亚临界水介质回收酸酐固化环氧树脂/碳纤维复合材料

研究了不同添加剂对碳纤维增强酸酐固化环氧树脂复合材料在亚临界水中降解的影响,通过IR、GC-MS等分析,确定了环氧树脂的分解机理主要为酯键的断裂。 结果表明,KOH与苯酚对酸酐固化环氧树脂的分解没有协同效应,碱性物质更有利于酯键的断裂。 甲基四氢邻苯二甲酸酐固化的环氧树脂增强碳纤维复合材料在反应温度为250 ℃、反应时间为60 min、KOH浓度为0.2 mol/L时可完全分解,回收碳纤维的拉伸强度和表面形貌未受影响。     

氨基硅油改性碳纤维/环氧树脂复合材料的耐老化性能

通过在复合树脂基体中引入氨基硅油进行改性,制备了不同氨基硅油含量的碳纤维/环氧树脂复合材料,在湿热环境下进行老化实验后,通过动态热机械分析(DMA)、热重分析(TGA)、拉伸性能测试、扫描电镜(SEM)及接触角测定等方法研究氨基硅油对于碳纤维/环氧树脂复合材料热力学性能、力学强度保持率和耐水性能的改善效果。实验结果表明,经老化实验后含氨基硅油材料的抗拉强度保持率最高提升了13.23%。当氨基硅油含量为8 wt%时,复合材料表面接触角均值大于90~o。氨基硅油对环氧树脂基体的改性可改善碳纤维/环氧树脂复合材料的耐湿热老化性能。     

高亲水性环氧树脂的制备及对碳纤维的表面处理

在三乙胺催化下,以己二酸和环氧树脂制备了己二酸改性环氧树脂(AAEP),通过考察反应温度等因素对己二酸转化率和AAEP环氧值的影响,得到了AAEP合成的最佳条件.用傅里叶变换红外光谱和核磁共振对AAEP进行了表征.用KOH中和AAEP得到己二酸改性环氧树脂钾盐(AAEPK),测试了AAEPK乳液的性质和AAEPK处理后碳纤维的分散性,并通过场发射扫描电子显微镜和X射线光电子能谱对碳纤维的表面形貌和基团进行了研究.结果表明,AAEPK具有高亲水性,适用于碳纤维处理剂,当AAEPK的浓度和吸附量分别为1.0%(质量分数)和3.0 mg/g时,处理剂可在纤维表面均匀分布,使得碳纤维在树脂基体中的分散性得到改善.研究了处理剂对碳纤维/环氧树脂复合材料弯曲和剪切性能的影响,发现处理后碳纤维短丝/环氧树脂复合材料的弯曲强度和碳纤维布/环氧树脂复合材料的层间剪切强度较未处理的试样分别增加了168%和113%,说明AAEPK处理后碳纤维在基体中分散性和黏结性的提高是碳纤维/环氧树脂复合材料力学性能提高的主要原因.     

氧化石墨烯接枝碳纤维新型增强体的制备与表征

利用“Grafting-to”化学修饰法制备氧化石墨烯接枝国产碳纤维新型增强体。利用红外光谱、X射线光电子能谱和原子力显微镜对样品的官能团和表面形貌进行表征;利用接触角测量、单丝拉伸方法研究了接枝前后纤维单丝的润湿性能及拉伸强度,并通过微脱粘法分析了其复合材料的界面剪切强度。结果表明：氧化石墨烯的接枝修饰使国产碳纤维表面粗糙度提高了166%,表面能提高了46.3%,拉伸强度提高了7.8%,复合材料的界面剪切强度提高了111.7%。     

碳纤维中的单层石墨物相及其对力学性能的影响

依据碳纤维中各种物相的X射线衍射特性, 确认PAN基碳纤维中除了乱层石墨微晶外, 还存在大量的单层六元环C原子层面物相, 建立起两种非完整结晶物相的定量分析方法. 实验结果表明, 随着退火温度由1350 ℃上升到2400 ℃, Tx-3高强型碳纤维中的单层石墨含量由59.6%下降到34.8%, 乱层石墨含量由40.4%上升为65.2%. 与此同时, 碳纤维的拉伸强度则由3.65 GPa下降到2.05 GPa, 而延伸率也由1.04%下降到0.58%. 并对PAN基碳纤维中单层石墨对其力学性能的影响也进行了初步的探讨.     

全钒液流电池用导电高分子材料集流体的研究

以炭黑、石墨、碳纤维等炭系与基体树脂复合改性得到体积电阻率小于0.1的导电高分子材料.研究了不同复合体系及不同配方的复合材料的导电性能,其中尤以SIS/PP体系中碳纤维占填料量32.5%的材料导电率高、力学性能和加工性能良好,并与石墨毡有较好的粘接性.选用该体系作为钒电池集流板,考察了电池性能,研究结果表明,导电高分子材料可以作为钒电池集流体材料,并在钒电池中具有良好的应用前景.     

高性能可回收环氧树脂及其复合材料的制备与性能研究

采用戊二酸酐为固化剂,乙酰丙酮锌为催化剂制备了一种综合性能优异的高性能可回收环氧树脂.系统研究了固化剂及催化剂含量对树脂结构、热学及动态性能的影响,实现了树脂组成的优化设计.基于酯交换反应的热可逆性,制备的vitrimer树脂通过物理热压方法可实现良好回收,力学强度保持率可达80%.采用RTM工艺制备的碳纤维织物增强vitrimer树脂复合材料表现出与传统热固性树脂基复合材料相当的力学性能,并且通过醇类溶剂热降解树脂的方法,可实现复合材料中碳纤维的高效无损回收,回收率近100%.     

环氧树脂在碳纤维表面的浸润行为

利用场发射环境扫描电境(FESEM)测定了室温下环氧树脂在单纤维表面的接触角,观测并计算了环氧树脂液滴在单根碳纤维表面的接触角随温度的变化,结果表明接触角随温度升高明显降低,说明升高温度有利于改善环氧树脂对碳纤维的浸润性能.用液滴形状分析仪(DSA)在垂直和平行于纤维排列方向上观测了不同温度下单向排列碳纤维集束表面环氧树脂的铺展过程,发现在不同方向上观测到的接触角差别较大,其中垂直于纤维排列方向上观测到的接触角随温度的变化与环氧树脂在单根碳纤维表面的接触角变化基本一致,说明环氧树脂在平行于纤维束方向的接触角真正代表其浸润性能.     

PIP法制备Cf/SiC复合材料过程中碳纤维的化学损伤

对先驱体聚碳硅烷浸渍裂解工艺(PIP)制备Cf/SiC复合材料过程中碳纤维损伤严重的问题, 系统地分析了在Cf/SiC复合材料制备过程中先驱体裂解对碳纤维的化学损伤. 研究结果表明, PIP工艺中碳纤维的化学损伤包括界面反应和基体向碳纤维内部的扩散反应. 其中聚碳硅烷(PCS)中的活性基团和碳纤维的化学反应并不严重, 而微量的氧气和杂质对碳纤维的化学损伤影响很大; 基体中硅等元素可向碳纤维内部扩散, 随着高温处理时间的延长而加深, 并形成脆性的界面层, 使碳纤维截面积减小. 在第一周期浸渍裂解过程中, 先驱体对碳纤维的化学损伤很少, 在后续周期中, 随着基体致密度的提高, 碳纤维的化学损伤有所增加.      

碳源对鱼骨式纳米碳纤维及其负载的钯催化剂性能的影响

分别以甲烷、一氧化碳和乙烯为碳源合成了3种鱼骨式结构的纳米碳纤维(FCNF-C1,FCNF-CO和FCNF-C2),并作为载体制备了3种钯催化剂(Pd0.5%),考察了在对苯二甲酸加氢精制中的催化活性,通过N2吸附-脱附、X射线衍射、程序升温脱附、电子透射显微镜及CO化学吸附等方法对载体以及催化剂的结构进行了表征.结果表明,从不同碳源合成的纳米碳纤维(CNF)具有相似的直径和鱼骨式石墨层排列方式,但其物理化学性能差异较大,其中CO作为碳源得到的CNF具有最大的比表面积,最高的石墨化程度和最多的表面含氧基团;不同碳源的鱼骨式CNF负载的钯催化剂的活性为:Pd/FCNF-CO>Pd/FCNF-C1>Pd/FCNF-C2,与Pd分散度的顺序一致.CNF的织构、晶体结构和表面化学等协同载体效应,决定了Pd金属在CNF上的分散状态以及催化性能,而CNF的石墨层排列方式对其影响很小.     

Chemical recycling of carbon fibre reinforced epoxy resin composites in subcritical water: Synergistic effect of phenol and KOH on the decomposition efficiency

The combination of phenol and potassium hydroxide (KOH) was used to chemically recycle carbon fibre reinforced epoxy resin cured with 4,4′-diaminodiphenylmethane in subcritical water. This combination had a synergistic effect on decomposing this kind of epoxy resin. The main decomposition products from the epoxy resin were identified by means of GC-MS, and a possible free-radical reaction mechanism for the decomposition of epoxy resin is proposed. The recovered carbon fibres were characterized using single fibre tensile tests, scanning electron microscopy and X-ray photoelectron spectroscopy. Compared to virgin carbon fibres after sizing removal, the surface compositions of the recovered carbon fibres had little change and the tensile strength of the recovered carbon fibres was well retained.     

Recyclable carbon fiber‐reinforced plastics (CFRP) containing degradable acetal linkages: Synthesis,properties, and chemical recycling

Two epoxy resins containing degradable acetal linkages were synthesized by the reaction of cresol novolak‐type phenolic resin (CN) with vinyl ethers containing a glycidyl group [cyclohexane dimethanol vinyl glycidyl ether (CHDMVG) and 4‐vinyloxybutyl glycidyl ether (VBGE). Carbon fiber‐reinforced plastics (CFRPs) were prepared by heating laminated prepreg sheets with CN‐CHDMVG resin (derived from CN and CHDMVG) and CN‐VBGE resin (derived from CN and VBGE), in which carbon fibers are impregnated with epoxy resins containing curing agents [dicyandiamide (DICY)] and curing accelerator [3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU)]. CN‐CHDMVG‐based CFRPs and CN‐VBGE‐based CFRPs exhibited almost the same tensile strength as the conventional bisphenol‐A‐based CFRPs. CN‐CHDMVG‐based CFRPs and CN‐VBGE‐based CFRPs underwent smooth breakdown with the treatment of hydrochloric acid in tetrahydrofuran at room temperature for 24 h to regenerate strands of carbon fibers. The surface conditions of the recovered carbon fibers had little changes during degradation and recovery processes on the basis of scanning electron microscopy (SEM) and X‐ray photoelectron spectroscopy (XPS). The recovered carbon fibers exhibited almost the same tensile strength as virgin carbon fibers and hence would be reused for the production of CFRPs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1052–1059     

Effect of carbon fiber surface functionality on the moisture absorption behavior of carbon fiber/epoxy resin composites

Polyacrylonitrile (PAN)‐based carbon fibers were electrochemically oxidized in aqueous ammonium bicarbonate with increasing current density. The electrochemical treatment led to significant changes of surface physical properties and chemical structures. The oxidized fibers showed much cleaner surfaces and increased levels of oxygen functionalities. However, it was found that there was no correlation between surface roughness and the fiber/resin bond strength, i.e. mechanical interlocking did not play a major role in fiber/resin adhesion. Increases in surface chemical functionality resulted in improved fiber/resin bonding and increased interlaminar shear strength (ILSS) of carbon fiber reinforced epoxy composites. The relationship between fiber surface functionality and the hydrothermal aging behavior of carbon fiber/epoxy composites was investigated. The existence of free volume resulted from poor wetting of carbon fibers by the epoxy matrix and the interfacial chemical structure were the governing factors in the moisture absorption process of carbon fiber/epoxy composites. Copyright © 2016 John Wiley & Sons, Ltd.     

环氧氯丙烷修饰的对位和间位芳纶涂覆剂研究

制备了具有环氧丙基侧链的对位芳纶(PPTA-ECH)和间位芳纶(PMIA-ECH),并将其用做对位芳纶(PPTA)织物/环氧树脂复合材料中PPTA织物的涂覆剂。采用场发射扫描电子显微镜(FE-SEM)及XPS等方法对PPTA织物表面的PPTA-ECH涂层结构进行了表征。考察了PPTA-ECH和PMIA-ECH涂覆的PPTA织物/环氧树脂复合材料的层间剪切强度和面内剪切强度,并与未经涂覆的PPTA织物复合材料的性能作比较。结果表明,PPTA-ECH和PMIA-ECH可显著改善PPTA织物和环氧树脂之间的界面性能。涂覆了PPTA-ECH及PMIA-ECH的PPTA织物/环氧树脂复合材料的层间剪切强度(ILSS)比未经涂覆的复合材料分别提高了26.20%和14.76%,面内剪切强度(ISS)分别提高了26.98%和11.86%。由于PPTA-ECH对PPTA纤维具有更强的亲和能力,因此PPTA-ECH在层间剪切强度和面内剪切强度方面的增强效果均优于PMIA-ECH。对PPTA-ECH在PPTA纤维表面铺展与吸附及对复合材料的增强机理也进行了初步探讨。作为新型涂覆剂,PPTA-ECH在对位芳纶复合材料的开发应用方面具有潜在的应用前景。     

The crosslinking of epoxy resins at interfaces. III. At a carbonized polyacrylonitrile surface

The crosslinking chemistry of an anhydride-cured epoxy resin, in the first 200–400 nm adjacent to a carbonized polyacrylonitrile (PAN) surface (a model for the surface of a carbon fiber), is significantly affected by the humidity history of that surface. Prior humid aging of the carbonized PAN surface increases the subsequent rate of consumption of anhydride curing agent, and decreases the yield of ester crosslinked products. The crosslinking chemistry of an amine-cured epoxy resin appears unchanged by the presence of the carbonized surface. Dynamic mechanical analysis (DMA) of unidirectional composites made from carbon fibers and the above epoxy resin matrices shows that the damping characteristics of composites made with an epoxy–anhydride matrix are sensitive to the preconditioning history of the carbon fibers, while composites made with an epoxy–amine matrix are unaffected by the preconditioning history of the fibers. Partial removal of the carbon fiber surface coating by dichloromethane extraction does not change the sensitivity of the composites to fiber preconditioning history. These results are rationalized on the basis of the effect moisture adsorbed by the carbonized PAN and by the carbon fiber has on the epoxy resin crosslinking processes.     

聚苯氧基磷酸联苯二酚酯/聚磷酸铵膨胀阻燃剂对环氧树脂阻燃性能影响研究

以聚苯氧基磷酸联苯二酚酯(PBPP)与聚磷酸铵(APP)组成复合阻燃剂,对环氧树脂(EP)进行阻燃改性.通过氧指数(LOI)、垂直燃烧(UL-94)、热失重(TGA)、锥形量热(CONE)和扫描电镜(SEM)等方法研究改性环氧树脂的阻燃性能和阻燃机理.结果表明,PBPP/APP体系对EP具有较好的阻燃性能,阻燃剂添加量为10%时能使环氧树脂的氧指数提高到29.6%,垂直燃烧等级达到UL94 V-0级,残炭量大大增加;平均热释放速率下降45.7%,热释放速率峰值下降51.0%,有效燃烧热平均值下降21.1%;TGA、CONE、SEM等综合分析显示了PBPP/APP改性后的环氧树脂比纯环氧树脂具有更高的热稳定性,燃烧后能够形成连续、致密、封闭、坚硬的焦化炭层,在聚合物表面产生有效覆盖、隔绝了氧气,改善了环氧树脂的燃烧性能.     

The crosslinking of epoxy resins at interfaces. V. Amine-cured resins at carbon and graphite surfaces

The effects of carbon blacks, chopped carbon fibers, and crushed carbon fibers on the crosslinking chemistry of a diglycidyl epoxy resin/m-phenylenediamine system were examined by infrared (IR) spectroscopy and differential scanning calorimetry (DSC). The carbon and graphite surfaces were given oxidizing and reducing treatment to simulate the surface treatment of carbon fibers used in the manufacture of composites. The oxidized carbon surfaces initially accelerated epoxy–amine reactions but inhibited the later stages of the reaction such that the final extent of cure was reduced. The oxidized carbons also preferentially adsorbed the amine curing agent, resulting in a stoichiometric imbalance at the interface.     

Degradable and chemically recyclable epoxy resins containing acetal linkages: Synthesis,properties, and application for carbon fiber‐reinforced plastics

Four sorts of epoxy resins containing degradable acetal linkages were synthesized by the reaction of bisphenol A (BA) or cresol novolak (CN) resin with vinyl ethers containing a glycidyl group [4‐vinlyoxybutyl glycidyl ether (VBGE) and cyclohexane dimethanol vinyl glycidyl ether (CHDMVG)] and cured with known typical amine‐curing agents. The thermal and mechanical properties of the cured resins were investigated. Among the four cured epoxy resins, the CN‐CHDMVG resin (derived from CN and CHDMVE) exhibited relatively high glass transition temperature (T_g = ca. 110 °C). The treatment of these cured epoxy resins with aqueous HCl in tetrahydrofuran (THF) at room temperature for 12 h generated BA and CN as degradation main products in high yield. Carbon fiber‐reinforced plastics (CFRPs) were prepared by heating the laminated prepreg sheets with BA‐CHDMVG (derived from BA and CHDMVE) and CN‐CHDMVG, in which strands of carbon fibers are impregnated with the epoxy resins containing conventional curing agents and curing accelerators. The obtained CFRPs showed good appearance and underwent smooth breakdown with the aqueous acid treatment in THF at room temperature for 24 h to produce strands of carbon fiber without damaging their surface conditions and tensile strength. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012