电泳沉积氧化石墨烯的碳纤维表面改性及其增强环氧树脂复合材料界面性能

采用超声辅助电泳沉积法,以异丙醇作为溶剂,在连续碳纤维(CF)表面沉积一层氧化石墨烯(GO),对CF表面进行改性。再经200℃高温处理来增强(GO)与CF之间的黏合性,从而增加CF/环氧树脂(EP)复合材料的界面结合强度。利用SEM和AFM对改性前后CF的表面形貌及微观结构变化进行了表征,通过XPS对改性前后CF表面官能团的变化进行了检测。结果表明,在CF表面沉积GO并经200℃处理后,有效地部分还原了GO(RGO),填补或桥联了CF表面缺陷,使改性后CF的拉伸强度提高了34.58%。同时,高温处理使RGO与CF之间生成牢固的化学键,从而提高了RGO与CF之间的结合强度,最终使RGO-CF/EP复合材料的界面剪切强度(IFSS)提高了69.9%。      

氧化石墨烯改性碳纤维/环氧树脂复合材料的湿热性能及微观形貌

采用湿法预浸技术和模压工艺制备了氧化石墨烯(GO)改性碳纤维/环氧树脂(CF/EP)复合材料,研究了 GO在室温干态及湿热处理后对CF/EP复合材料动态热力学性能和层间剪切性能的影响,并通过微观形貌分析了复合材料的改性机制.结果表明,当GO添加量分别为0.5％和0.8％时,GO-CF/EP复合材料的玻璃化转变温度(Tg...     

氧化石墨烯改性不同表面性质的碳纤维/环氧树脂复合材料的微观形貌与动态热力学性能

通过模压成型，采用氧化石墨烯(GO)对四种碳纤维(CCF300、T700、CCF800、CCM40J)织物/环氧树脂(CF/EP)复合材料进行改性，通过复合材料的微观形貌、动态热力学性能等研究了GO对四种不同表面性质的CF/EP复合材料的改性效果。研究表明，添加GO后，GO/EP对四种CF的浸润性均比EP明显提高，纤维与GO/EP间的界面黏接比与EP基体间的黏接明显改善；CF/EP复合材料的破坏主要发生在CF与EP的界面，而GO的存在使GO-CF/EP复合材料的破坏由CF与EP基体的界面向GO/EP区域过渡。CF表面的氧碳比和沟槽均显著影响复合材料的玻璃化转变温度(T_g)，具有最高表面氧碳比的GO-CCF300/EP复合材料表现出最高的T_g，但沟槽更丰富的CCM40J和CCF300碳纤维对CF/EP复合材料的T_g表现出更好的GO改性效果。      

氧化石墨烯/天然橡胶-丁腈橡胶复合材料的制备与性能

为研究氧化石墨烯（GO）对共混橡胶的补强改性作用,首先,通过改进的Hummers方法制备了GO,并通过乳液共混法制备了GO/天然橡胶（NR）-丁腈橡胶（NBR）复合材料;然后,采用SEM、FTIR、XRD、溶胀测试和力学性能测试表征了GO、NR-NBR硫化胶和GO/NR-NBR复合材料的微观形态、结构和力学性能。结果表明:所得GO含有大量的含氧官能团,氧化效果较好;橡胶基体中GO分散均匀,且GO/NR-NBR复合材料的拉伸断面粗糙程度显著增加;GO的填充可以提高复合材料的表观交联密度;GO/NR-NBR复合材料的力学性能随着GO含量的增加而改善,当GO含量为3.0wt%时,GO/NR-NBR复合材料的拉伸强度、100%定伸应力和邵氏A硬度分别提高了53.3%、67.3%和10.5%,断裂伸长率降低了9.6%。      

MWCNTs对环氧树脂及多尺度MWCNTs-碳纤维/环氧树脂复合材料力学性能的影响

通过对胺基化多壁碳纳米管（MWCNTs-NH₂）进行改性,得到改性MWCNTs悬浮液（MWCNTs-NH₂（M））。分别将羧基化MWCNTs （MWCNTs-COOH）和MWCNTs-NH₂（M）分散在环氧树脂（EP）中,采用热熔法制备了多尺度MWCNTs-碳纤维（CF）/EP复合材料。研究了MWCNTs对EP模量、韧性及EP与CF之间界面黏结强度的影响,并分析了MWCNTs与CF上浆剂的作用,评价了多尺度MWCNTs-CF/EP复合材料的力学性能。结果表明：官能团化的MWCNTs可对EP的模量和韧性起到更好的增强作用。MWCNTs接枝的-COOH或-NH₂可与CF上浆剂中的环氧基团发生化学反应,提高EP与CF之间的界面剪切强度。MWCNTs-NH₂（M）对多尺度MWCNTs-CF/EP复合材料力学性能的增强效果优于MWCNTs-COOH,当MWCNTs-NH₂（M）的含量为1wt%时,多尺度复合材料的0°压缩强度、90°压缩强度、弯曲强度、弯曲模量、冲击后压缩强度（CAI）分别提高了16.7%、16.3%、40.9%、30.3%、20.6%。     

改性氧化石墨烯对环氧树脂基复合材料热膨胀系数影响的研究

环氧树脂(EP)热膨胀系数(CTE)为65×10~(-6)℃~(-1),碳纤维(CF)CTE为-12×10~(-6)℃~(-1),因此降低EP的CTE是提高碳纤维增强环氧树脂(CF/EP)复合材料低温使用性能的关键。采用氧化石墨烯(GO)和四氧化三铁改性氧化石墨烯(Fe_3O_4-GO)修饰EP,研究了GO及Fe_3O_4-GO对EP基体CTE的影响。结果表明:由于Fe_3O_4-GO表面的官能团可与EP基体形成共价键,从而加强了与EP基体的界面作用;相对于纯EP,GO和Fe_3O_4-GO改性EP的玻璃化转变温度(Tg)分别升高了3.71℃和5.74℃;相对于纯EP,GO和Fe_3O_4-GO改性EP在Tg下的CTE值分别降低了23.77%和33.61%,但在Tg上的CTE值均高于纯EP。     

氧化石墨烯的尺寸对碳纤维/环氧树脂湿热界面性能的影响

通过Hummers法获得两种尺寸的氧化石墨烯(GO),利用模压成型制备GO改性碳纤维增强环氧树脂复合材料(GO/CF/EP),并对复合材料进行湿热处理，利用层间剪切性能、动态热机械性能和微观形貌分析室温干态和湿热处理后复合材料的改性效果。结果表明：GO对复合材料的层间剪切强度和玻璃化转变温度均具有良好的改善作用；室温干态时两种尺寸GO对复合材料层间剪切强度的改善效果基本相同；随GO含量增加，小尺寸GO使复合材料的湿热层间剪切强度下降更快，GO含量为0.1%(质量分数，下同)时对复合材料的层间剪切性能改善作用较好，而GO含量为0.2%时对复合材料的玻璃化转变温度改善更好。随GO含量增加，GO-EP复合树脂基体的放热峰向低温移动，小尺寸GO使复合树脂的凝胶时间变短。微观形貌分析表明，GO的存在有利于增加复合材料破坏时的裂纹扩散路径，从而更有助于材料耗散裂纹尖端能量。     

氧化石墨烯纳米片层对水泥基复合材料的增韧效果及作用机制

通过氧化和超声波分散制备了氧化石墨烯（GO）纳米片层分散体系,研究了GO纳米片层对水泥基复合材料的增韧效果及作用机制。用EDS、FTIR、XRD、SEM和AFM对GO纳米片层的结构进行了表征。研究结果表明：所得GO含氧量为32.3wt%,GO纳米片层的厚度为6 nm左右,在GO片层表面含有羟基、羧基和磺酸基等活性基团。水泥基复合材料的SEM形貌及力学性能测定结果表明：当GO掺量为0.03wt%时,GO能够使水泥水化产物形成花朵状晶体,并使水泥基复合材料的拉伸强度、抗折强度和压缩强度比对照样品分别提高了65.5%、60.7%和38.9%。提出了GO纳米片层对水泥水化产物的模板调控机制,揭示了花状晶体的形成过程。     

氧化石墨烯-碳纳米管复合膜层间增韧碳纤维/环氧树脂复合材料

碳纤维增强树脂基复合材料层合板结构的层间性能一直是材料的性能短板,本文利用氧化石墨烯(GO)和碳纳米管(CNT)设计制备了具有一定渗透性和树脂浸润性的复合膜,采用层间增韧方法,制备了GO-CNT复合膜改性碳纤维/环氧树脂(CF/EP)复合材料,通过张开型Ⅰ型层间断裂韧性(G_ⅠC)与滑移型Ⅱ型层间断裂韧性(G_ⅡC)对GO-CNT-CF/EP复合材料的层间韧性进行了研究,并结合复合材料的破坏微观形貌和损伤/破坏特征分析了GO-CNT复合膜对复合材料的层间增韧效果及增韧机制。结果表明：GO与CNT质量比为3∶7时制备的复合膜具有良好的成膜工艺性和树脂浸润性,EP与GO-CNT复合膜的接触角远低于其与纯GO膜的接触角,并且GO与CNT结构中的羟基、羧基、环氧基等含氧基团增加了它们与EP的物理亲和性和化学作用,有利于复合材料层间GO-CNT/EP微区结构的强韧化。GO-CNT复合膜对复合材料的张开型层间断裂韧性G_ⅠC没有增强效果,甚至复合材料的G_ⅠC值还发生了轻微下降。而GO-CNT复合膜对复合材料的滑移型层...     

改性凹凸棒土-氧化石墨烯/环氧树脂复合材料的力学性能和热电性能

分别用硅烷偶联剂KH560改性凹凸棒土(Attapulgite，ATP)和氧化石墨烯(Graphene oxide，GO)，并将其复合制备ATP-GO复合物。以环氧树脂(Epoxy，EP)为基体，采用原位聚合法制备ATP-GO/EP复合材料。采用SEM和FTIR对ATP-GO复合物的形貌和化学结构进行表征。结果表明:ATP与GO成功键合并附着在GO表面；ATP-GO的加入，提高了EP的冲击强度、弯曲强度和热稳定性，降低了其介电常数和介电损耗。3wt%ATP-0.5wt%GO/EP复合材料的弯曲强度和冲击强度分别为138.58 MPa和20.80 kJ/m2，比纯EP分别提高了75.5%和351.6%，而其介电常数和介电损耗分别低至3.36和0.0118，比纯EP降低了7.7%和27.3%。      

Multifold interface and multilevel crack propagation mechanisms of graphene oxide/polyurethane/epoxy membranes interlaminar-toughened carbon fiber-reinforced polymer composites

Graphene oxide/polyurethane/epoxy (GO/PU/EP) membranes were directly fabricated by functionalization of graphene oxide with epoxy-grafted polyurethane (GO-UE), and the interface correlation and crack propagation mechanisms in GO/PU/EP membranes interlaminar-toughened carbon fiber-reinforced polymer composites were investigated. The functionalized GO-UE with corrugation and scrolling nature of graphene sheets was evenly dispersed in GO/PU/EP membranes below 0.50 wt% loading. Mode I fracture toughness, flexural properties and interlaminar shear strength of GO/PU/EP membranes-toughened composites were enhanced in comparison with untoughened composites and PU/EP membranes-toughened composites, which was ascribed to the multifold interface bonding between the GO-UE layers, epoxy matrix and carbon fiber. Schematic models of multilevel crack propagations were proposed based on different crack extension directions to GO-UE and the morphology evolutions of GO-UE in the interlaminar region and at the carbon fiber interface in toughened composites, which highlighted the toughening mechanisms of crack pinning, crack deflection and separation between GO-UE layers.     

氧化石墨烯有序排列对碳纤维增强环氧树脂复合材料低温性能影响

为了提高碳纤维增强环氧树脂复合材料在低温(77 K)循环条件下的微裂纹抗性,文中采用共沉淀法制备了具有良好顺磁性的四氧化三铁/氧化石墨烯(Fe_3O_4/GO),采用红外光谱、X射线衍射、扫描电镜、透射电镜等手段研究了Fe_3O_4/GO在环氧树脂基体中的有序排列对环氧树脂及碳纤维增强环氧树脂复合材料低温性能的影响。结果表明,Fe_3O_4/GO的有序排列可有效提高环氧树脂基体的低温力学性能及降低环氧树脂基体的热膨胀系数,并可明显改善碳纤维增强环氧树脂(CF/EP)复合材料的低温微裂纹抗性;相对于纯环氧树脂,改性环氧树脂的热膨胀系数和低温环境下的微裂纹密度分别降低了36.5%和37.5%。     

The effect of surface treatment on the interfacial properties in carbon fibre/epoxy matrix composites

Carbon fibres with different degrees of surface oxidation, as well as epoxy-sized fibres, were used to prepare epoxy composites in order to compare the effects of the fibres surface chemistry on the interfacial properties. X-ray photoelectron spectroscopy, water vapour adsorption measurements and contact angle examination were applied to characterize the carbon fibre surfaces. A correlation was found between the content of primary adsorption sites on the fibre surface and interlaminar shear strength (ILSS) of the composites. Higher values of ILSS obtained for the oxidized fibres containing composites are proposed to be due to the higher concentration of carboxylic groups created on the oxidized fibres surface and to the creation of chemical bonds at the fibre/epoxy matrix interface. Enthalpy of cure, reaction peak temperature and glass transition temperature of the composites were determined by differential scanning calorimetry.     

氧化石墨烯/聚氨酯杂化膜的原位聚合构建及气体渗透性

采用Hummers法制备了3种不同氧化程度的氧化石墨烯(GO),通过聚氨酯(PU)单体(4,4’-二异氰酸苯酯(MDI)和1,4-丁二醇(BDO))与GO的原位聚合构建了GO/PU杂化膜。利用XRD、Raman、FTIR和TEM等表征了GO的结构;探讨了GO填充量对GO/PU杂化膜的形貌和CO2、N2渗透性的影响。结果表明:3种不同氧化程度的GO均呈完全剥离状态,为半透明片状结构;随着氧化程度的增加,拉曼D峰与G峰的相对强度比分别为0.947、1.103和1.245;GO的氧化程度对GO在溶剂和杂化膜中的分散性有较大影响,氧化程度越高,分散性越好。GO/PU杂化膜的CO2、N2渗透系数及CO2/N2渗透选择因子均随GO填充量的增加先增大后减小;当中等氧化程度的GO(M-GO)与(MDI+BDO)的质量比为1.0%时,M-GO/PU杂化膜的CO2渗透系数为63.6×10-13 cm3(STP)/(cm·Pa·s),其中STP表示标准温度及压力,CO2/N2渗透选择因子可达48.5;填充适量的GO能显著提高GO/PU杂化膜的CO2渗透性及CO2/N2渗透选择性。     

Improved fracture toughness and fatigue life of carbon fiber reinforced epoxy composite due to incorporation of rubber nanoparticles

In this study, core–shell rubber (CSR) nanoparticles with approximate particle size of 35 nm were used as a modifier for the epoxy polymer. The effects of various CSR contents in the epoxy matrix on mode I interlaminar fracture toughness, tensile strength, and fatigue life of the carbon fabric reinforced epoxy (CF/EP) composites were investigated. The experimental results showed that the mode I interlaminar fracture toughness at crack initiation and propagation significantly improved by 71.21 and 58.47 %, respectively, when 8.0 wt% CSR was dispersed in the epoxy matrix. The fatigue life of the modified CF/EP composites at all of CSR contents dramatically increased 75–100 times longer than that of the unmodified CF/EP composites at high cycle fatigue while tensile strength slightly increased by about 10 %. Field emission scanning electron microcopy (FESEM) observations of the fracture surfaces were conducted to explain failure mechanisms of CSR addition to the CF/EP composites. The evidences of the rubber nanoparticle debonding, plastic void growth, and microshear banding were credited for delaying the onset of matrix crack, and reducing the crack growth rate, as a result, attributed to increase in the mechanical properties of the CF/EP composites.     

CNTs强化碳纤维/环氧复合材料界面过渡层及其对界面性能的影响

采用上浆的方法将碳纳米管(CNTs)引入到碳纤维表面,制备CF/CNTs/环氧多尺度复合材料。相比上浆处理前,复合材料的层间剪切强度及弯曲强度分别提高了13.54%和12.88%。采用力调制原子力显微镜及扫描电镜的线扫描功能对复合材料界面相精细结构进行分析。结果表明:CNTs的引入在纤维和基体间构建了一种CNTs增强环氧树脂的界面过渡层。该界面过渡层具有一定厚度,且其模量和碳元素含量呈梯度分布。在固化成型前对含有CNTs的复合材料进行超声处理,促使碳纤维表面的CNTs向周围树脂中分散,发现复合材料的界面过渡层被弱化,其层间剪切强度及弯曲强度较超声处理前分别下降了7.33%和5.34%,验证了CNTs强化的界面过渡层对于提高复合材料界面性能的重要作用。     

Covalent grafting of triazine derivatives onto graphene oxide for preparation of epoxy composites with improved interfacial and mechanical properties

Interface interactions are the important problems in improving the mechanical properties of graphene and polymer composites. In this work, a simple method is proposed to prepare epoxy composites with admirable properties through constructing dendrimers with cyanuric chloride (TCT) and diethylenetriamine (DETA) onto graphene oxide (GO) surface. The FTIR, XRD, XPS, Raman spectroscopy, SEM and TEM were used to confirm the successful grafting of TCT and DETA molecules onto the surface of GO. The interfacial adhesion between GO–TCT–DETA and epoxy resin is enhanced due to the formation of a strong chemical bond between the amino group on the GO surface and the epoxy resins. The tensile and flexural strength of GO–TCT–DETA/epoxy composites have considerable improvement (40.79 and 48.56%) compared with that of epoxy resin due to stronger interfacial interaction. In addition, the strengthening mechanism and dispersion of GO–TCT–DETA in epoxy matrix were also demonstrated.