电场诱导碳纳米管在聚合物中定向有序排列的研究进展

碳纳米管特殊的结构和优异的性能使之成为复合材料增强的首选填料,综述了电场条件下碳纳米管在聚合物中有序排列的研究进展。分析了电场类型、碳纳米管表面官能化、加电时间、碳纳米管尺寸和含量等因素对电场诱导碳纳米管有序排列的影响,讨论了定向有序排列的碳纳米管对复合材料的力学、电学和热学等性能的影响,分析了碳纳米管定向排列机理以及碳纳米管定向程度的表征方法。     

增强材料的排列形式对复合材料隔声性能影响的实验研究

为了探讨复合结构与隔声性能之间的关系 , 探索降低低频噪声的新途径 , 设计并制备了增强材料纵向排列和横向排列的玻璃纤维织物/聚氯乙烯复合材料 , 采用混响室2静音箱法对其隔声性能进行了测试分析。研究表明: 增强材料的排列形式对复合材料的隔声性能有明显的影响 , 复合材料的厚度超过 5 mm后 , 在相同厚度和面密度的条件下 , 纵向排列的玻璃纤维织物增强复合材料比横向排列的玻璃纤维织物增强复合材料对低频和低2中频的隔声性能好 ; 且随着复合材料厚度的增加其差异增大。因此 , 可以通过改变增强材料的排列形式来改善复合材料对低频和低2中频噪声的隔声性能。      

反复拉伸法制备单壁碳纳米管定向排列的SWCNT／PMMA复合材料

采用反复机械拉伸法制备了单壁碳纳米管(SWCNTs)均匀分散且定向排列的SWCNT/聚甲基丙烯酸甲酯(PMMA)复合材料.将半干状态的SWCNT/PMMA复合体沿同一方向反复拉伸100次,每次的拉伸比为50,每次拉伸完以后,将聚合物沿拉伸的方向反复重叠.SEM,偏振拉曼光谱分析均表明SWCNTs沿拉伸方向排列.电学与力学测试结果表明:与PMMA相比,复合材料的电导率、弹性模最、拉伸强度和延伸率均得到明显提高,并表现出显著各向异性,复合材料滑拉伸方向的电学和力学性能显著高于其垂直于碳纳米管排列方向的值.     

金属基复合材料微屈服行为的力学分析与试验

本文采用细观力学计算、有限元分析和试验测试等方法,定量研究了短纤维增强金属基复合材料微屈服过程中应力应变分布和微屈服规律,结果表明不同短纤维分布朝向、体积比的Al2O3-SiO2(sf)/Al-Si复合材料微屈服行为符合Brown-Lukens关系,在增强体短纤维附近存在较大应力集中,晶粒直径、位错密度等材料参数对等效应力影响不大,对等效塑性应变有显著影响,同时分析了增强体短纤维的体积含量和短纤维分布状态对材料微屈服强度的影响。     

碳纳米管/聚合物复合材料抗压性能的多尺度模拟

众所周知,碳纳米管不但具有极高的硬度和强度,而且具备高长径比及低密度特征,使其成为了良好的纳米复合材料增强剂,广泛用于增强材料的硬度和强度.已有研究证明纳米管在基质中良好的分散与排列,对材料的改性有很大影响.     

TiO_2纳米管/碳纳米管复合材料光催化降解玫瑰红染料废水的研究

主要介绍水热法制备TiO2纳米管/碳纳米管(TiO2/CNT)复合材料及其光催化降解染料废水的研究。结果表明,用水热法制备出的TiO2纳米管和CNT的掺杂比例为5∶1时,TiO2纳米管/碳纳米管(TiO2/CNT)复合材料光催化降解玫瑰红染料废水的效果最佳,而且TiO2纳米管/碳纳米管复合材料具有较好的稳定性。研究证实了TiO2纳米管/碳纳米管复合材料对玫瑰红染料废水在模拟太阳光照射下具有较好的光催化效果。     

湿热环境对碳纳米管复合材料界面应力传递的影响

基于碳纳米管的热膨胀系数及弹性模量分别为温度变化的函数,基体的热、湿膨胀系数及弹性模量分别为温度变化和湿度变化的函数,应用连续介质力学的经典弹性壳理论及传统纤维拉拔模型,分析了湿热环境对碳纳米管复合材料界面应力传递的影响。数值计算表明,湿度、温度的效应及碳纳米管的层数等参数对界面应力的传递均有显著影响。     

2D-C/SiC复合材料的主泊松比演化行为

泊松比是材料及其结构力学性能分析的重要参数之一。本文旨在研究2D-C/SiC复合材料主泊松比的非线性演化行为。首先，基于Mini复合材料模型与正交层压板模型，考虑纤维的横观各向同性性质，建立了2D-C/SiC复合材料的热残余应力计算模型；其次，应用剪滞理论与经典层压板理论，考虑材料的损伤与热残余应力释放机制，建立了2D-C/SiC复合材料的主泊松比计算模型；最后，通过试验表征了材料的应变响应及泊松比演化规律，并对理论模型进行了分析验证。结果表明，2D-C/SiC复合材料内部热残余应力较大，拉伸损伤过程中的热残余应力释放是负泊松比产生的原因；应力-应变曲线及泊松比演化曲线的模型预测结果均与试验曲线吻合较好，表明了理论分析模型的准确性与合理性。     

缺陷碳纳米材料及其改性补强橡胶复合材料研究进展

碳纳米管、石墨烯具有优异的机械性能和热力学性能，已成为新一代增强橡胶复合材料性能的重要补强材料。然而，在实际生产中，容易产生缺陷碳纳米管和石墨烯且两者在橡胶复合材料基体内也极易发生团聚。为解决上述问题最常用的方法是对缺陷碳纳米管和石墨烯进行官能化处理。总结了碳纳米管、石墨烯以及缺陷、官能化碳纳米管和石墨烯对橡胶复合材料力学、摩擦学、老化等性能的影响，并对该领域未来的发展提出建议。     

复合材料弹性模量随机计算模型

从纤维在复合材料中排列不规则的事实出发, 运用数值模拟的方法初步研究了纤维排列的随机性, 并将结果初步应用在复合材料模量的细观力学计算当中, 发现纤维随机排列对细观力学研究复合材料的力学性能有较大的影响, 表明如何在复合材料细观力学中恰当地考虑纤维随机排列是一个值得研究的问题。      

碳纳米管复合材料的应力分析

采用三相同轴柱壳剪切滞后模型,分析含有界面层的碳纳米管复合材料中的应力场、饱和应力和应力传递效率以及碳纳米管的有效长度。碳纳米管复合材料的界面层厚度与碳纳米管直径尺度（0.1~100nm）相当,在进行应力分析时应该考虑界面层的影响。分析表明:界面层的存在以及其厚度的增大都明显地降低应力传递效率和纤维的饱和应力,但增大了碳纳米管纤维的有效长度。此外碳纳米管的长径比较小时,对应力传递效率和碳纳米管有效长度均有较明显的影响。      

Properties of composites of carbon nanotube fibres

Composites have set the standard for high strength materials for several decades. With the discovery of nanotubes, new possibilities for reinforced composites have arisen, with potential mechanical properties superior to those of currently available materials. This paper reports the properties of epoxy matrix reinforced with fibres of carbon nanotubes (CNTs) which, in many ways, are similar to standard composites reinforced with commercial fibres. The composites were formed by the back diffusion of the uncured epoxy into an array of aligned fibres of CNTs. The fibre density and volume fraction were measured from thermogravimetric analysis (TGA). Properties in tension and compression were measured, and the level of fibre–matrix interaction analysed fractographically. The results show the significant potential for this route to CNT reinforcement.     

Shear lag analysis of a novel short fuzzy fiber-reinforced composite

A novel short fuzzy fiber-reinforced composite (SFFRC) in which the aligned short carbon fiber reinforcements are coated with radially aligned carbon nanotubes (CNTs) is considered in this study. A three-phase shear lag model considering radial and axial deformations of the different constituent phases of the SFFRC has been developed to analyze the stress transfer mechanisms of the SFFRC. Traditionally, the shear lag models have been developed with an application of the axial load only on the representative volume element (RVE) of the composite in an attempt for analyzing the stress transfer between the fiber and the matrix. The three-phase shear lag model derived in this study analyzes the stress transfer to the short carbon fiber considering the application of the axial as well as the radial loads on the RVE of the SFFRC. It is found that if the carbon fiber is coated with radially aligned CNTs, then the axial load transferred to the fiber is significantly reduced due to the radial stiffening of the polymer matrix by CNTs. When compared with the results without CNTs, it is found that almost ~20 and ~29 % reductions in the maximum axial stress in the carbon fiber and the interfacial shear stress along its length occur, respectively, if the value of the applied radial load is twice of the applied axial load and the value of the CNT volume fraction is 0.0236 in the SFFRC. Effects of the variation of the carbon fiber aspect ratio, the carbon fiber volume fraction, and the application of the radial load on the load transfer characteristics of the SFFRC are also investigated.     

Effects of the carbon nanotube distribution on the macroscopic stiffness of composite materials

Having extremely high stiffness and low specific weight, carbon nanotubes (CNTs) have been known recently as perfect reinforcing fibers in nanotechnology. They can improve the stiffness and strength of nanocomposites by being used as reinforcing elements for example in polymer matrices. The corresponding properties of the fibers and matrix, such as volume fraction and aspect ratio are some of the significant factors in the characterization of mechanical properties of CNT reinforced composites. In recent years, the way in which fibers are distributed inside the matrix, in terms of randomness, has introduced another important factor in characterizing the mechanical properties of such composites. Based on this factor, composites can be classified into two types namely, aligned and randomly distributed. This research has studied the effect of random distribution of fibers in the matrix on the elastic modulus and initial yield stress of the nanocomposite. Therefore, several models of composites, with different distribution of fibers, were considered while holding the volume fractions and aspect ratio constant. As a result, the effect of randomness on the effective modulus of CNT reinforced composites was estimated. The finite element method (FEM), using the MSC.Marc software, was employed to predict the effective modulus of CNT reinforced composites and the results were successfully validated by comparison with the analytical Halpin-Tsai method.     

Dispersion evaluation,processing and tensile properties of carbon nanotubes-modified epoxy composites prepared by high pressure homogenization

In this paper, high pressure homogenization (HPH) served as the main dispersion method for making carbon nanotubes (CNTs)-modified composite materials. A new quantitative approach was proposed to evaluate the dispersion of CNTs in epoxy resin by combining microscopic images with maximum likelihood estimation theory. The results were in good agreement with those obtained from optical observation and ultraviolet–visible (UV–vis) absorbance measurement. Moreover, the dispersion process specific to HPH processing was analyzed with the aid of the proposed approach. The changes of the morphologies and lengths of CNTs in HPH were illustrated. It was found that, in the first few cycles, the lengths of CNTs fell significantly and the entanglements remained severe. In the following cycles, individual CNTs were gradually separated from agglomerates and the lengths experienced a slow decline. After homogeneous dispersion, the transverse tensile properties of CNTs-modified carbon fiber reinforced epoxy composites (CFRP) got obviously ameliorated.     

碳纳米管/羟基磷灰石复合材料的制备及表征

以含钴介孔分子筛为催化剂、乙醇为碳源, 采用CVD法制备碳纳米管(CNTs)。通过原位合成法制备一系列不同碳纳米管含量的碳纳米管/羟基磷灰石(CNTs/HA)复合材料。分别采用XRD、FTIR、TEM、N₂吸附-脱附和Raman光谱等分析手段, 对所合成CNTs/HA复合材料的晶相、结构、形貌和比表面积等进行了表征。同时研究了碳纳米管的添加量对所合成CNTs/HA复合材料形貌的影响。XRD与Raman结果表明, 所得CNTs/HA复合粉体中仅有CNTs与HA两种物相, 纯度较高, 结晶度较好; TEM结果显示, CNTs/HA复合材料中CNTs表面均匀包裹着一层纳米级的针状HA晶粒, 两者形成了较强的界面结合, 且当CNTs与HA的质量比为3:17时, CNTs与HA形成最佳结合状态; N₂吸附-脱附表征结果表明, 与HA的比表面积相比, CNTs/HA复合材料具有较高比表面积。     

碳纳米管/PLA复合材料制备及性能

采用溶液共混法制备纯化和酸化碳纳米管(CNTs)/PLA(聚乳酸)复合膜, 并对CNTs的分散性以及材料的结晶形态、 电性能和降解性能进行了研究。结果表明, 通过SEM观察到经过酸化处理的CNTs能较好地分散在PLA基体中; 在偏光显微镜下能观察到CNTs起到成核剂的作用, 明显细化了晶粒; 加入少量的酸化CNTs能够提高CNTs/PLA复合材料导电性, 体积电阻率下降了7个数量级; 同时, 酸化CNTs能够提高CNTs/PLA复合材料的降解性。     

碳纳米管增强镁基复合材料强化机制的解析法研究

采用剪切滞后模型理论分析了碳纳米管增强镁基复合材料受载时作用在复合材料上各组分的应力;考虑复合材料各种强化机制,建立碳纳米管增强镁基复合材料的屈服强度模型,研究了各组分性能参数对复合材料屈服强度的影响。结果表明,CNTs的长度对CNTs/Mg复合材料屈服强度的影响有限;碳纳米管层数越多或分散越稀疏越不利于提高复合材料的屈服强度;在一定范围内屈服强度随着温度差的增加而增加;CNTs的体积分数对复合材料屈服强度的影响存在最佳值。这表明该模型预测的复合材料屈服强度与实验结果较吻合。     

不同物相电沉积CNTs对C/SiC复合材料力学性能的影响

采用电沉积法与化学气相渗透(CVI)法将碳纳米管(CNTs)分别引入到碳纤维表面和SiC基体中,制得了不同物相电沉积CNTs的C/SiC复合材料(CNTs-C)/SiC和C/(CNTs-SiC)。研究了CNTs沉积物相对C/SiC复合材料力学性能的影响,分析了不同CNTs沉积物相的C/SiC复合材料的拉伸强度及断裂机制。结果表明:相较于未加CNTs的C/SiC复合材料,CNTs沉积到碳纤维表面的(CNTs-C)/SiC复合材料的拉伸强度提高了67.3%,断裂功提高了107.2%;而将CNTs引入到SiC基体中的C/(CNTs-SiC)复合材料的断裂功有所降低,拉伸强度也仅提高了6.9%,CNTs没有表现出明显的增强增韧效果;C/(CNTs-SiC)复合材料与传统的C/SiC复合材料有相似的断裂形貌特征,断裂拔出机制类似,主要为纤维增强增韧,CNTs的作用不明显。