碳纳米管加入方式对碳纤维/环氧树脂复合材料层间性能的影响

针对碳纤维/环氧树脂预浸料,对比了直接在树脂中加入碳纳米管(CNTs)后制备预浸料以及将CNTs喷涂在预浸料表面2种CNTs加入方式对CNTs-碳纤维/环氧树脂复合材料层合板I型与II型层间断裂韧性及层间剪切强度的影响。通过对树脂黏度、固化反应以及玻璃化转变温度的考察,分析了CNTs含量对树脂性能的影响,考察了添加方法对CNTs长度与形态的影响。分析了2种CNTs加入方式对CNTs-碳纤维/环氧树脂层合板断裂韧性及层间剪切强度的改善效果与作用规律。结果表明:CNTs的加入使树脂的黏度提高,固化反应程度下降;2种分散方法对CNTs的长度与形态无明显影响;直接在树脂中加入CNTs对CNTs-碳纤维/环氧树脂复合材料I型与II型层间断裂韧性的提高效果低于在碳纤维/环氧树脂预浸料表面喷涂CNTs的方式,后者的CNTs利用率较高;由于CNTs团聚及对树脂固化反应的影响,CNTs含量过高会使得其对CNTs-碳纤维/环氧树脂层合板的增韧效果下降。     

碳纳米管接枝炭纤维对环氧树脂浸润性能的影响

以乙炔为碳源、二茂铁为催化剂,通过雾化辅助化学气相沉积法(AACVD)制备多尺度杂化材料CNT/CF.利用扫描电镜(SEM)、透射电镜(TEM)表征所制CNr/CF的形貌及其微观结构.结果表明:在反应温度750℃～800℃、沉积30min的条件下,碳纳米管(CNTs)能够以较高的密度均匀生长在炭纤维表面形成多尺度杂化材料CNr/CF.单纤维拉伸测试表明:在700℃～800℃、沉积30min的条件下所制CNT/CF的单纤维拉伸强度降低幅度小于13％;在反应温度750℃、沉积40 min的条件下、单纤维拉伸强度降低幅度小于10％.纤维悬挂液滴法研究表明:所制CNT/CF比原始炭纤维对环氧树脂有更好的浸润性能.     

电泳沉积CNTs掺杂C/C复合材料的微观组织与弯曲性能

采用电泳沉积(EPD)在1k碳布表面均匀加载了碳纳米管(CNTs), 借助化学气相沉积(CVD)致密化碳布叠层预制体, 制备了EPD CNTs掺杂的二维(2D)碳/碳(C/C)复合材料。研究了EPD CNTs对2D C/C复合材料致密化过程、微观组织和弯曲性能的影响。研究结果表明: EPD CNTs在碳纤维表面呈现平面内高密度、杂乱取向分布特征, 该形貌CNTs降低了热解炭在碳纤维预制体内的沉积速率, 诱导了高石墨微晶堆垛高度(L_c)、低(002)晶面面内方向上的沉积有序度(L_a)热解炭的形成; EPD CNTs的掺杂可提高C/C复合材料的弯曲强度和模量: 当CNTs含量为0.74wt%时, 复合材料弯曲强度和模量可达150.83 MPa和23.44 GPa, 比纯C/C复合材料提高了31.4%和13.9%; 继续提高CNTs含量, 复合材料弯曲强度降低, 这与过高含量EPD CNTs导致复合材料密度降低有关; 同时, EPD CNTs的掺杂使得C/C复合材料断裂模式由脆性断裂转变为假塑性断裂, 复合材料断裂塑性的提高是由于EPD CNTs造成的碳基体结构的变化以及碳纤维的大量拔出。     

CF-CNTs多尺度增强体的制备及CF-CNTs/环氧树脂复合材料力学性能

利用化学气相沉积(CVD)法在碳纤维(CF)表面生长碳纳米管(CNTs),制备了CF-CNTs多尺度增强体,增强体与环氧树脂(EP)结合得到CF-CNTs/EP复合材料。采用场发射扫描电镜(FESEM)、高分辨透射电镜(HRTEM)等方法研究了不同CVD工艺参数对CF-CNTs多尺度增强体的影响,并研究了不同CVD时间对CFCNTs/EP复合材料力学性能的影响。结果表明:沉积温度为500℃、沉积时间为10min、反应压力为0.02 MPa时,制备得到的多尺度增强体性能最好。CF-CNTs多尺度增强体较未生长CNTs的碳纤维与环氧树脂的浸润性明显提高。在CVD时间为10min时,所得CF-CNTs/EP复合材料的界面剪切强度(IFSS)最大可提高90.6%,层间剪切强度(ILSS)最大可提高24.4%。同时,在制备环氧树脂复合材料过程中碳纤维的不加捻与加捻相比,其ILSS提高了11.3%。     

玄武岩纤维表面生长碳纳米管及其复合材料性能的研究

针对玄武岩纤维(CBF)表面光滑且惰性,在与树脂基体复合制备复合材料时二者结合能力较低的问题,采用化学镀镍在玄武岩纤维表面均匀加载镍催化剂,借助化学气相沉积(CVD)生长碳纳米管(CNTs)。用场发射扫描电镜(FESEM)、透射电镜(TEM)、拉曼光谱(Raman)等方法对生长的CNTs进行表征,并测试复合材料的界面剪切强度。结果表明化学镀镍工艺能在CBF表面均匀加载镍催化剂,有利于CVD生长CNTs。工艺最佳条件为施镀时间15min、500℃下生长10min,此条件下生长的CNTs整齐排列在CBF表面,结晶性较好且呈中空管状。采用生长了CNTs的CBF制备复合材料的界面强度提高了10%。     

分散方法对低含量碳纳米管玻纤/环氧层板性能的影响

采用超声波振荡与超声波破碎两种分散方法制备了低含量碳纳米管(CNTs)增强的环氧树脂, 研究了CNTs对树脂流变特性、 固化特性和力学性能的影响。进一步采用该树脂体系通过真空灌注工艺(VARIM)制备了CNTs含量为0.01%的CNTs-玻璃纤维/环氧树脂复合材料层板, 研究了两种分散方式下CNTs对复合材料层板力学性能的影响和CNTs的增强机制。结果表明: 超声波破碎分散使CNTs长度变短, 分散性更好, 与超声波振荡分散方式相比, CNTs对树脂增黏效果和树脂固化反应的影响更明显。采用双真空灌注工艺, 两种超声波分散方式下CNTs均提高了复合材料的弯曲性能、 层间剪切性能和树脂与纤维的粘结强度, 而单真空灌注工艺下CNTs的增强效果不明显, 说明受纤维过滤作用的影响, 选择合适的灌注工艺和CNTs分散方式, 低含量CNTs可实现对灌注工艺复合材料层板的增强。     

镍铁氧体/聚苯乙烯复合材料的制备与性能

采用高分子凝胶法制备了纳米镍铁氧体,然后用热压法制备了镍铁氧体/聚苯乙烯复合材料.镍铁氧体的结构、形貌和复合材料的电磁性能分别采用X射线衍射仪(XRD)、透射电镜(TEM)和HP8510网络分析仪进行了研究.结果表明,当煅烧温度为600℃时,镍铁氧体晶相生成.随着煅烧温度的升高,镍铁氧体晶体晶型趋向完整.在X波段,复合材料的复介电常数和复磁导率值随着镍铁氧体煅烧温度的升高而增大.1000℃煅烧的镍铁氧体所制备的镍铁氧体/苯乙烯复合材料在11.47GHz处的最小反射率为-12.67dB.     

超音速激光沉积增材制造CNTs/Cu复合材料微观结构及力学性能研究

目的 研究超音速激光沉积增材制造CNTs/Cu复合材料的微观结构及力学性能。方法 对CNTs进行表面镀铜处理,提高它与Cu黏接相之间的润湿性,增强CNTs/Cu之间的界面结合,利用超音速激光沉积技术(Supersonic Laser Deposition,SLD)增材制备不同CNTs含量的CNTs/Cu复合材料,对比研究了CNTs含量和退火温度对CNTs/Cu复合材料微观结构及力学性能的影响规律,并采用能谱仪对拉伸断口微区进行元素分析测定。结果 SLD制备的CNTs/Cu复合材料具有优异的塑性变形能力,而强度较高的CNTs通过嵌入铜粉颗粒之间的缝隙提升了沉积质量。对复合材料微观组织进行表征发现组织无明显孔隙、致密性良好,且无烧蚀现象。CNTs的加入有效提高了CNTs/Cu复合材料的抗拉性能,并且随着CNTs含量的上升,CNTs/Cu复合材料的极限抗拉强度(Ultimate Tensile Strength,UTS)稳步上升;当CNTs质量分数为0.3%时,CNTs/Cu复合材料的UTS为36.33 MPa,是CNTs质量分数为0.05%时的1.35倍。随着退火温度的升高,CNTs/Cu复合材料的UTS表现为先增大后减小的趋势,在500 ℃时UTS达到最大值。结论 由于激光加热软化的效果与表面镀铜的包覆作用,CNTs能够均匀地分布在CNTs/Cu复合材料内部,同时明显增强复合材料内部颗粒的界面结合强度,后续的热处理有助于使材料从不稳定的机械结合逐步转换为冶金结合,显著提高复合材料的抗拉性能。     

碳纳米管/聚苯胺化学修饰电极的制备及其对抗坏血酸的检测

通过恒电压沉积法将纳米金属镍沉积于石墨电极表面, 经化学气相沉积法在石墨电极表面原位生长出碳纳米管(CNTs), 通过电化学聚合法在CNTs表面原位聚合聚苯胺, 从而获得化学修饰电极。采用扫描电子显微镜对所得电极形貌结构进行表征, 并研究CNTs与PNAI复合电极对抗坏血酸(AA)的检测效果。研究结果表明: 制备的CNTs都能均匀地生长在石墨电极表面, 纳米中空管状结构都保持完好; PANI均匀地包覆在CNTs管壁上, 复合材料呈现出典型的三维网状结构。所制备的CNTs/PANI修饰电极对AA具有良好的电化学响应, 其中管径较小CNTs的修饰电极对AA的电化学响应更强: 具有更宽的检测范围和更低的检出限。其检测线性范围为1.0×10^-6~4.5×10^-4 mol/L, 检出限为1.0×10^-7 mol/L (S/N = 3)。且具有良好的稳定性、重复性和可靠性。     

表面活性剂对CNTs/EP复合材料性能的影响

以十二烷基苯磺酸钠(SDBS)为表面活性剂,采用超声分散工艺对碳纳米管(CNTs)进行包覆处理,将不同含量的CNTs与处理后的CNTs分别与环氧树脂(EP)球磨混合后制备CNTs/EP复合材料。采用透射电镜表征CNTs的微观形貌,并观察冲击试样断口形貌。结果表明:处理后的CNTs/EP较原CNTs具有良好的分散性,与树脂界面结合紧密,断口为韧性断裂。当处理后的CNTs含量为3%(wt,质量分数),制得的CNTs/EP复合材料的抗拉强度和冲击强度分别为72.5MPa和32.5kJ/m2,比未经处理的CNTs制得的CNTs/EP复合材料分别增长16.00%和41.30%,SDBS包覆处理效果明显。     

Processing,characterization, and modeling of carbon nanotube-reinforced multiscale composites

Carbon fiber-reinforced epoxy composites modified with carbon nanotubes (CNTs) were fabricated and characterized. High-energy sonication was used to disperse CNTs in the resin, followed by infiltration of fiber preform with the resin/CNT mixture. The effects of sonication time on the mechanical properties of “multiscale” composites, which contain reinforcements at varying scales, were studied. A low CNT loading of 0.3 wt% in resin had little influence on tensile properties, while it improved the flexural modulus, strength, and percent strain to break by 11.6%, 18.0%, and 11.4%, respectively, as compared to the control carbon fiber/epoxy composite. While sonication is an effective method to disperse CNTs in a resin, duration, intensity, and temperature need to be controlled to prevent damages imposed on CNTs and premature resin curing. A combination of Halpin–Tsai equations and woven fiber micromechanics was used in hierarchy to predict the mechanical properties of multiscale composites, and the discrepancies between the predicted and experimental values are explained.     

氧化镍掺杂酚醛树脂热解炭的结构及抗氧化性

在普通酚醛树脂中直接掺杂氧化镍粉末,研究氧化镍掺量和炭化处理温度对树脂热解炭的结构与氧化过程的影响,用X射线衍射仪、拉曼光谱分析仪、扫描电镜和综合差热分析仪等对掺杂改性树脂热解炭的石墨化度、显微结构及氧化过程分析表征,结果表明,在埋炭条件下掺杂改性树脂在450-750℃的炭化处理中三氧化二镍被逐级还原为一氧化镍和单质镍后,碳原子在镍颗粒上沉积生长,形成晶须、片状或块状结构的热解炭,热解炭石墨化程度取决于炭化温度和氧化镍掺杂量,在高于1050℃炭化处理的热解炭中出现明显的石墨化炭峰,随着掺杂量增加,热解炭石墨化程度大大增加,氧化温度比普通树脂明显提高,且以3~5%的掺杂量为佳。     

Vibration damping characteristics of carbon fiber-reinforced composites containing multi-walled carbon nanotubes

Vibration damping characteristic of nanocomposites and carbon fiber reinforced polymer composites (CFRPs) containing multiwall carbon nanotubes (CNTs) have been studied using the free and forced vibration tests. Several vibration parameters are varied to characterize the damping behavior in different amplitudes, natural frequencies and vibration modes. The damping ratio of the hybrid composites is enhanced with the addition of CNTs, which is attributed to sliding at the CNT-matrix interfaces. The damping ratio is dependent on the amplitude as a result of the random orientation of CNTs in the epoxy matrix. The natural frequency shows negligible influence on the damping properties. The forced vibration test indicates that the damping ratios of the CFRP composites increase with increasing CNT content in both the 1st and 2nd vibration modes. The CNT-epoxy nanocomposites also show similar increasing trends of damping ratio with CNT content, indicating the enhanced damping property of CFRPs arising mainly from the improved damping property of the modified matrix. The dynamic mechanical analysis further confirms that the CNTs have a strong influence on the composites damping properties. Both the dynamic loss modulus and loss factor of the nanocomposites and the corresponding CFRPs show consistent increases with the addition of CNTs, an indication of enhanced damping performance.     

Comparison of drying methods for the preparation of carbon fiber felt/carbon nanotubes modified epoxy composites

Carbon fiber felt with carbon nanotubes (CNTs) were prepared by immersing three-dimensional (3D) felt into CNT aqueous solution (with dispersant) followed by removing water with different drying methods. Epoxy resin was then introduced into the felt to obtain 3D fiber felt/CNTs modified epoxy composites. This paper highlights the effect of drying method on macro-morphologies of the felt, morphological dispersion of CNTs and some relevant properties of the composites, including electrical conductivity and flexural performance. The results demonstrate that compared to the commonly used heat drying method, freeze drying technique possesses obvious advantages for the fabrication of fiber felt/CNT modified epoxy composites.     

T700碳纤维增强环氧树脂基复合材料自然老化性能与机制

为验证复合材料的耐久性,对T700碳纤维增强环氧树脂基复合材料经自然老化后的微观形貌、表面元素含量、热性能与力学性能等进行了研究。结果表明: 在光氧老化与热氧老化的共同作用下,T700碳纤维增强EP-A环氧树脂基（T700/EP-A）复合材料表层树脂将发生老化降解,并且随自然老化时间的延长,T700/EP-A复合材料的玻璃化转变温度逐渐降低,未老化试样的玻璃化转变温度为207℃,经过自然老化处理3年后,其玻璃化转变温度降低为180℃,延长自然老化时间至5年时,其玻璃化转变温度进一步降低至172℃。而自然老化过程对复合材料力学性能可能同时存在着增强效应与损伤效应,因此造成了T700/EP-A与T700/EP-B复合材料的不同力学性能表现出相异的变化趋势。随自然老化时间延长,T700/EP-A与T700/EP-B复合材料纵向拉伸强度表现出先升高后降低的趋势,纵向弯曲强度表现出逐渐升高的趋势,纵向压缩强度与层间剪切强度存在波动,未呈现出明显变化。      

Effects of amino group on the properties of carbon nanotubes

The surfaces of multi-walled carbon nanotubes were grafted with amino functional groups by reacting acyl-chloride-functionalized carbon nanotubes (CNTs) with hexamethylene diamine, which improves the surfactivity of CNTs. The dispersity, surface morphology, and thermogravimetry of acid-treated and amino-functionalized CNTs were investigated. Amino-functionalized CNTs were added into epoxy resin to analyze the effects of amino functional groups on the properties of resin composites. It was found that the properties of CNTs, such as morphology and scale, were not affected by amino functional groups, but the dispersity in water was highly improved. Amino-functionalized CNTs are better dispersed in resin matrix, and the mechanical properties of composites are improved significantly, whereas the conductivity of composites is not enhanced as expected.     

退火温度对Pb(Zr_(0.53)Ti_(0.47))O_3薄膜结构及其性能的影响

采用sol-gel法在Pt/Ti/SiO_2/Si衬底上制备Pb(Zr_(0.53)Ti_(0.47))O_3薄膜.利用X射线衍射仪(XRD)和原子力显微镜(AFM)对其晶格结构和微观形貌进行了表征,通过改变退火温度制得了具有单一钙钛矿结构的Pb(Zr_(0.53)Ti_(0.47))O_3薄膜.然后将该薄膜与环氧树脂形成复合结构材料.对其铁电性能以及复合材料的阻尼性能进行了测试,结果表明,退火温度的升高有利于改善薄膜的铁电性能,在750℃下退火的Pb(Zr_(0.53)Ti_(0.47))O_3薄膜,其剩余极化值2Pr达到了68.6μC/cm~2, 矫顽场强2E_c达到158.7kV/cm;同时退火温度的升高还有利于薄膜致密度的提高,对复合材料的阻尼性能也有一定的改善,当退火温度达到800℃,复合材料的阻尼损耗因子达到最大值,阻尼温域最宽,阻尼性能最好.     

不同热氧环境对T800碳纤维/环氧树脂复合材料力学性能的影响EI北大核心CSCD

不同热氧环境(70,130,190℃)对碳纤维复合材料的性能有着重要的影响。分析了不同热氧环境下T800碳纤维/环氧树脂复合材料的失重特性,并对比了老化前后的表面形貌、红外光谱、动态力学性能和层间剪切性能。结果表明:在热氧老化初始阶段,质损率急速上升,老化温度越高质量损失越快;试样表面形貌随热氧温度的升高其破坏程度逐渐加剧,在190℃老化后,纤维表面树脂脱落严重,纤维与纤维之间出现裂缝空隙,无树脂填充,在此老化温度下,试样发生了不可逆化学变化;试样的玻璃化转变温度会随老化温度的升高而变大,但内耗呈现先降低后增大再降低的趋势,在70,130,190℃热氧老化后试样剪切强度分别提高6.0%,13.7%和2.1%。相关实验结果和实验现象可为后续研究新型国产T800碳纤维/环氧复合材料提供数据参考。     

Dynamic Mechanical Analysis of Hybrid Fibre/Glass Microspheres Composites

Abstract: This article presents the results obtained in a current study of the viscous properties on hybrid short fibre/hollow glass microspheres composites fabricated with epoxy binder. The effect of the filler volume fraction and of the fibre reinforcement on the dynamic stiffness modulus, damping coefficient and glass transition temperature was studied. These properties were determined using dynamic mechanical analysis (DMA) in three points bending mode. The specimens were cut from plates produced by vacuum resin transfer moulding with microspheres weight contents up to 17%. Net resin exhibits storage modulus significantly higher than the 2% in weight of microspheres foam, while negligible effect was observed on the maximum loss modulus, maximum damping coefficient and glass transition temperature. The increase in filler volume fraction tends to decrease significantly storage and loss modulus at stable regions and the maximum damping coefficient, while glass transition temperature is only marginally affected. The addition of low contents of short fibre increases significantly storage modulus, particularly for carbon fibre, while maximum loss modulus does not exhibit a well‐defined tendency. Important reduction in the maximum damping coefficient was observed by the addition of both fibre reinforcements.