相容原理和芳纶的结构特点,合成出新型热固性树脂(AFR–T)用作芳纶复合材料的基体,以未经表面处理的芳纶作增强材料,采用热压成型法制备了AFR–T/芳纶纤维复合材料,并通过测定溶度参数、接触角、线膨胀系数、层间剪切强度(ILSS)和横向拉伸强度等方法研究了复合材料的界面粘结性能。结果表明,AFR–T树脂浇注体与芳纶的溶度参数相近,AFR–T树脂溶液在芳纶纸表面的接触角为36.9°,小于环氧树脂(EP)溶液与芳纶纸的接触角(53.2°),说明AFR–T树脂对芳纶的浸润性优于EP;AFR–T/芳纶纤维复合材料的ILSS和横向拉伸强度为73.0 MPa和25.3 MPa,分别比EP/芳纶纤维复合材料提高了25.9%和32.5%,这表明AFR–T树脂与芳纶纤维之间的浸润性和界面粘结性能较好。     

等离子体处理对芳纶性能的影响

芳纶作为增强材料在复合材料中有广泛的应用,其界面性能是影响其复合材料界面粘结性能的重要因素。分别采用H2、空气低温等离子体对芳纶表面进行了处理。研究了等离子体表面改性后芳纶性能的变化。结果表明:经低温等离子体处理后纤维表面张力增大,由46.0mN·m-1增加到63.2mN·m-1;表面极性增强,极性分数由58.0%提高到69.9%,而纤维单丝断裂强度未有明显变化。     

共辐照接枝处理芳纶纤维F3A表面

以环氧氯丙烷为接枝剂,通过高能射线共辐照法对国产芳纶纤维(AFs)进行表面处理,对比了辐照前后芳纶表面形貌、动态接触角、表面自由能及其本体结晶情况变化。用不同辐照剂量下处理的纤维(IAFs-200和IAFs-400)制备了芳纶/环氧(IAFs/ER)复合材料,与未处理纤维相比,共辐照处理的芳纶增强复合材料的界面剪切强度(IFSS)和层间剪切强度(ILSS)分别提高了51.56%和25.79%。辐照处理后纤维表面活性的稳定性良好。     

Improving Interfacial and Compressive Properties of Aramid by Synchronously Grafting and Crosslinking

Improving compressive strength of aramid and its adhesion to resin is of great significance for its application in reinforcing materials. In this study, a novel method for improving interfacial and compressive properties of aramid fiber is presented. α,α′‐Dichloro‐p‐xylene (DCX) is utilized as an external crosslinker to modify aramid fiber containing benzimidazole units during the post swelling process. Chloromethyl groups from DCX can react with benzimidazole moieties of the aramid fiber. The reaction can be regarded as crosslinking inside the fiber and grafting on the surface. By controlling the swelling effect of the solvent during modification, bulk crosslinking degree and surface grafting density can be adjusted. Therefore, intermolecular interaction and surface polarity of the aramid fiber can be improved simultaneously. After modification, the compressive strength of the fiber can be enhanced by nearly 100% and interfacial shear strength increases by 37%, while excellent mechanical properties are maintained. Therefore, comprehensive performance of aramid fiber can be improved significantly by synchronously crosslinking and grafting.     

Interfacial studies on the surface modified aramid fiber reinforced epoxy composites

In this work, solutions of rare earth modifier (RES) and epoxy chloropropane (ECP) grafting modification method were used for the surface treatment of aramid fiber. The effect of chemical treatment on aramid fiber has been studied in a composite system. The surface characteristics of aramid fibers were characterized by Fourier transform infrared spectroscopy (FTIR). The interfacial properties of aramid/epoxy composites were investigated by means of the single fiber pull‐out tests. The mechanical properties of the aramid/epoxy composites were studied by interlaminar shear strength (ILSS). As a result, it was found that RES surface treatment is superior to ECP grafting treatment in promoting the interfacial adhesion between aramid fiber and epoxy matrix, resulting in the improved mechanical properties of the composites. Meanwhile, the tensile strengths of single fibers were almost not affected by RES treatment. This was probably due to the presence of reactive functional groups on the aramid fiber surface, leading to an increment of interfacial binding force between fibers and matrix in a composite system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:4165–4170, 2006     

Effect of rare earth elements surface treatment on tensile properties of aramid fiber‐reinforced epoxy composites

Solutions of rare earth modifier (RES) and epoxy chloropropane (ECP) grafting modification method were used for the surface treatment of aramid fiber. Tensile properties of both the aramid/epoxy composites and single fibers were tested. The effects of RES concentration on tensile properties of aramid/epoxy composites were investigated in detail to explore an optimum amount of rare earth elements in solution for modifying aramid fiber. The fracture surface morphologies of tensile specimens were observed and analyzed with the aid of SEM. The experimental results show that rare earth treatment is superior to ECP grafting treatment in promoting interfacial adhesion between the aramid fiber and epoxy matrix. Meanwhile, the tensile strengths of single fibers were almost not affected by RES treatment. The optimum performance is obtained when the content of rare earth elements is 0.5 wt %. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1037–1041, 2004     

芳纶表面改性技术进展(二)——化学改性方法

对芳纶表面改性的化学方法进行了概述。论述了表面刻蚀技术、表面接枝技术在芳纶表面改性过程中的应用过程、反应原理、改性效果,对化学改性技术的优缺点进行了分析,指出了其进一步的发展趋势。     

RETRACTED ARTICLE: Surface modification of aramid fibers with novel chemical approach

Friedel–Crafts Reaction as a simple and convenient approach to the surface modification of aramid fiber was introduced in this paper. Epoxy chloropropane was chosen as the treatment reagent to modify aramid fibers surface via Graft reaction. After the modification, the interfacial properties of aramid/epoxy composites were investigated by the single fiber pull-out test (SFP), and the mechanical properties of aramid fibers were investigated by the tensile strength test. The results showed that the interfacial shear strength (IFSS) value of aramid/epoxy composites was enhanced by about 50%, and the tensile strength of aramid fibers had no obvious damage. The crystalline state of aramid fibers was determined by X-ray diffraction instrument (XRD), and the results showed that there were not any distinct crystal type varieties. The surface elements of aramid fibers were determined by X-ray photoelectron spectroscopy (XPS), the analysis of which showed that the oxygen/carbon ratio of aramid fiber surface increased obviously. The possible changes of the chemical structure of aramid fibers were investigated via Fourier transform infrared spectrum (FTIR), and the analysis of which showed that the epoxy functional groups were grafted into the molecule structure of aramid fibers. The surface morphology of aramid fibers was analyzed by Scanning electron microscope (SEM), and the SEM results showed that the physical structure of aramid fibers was not etched or damaged obviously. The surface energy of aramid fibers was investigated via the dynamic capillary method, and the results showed that the surface energy was enhanced by 31.5%, and then the wettability degree of aramid fiber surface was enhanced obviously too. All of the results indicated that this novel chemical modification approach not only can improve the interfacial bonding strength of aramid/epoxy composites remarkably, but also have no negative influence on the intrinsic tensile strength of aramid fibers.     

Adhesive joints between carbon fiber and aluminum foam reinforced by surface‐treated aramid fibers

Short aramid fibers have been successfully used to reinforce the interface adhesive property between carbon fiber/epoxy composites and aluminum foam, and to form aramid‐fiber “composite adhesive joints.” In this study, to further improve the reinforcing effect of the aramid‐fiber‐reinforced adhesive joints, aramid fibers were ultrasonic treated to conduct different surface conditions. Critical energy release rate of the carbon fiber/aluminum foam sandwich beams with as‐received and treated interfacial aramid fibers were measured to study the influence of the surface treatment on aramid fibers. It was found that reinforcements in critical energy release rate were achieved for all samples with treated aramid fiber as measured under double cantilever beam condition. The interfacial characteristics of the short aramid fibers with different surface condition were investigated and discussed based on scanning electron microscopy observations. It is suggested that advanced bonding between aramid fibers and epoxy resin was conducted after surface treatment, and more energy was therefore absorbed through fiber bridging during crack opening and extension process. POLYM. COMPOS., 36:192–197, 2015. © 2014 Society of Plastics Engineers     

空气等离子体处理芳纶纤维及其与天然橡胶/乳聚丁苯橡胶的黏合性能

考察了空气等离子体处理对芳纶纤维表面结构形态的影响,研究了空气等离子体和间苯二酚-甲醛-胶乳(RFL)浸胶处理芳纶纤维与天然橡胶(NR)/乳聚丁苯橡胶(ESBR)的黏合性能,并对经处理的芳纶纤维与NR/ESBR体系的界面层作了动态力学分析。结果表明,芳纶纤维经空气等离子体处理后,表面粗糙度增大,表面积增加,结晶度减小,但处理功率过大、处理时间过长时,芳纶纤维的表面又变得比较光滑、结晶度又呈增大趋势。随着等离子体处理时间的延长,芳纶纤维与NR/ESBR的黏合性能增强,但处理时间过长时,芳纶纤维与NR/ESBR的黏合性能下降;等离子体处理芳纶纤维经RFL进一步浸胶处理后,芳纶纤维与NR/ESBR的黏合性能大幅度提高。芳纶纤维与NR/ESBR的界面存在介于高模量芳纶纤维和低模量橡胶之间的过渡层。