碳纳米管束与炭黑并用对天然橡胶导热性能和动态力学性能的影响

研究不同长径比的多壁阵列碳纳米管束（carbon nanotube bundles,CNTBs）非等量替代炭黑N234并用的填料增强体系对天然橡胶（NR）导热性能和动态力学性能的影响。利用非线性拟合分析CNTBs管径与CNTBs/N234并用NR复合材料热导率的关系,发现随着CNTBs管径的减小和用量的提高,复合材料导热性能逐步提高。通过表征CNTBs在橡胶基体中形成的填料网络,发现CNTBs长径比增大和用量提高会导致杂化填料的分散效果下降即出现Payne效应,使复合材料在动态工况下损耗增大,60℃下7%应变的tanδ和疲劳温升出现增加。此外,添加长径比更大的CNTBs能提升材料的抗湿滑性能,提高玻璃化转变温度,但对磨耗性能有不利影响,CNTBs添加量为6 phr（相对于每100份以质量计量的橡胶添加的份数）时材料的磨耗体积显著增大。     

偶联剂/白炭黑补强体系对天然橡胶硫化和力学性能的影响

研究4种偶联剂KH-560,KH-570,Si-69,C800与白炭黑补强体系在天然橡胶(natural rubber,NR)中的应用,同时探讨偶联剂的种类和用量对NR硫化胶性能的影响.结果表明:随着偶联剂用量的增加,硫化时间缩短,其中偶联剂C800与白炭黑共混提高了NR硫化胶的抗焦烧性能,改善了加工性能;不同的偶联剂对硫化胶的力学性能有不同程度的提高,其中偶联剂KH-560与白炭黑共混增强NR力学性能的效果最好,当KH-560用量为2份时,胶料的力学性能达到最佳效果.     

混炼插层法制备天然橡胶/蒙脱土纳米复合材料

采用有机改性蒙脱土和新型补强性促进剂，通过混炼插层法制备了天然橡胶／蒙脱土纳米复合材料，用X射线衍射和透射电镜表征了纳米复合材料的结构和形态，用表观交联密度测定和红外光谱研究了蒙脱土与橡胶的相互作用，同时用X射线衍射法研究了混炼和硫化过程中天然橡胶分子链对蒙脱土的插层过程．结果表明，蒙脱土在橡胶基体中以纳米级厚度片层分散；补强性促进剂能加强蒙脱土与橡胶间的结合；天然橡胶分子链在混炼过程中便开始对蒙脱土进行插层，并主要在焦烧时间前的硫化诱导期内完成大部分插层过程，硫化开始后蒙脱土的纳米级分散进一步完善，直至硫化完成．添加2％～10％有机蒙脱土的天然橡胶／蒙脱土纳米复合材料的力学性能和动态力学性能优于40％N770炭黑补强的硫化胶．     

聚对苯二甲酸丙二酯/蒙脱土纳米复合材料的制备与表征

用原位缩聚的方法合成聚对苯二甲酸丙二酯／蒙脱土纳米复合材料(PTT／MMT)，所得的材料为剥离型纳米复合材料．通过DSC等测试手段研究了PTT／MMT纳米复合材料的结晶行为和热分解过程；测定了纳米复合材料的力学性能．结果表明，随着蒙脱土含量的增加，PTT／MMT的熔融结晶温度增高，其结晶过程为异相成核；纳米复合材料的力学性能有一定的提高．     

纳米氧化锌/聚对苯二甲酸乙二酯复合材料的原位制备及表征

利用原位聚合法制备了纳米ZnO/PET复合材料.讨论了纳米粒子分散剂的用量问题.用DSC分析手段分析了复合材料的热学性能,并测定了复合材料的力学性能.结果表明复合材料的冷结晶温度向高温方向移动,直观上说明纳米粒子阻碍了PET的结晶,但其力学性能且得到较大提高,尤其是试样拉伸性能得到显著提高.     

硫酸钙晶须的制备及其改性聚丙烯性能的研究

在不同反应条件下制备了不同长径比的硫酸钙晶须(CSW),利用硅烷偶联剂KH550(相对于CSW质量的2%)在110 ℃下对CSW进行干法改性.以硫酸钙晶须作为增强改性剂制备了PP/CSW复合材料.力学性能与差示扫描量热分析(DSC)结果表明:不同长径比的CSW对PP的力学性能和结晶性能均有提高;采用平均长径比为29的CSW添加剂,当添加的质量分数为20%时,复合材料的拉伸强度、弯曲模量分别比纯PP的提高了11%、104%;结晶温度比纯PP的提高了12 ℃;几种CSW对复合材料的热稳定性和耐热性都有改善,且随着CSW质量分数的增加,材料的热稳定性和耐热性提高越显著.     

钨含量和颗粒形状对钨合金力学性能的影响

采用MTS810材料疲劳实验系统,开展了不同粒径91钨合金材料的准静态单轴拉伸实验研究,获得了材料的应力应变曲线和静态力学性能参数。在此基础上,建立了能够反映钨合金材料宏微观特征的计算模型,数值计算了不同颗粒形状、不同钨含量合金材料在准静态拉伸载荷作用下的力学性能。得到了其整体的应力应变曲线以及钨合金屈服强度与钨合金微观参量之间的关系。并分析了钨合金材料的内部应力和应变场。结果表明:计算结果和实验结果吻合较好,随着钨含量的增加,钨合金的屈服强度增加,但其延伸率均降低;随着长径比的增加,钨合金的屈服强度有所增加,且随着长径比的增加,屈服强度的增加变得缓慢。为进一步钨合金材料性能的研究提供了重要的指导作用。     

聚（ε-己内酯）／纳米CaCO3复合材料结构与性能的研究

用熔融共混法制备了聚己内酯(PCL)／纳米CaCO3复合材料，考察了纳米CaCO3对PCL结晶性能和CaCO3含量对PCL／CaCO3复合材料力学及形状记忆性能的影响。DSC结果显示纳米CaCO3对PCL的成核结晶有一定的促进作用，辐照交联使PCL的结晶熔融温度和开始结晶温度提高5℃以上；DMA结果显示复合材料的模量随纳米CaCO3含量增加而增大，但高于40％后基本无变化。纳米CaCO3含量在5％～15％范围内能明显提高PCL的拉伸强度、弯曲强度和杨氏模量；辐照交联也起到增强各组分复合材料力学性能的作用，其变化的规律与交联前一致。复合材料经辐照交联后具有形状记忆特性，随着纳米CaCO3含量的增加，形变后的材料在熔融温度下开始回复所需时间缩短，回复速率加快，所有组成的样品在所测试的实验条件下最终回复率达97％以上。扫描电子显微镜观察表明纳米CaCO3粒子在PCL基质中无明显团聚现象。     

水泥砂浆应变率效应研究

为分析试件长径比和应变率对水泥砂浆动态力学性能的影响规律,采用准静态实验测量了砂浆的单轴压缩强度、弹性模量以及泊松比.利用分离式SHPB压杆进行1维应力压缩实验,对水泥砂浆试件进行了回收和比较,获得了不同长径比水泥砂浆试样在不同加载速率下的动态损伤破坏过程和应力应变曲线,研究了动态强度增强因子随应变率的变化规律.结果表明:动态压缩强度随应变率的增加而显著增大;试件直径相同时,厚度小的获得的动态强度增强因子要小于厚度大的;随着应变率提高,试件损伤增加,碎块尺寸越小,表明破坏能量随应变率的增加而提高.      

碳纳米管增强镁基复合材料长径比对力学性能影响的有限元分析

建立复合材料中(镀铜)碳纳米管增强镁基复合材料空间轴对称分析模型,直接采用有限元法研究长径比对纳米复合材料的力学性能的影响.研究表明,长径比较高时,增强基应力集中程度较高,饱和应力范围较大,说明提高长径比可以提高应力传递效率,有利于增强基高弹性模量的发挥;随着长径比的提高,复合材料整体弹性模量增大,当长径比超过临界值后整体弹性模量趋于稳定;对于碳纳米管增强镁基复合材料,长径比临界值为45,弹性模量的临界值为49 GPa.     

碳纳米管/天然橡胶复合材料的物理性能

为拓展碳纳米管应用领域,开发新型橡胶纳米复合材料,在碳纳米管预处理基础上,通过机械混炼方法将碳纳米管与天然橡胶复合。研究表明,与传统炭黑增强样品相比,碳纳米管在橡胶中的混入速度快,温升幅度小,混炼胶的硫化返原现象减轻。经过分散粘合体系处理,碳纳米管在橡胶中的分散性及界面粘合状况改善,热处理后复合材料的整体力学性能提高,对比炭黑增强样品,碳纳米管复合材料的弹性模量和玻璃化转变温度高,回弹及动态压缩性能好,并且热稳定性较高。     

Influences of poly (vinyl alcohol) molecular weight and carbon nanotubes on radiation crosslinking shape memory polymers

Polyvinyl alcohol (PVA) of two molecular weights was used to prepare shape memory polymers based on chemical-crosslinking by glutaraldehyde. The chemical-crosslinking was done in the presence of 2-carboxyethyl acrylate oligomers (CEA) and nano-filler [multi-wall carbon nanotubes (MWCNT) and functionalized carbon nanotubes (MWCNT-NH2)] followed by radiation-induced crosslinking. The analysis of the material revealed an increase in the gel fraction and a significant reduction in swelling of the nanocomposite material that was crosslinked with both glutaraldehyde and ionizing radiation. The radiation crosslinked nanocomposites demonstrated approximately a 90% gelation over a range of 50–300 kGy irradiation doses. The scanning electron microscopy (SEM) analysis showed a homogeneous distribution of nanocomposites in the composite matrix. The thermal properties of radiation crosslinked (PVA/CEA) and (PVA-CEA)-nano-fillers were investigated by a thermogravimetric analysis (TGA). The mechanical properties were examined via dynamic mechanical analysis (DMA) which showed significant variation because of the addition of nanocomposites. This radiation crosslinked materials show good shape memory behavior that may be useful in many applications based on the range of temperatures at which Tan δ appears.     

Enhancement of the thermo-mechanical properties and efficacy of mixing technique in the preparation of graphene/PVC nanocomposites compared to carbon nanotubes/PVC

Thin films of poly vinyl chloride(PVC)/multiwalled carbon nanotubes(MWCNT) and PVC/graphene(GN) nanocomposites were prepared by mixing in the presence of different quantities of nanoparticles. Film casting was performed using tetrahydrofuran as a solvent. The as-prepared PVC/MWCNT and PVC/GN nanocomposites were characterized by scanning electron microscopy, Raman spectroscopy, X-ray diffraction,thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and diffused reflectance spectroscopy. Only the PVC/GN nanocomposite films were evaluated further for detailed mechanical analysis because of the poor dispersion of MWCNTs in PVC. The PVC/GN nanocomposite films were thermo-mechanically more stable than the PVC films. These nanocomposites have potential as a replacement material for PVC and PVC/MWCNT owing to their better dispersion and high stability.     

Enhancement of the thermal and mechanical properties of polyurethane/ polyvinyl chloride blend by loading single walled carbon nanotubes

Structural, thermal, and mechanical properties of pure blend and nanocomposites based on polyurethane (PU) and polyvinyl chloride (PVC) doped with low different content of single walled-carbon nanotubes (SWCNTs) were studied. The nanocomposites at different concentration were prepared via casting technique. The interaction between PU/PVC and CNTs were examined via FT-IR studies. The changes in the structures of the nanocomposites were examined using X- Ray Diffraction (XRD), and the results indicated that the amorphous domains of nanocomposites increased with increasing SWCNTs content. Transmission electron microscope (TEM) observation indicated that SWCNTs surface was wrapped with the polymer with the thermal properties of nanocomposites improved. The mechanical behavior of the nanocomposites was evaluated as a function of SWCNTs content. The main enhancement in tensile properties was observed, e.g., the tensile strength and elastic modulus increased compared with the pure blend, which may be attributed to the interaction and adhesion between CNTs and the polymer matrices due to the hydrogen bonding between carbonyl groups (C=O) of polymer blend chains and carboxylic acid (COOH) groups of CNTs.     

复合添加炭黑对低碳铝碳材料显微结构与性能的影响

以板状刚玉颗粒、活性氧化铝微粉、Si粉为主要原料,以N220或N990炭黑为碳源,以热固性酚醛树脂为结合剂,在埋炭条件下制备低碳铝碳材料,研究添加不同炭黑对所制得试样显微结构、抗折强度及热震稳定性的影响。结果表明,添加N220炭黑有利于促进材料的致密化和有效发挥纳米炭黑粒子对热应力的吸收作用,降低热冲击对材料结构的破坏,而添加N990炭黑有助于改善铝碳材料的孔结构,有利于试样在高温下形成长径比更大的碳化硅晶须,从而提高材料的力学性能;复合添加N220、N990炭黑能提高低碳铝碳材料试样的强度和抗热震性。材料热震后的抗折强度为7.44 MPa、残余强度保持率为53%~62%。     

Freestanding single-walled carbon nanotube bundle networks: Fabrication, properties and composites

As a type of thin film, two dimensional (2D) reticulate architectures built of freestanding single-walled carbon nanotube (SWCNT) bundles are suitable for scalable integration into devices and nanocomposites for many applications. The superior properties of these films, such as optical transparency, unique electrical properties and mechanical flexibility, result not only from the outstanding properties of individual SWCNTs but also from the collective behavior of the individual tubes, with additional properties arising from the tube-tube interactions. In this review, the synthesis, structure and fundamental properties, such as conductivity, transparency, optical nonlinearity and mechanical performance, of ??freestanding SWCNT bundle network?? thin films and nanocomposites, as well as their application as supercapacitors are highlighted. Some long-standing problems and topics warranting further investigation in the near future are addressed.     

小麦麸质-针形硅酸盐纳米复合材料的制备与性能

通过湿法工艺在小麦麸质中加入一定量的凹凸棒,经冷冻干燥和热模压方法制备了小麦麸质-凹凸棒纳米复合材料.研究发现:凹凸棒在小麦麸质中能均匀分散,且当凹凸棒质量分数为7%时,复合材料拥有较好的力学性能.同时,不同复合材料的降解实验结果表明,该复合材料在土中埋10 d后,质量降解为原来的50%,20 d后只剩下原来的20%左右.通过在小麦麸质中加入凹凸棒所得到的复合材料提高了小麦麸质的力学性能,是一种可降解复合材料.     

累积叠轧焊工艺改善普碳钢材料性能特征

在普通热轧机上利用累积叠轧焊工艺对普碳钢Q235进行了实验研究,重点研究了压下量(最大压下量98%)、循环轧制次数等工艺参数对Q235钢组织及性能的影响规律.结果表明:在普通热轧机上应用累积叠轧焊工艺对同种材料进行焊合,不仅可以获得连续、均匀的结合组织,而且使Q235钢的组织得到明显的细化,夹杂物分布更加均匀,材料的强度大幅度提高,抗拉强度达800MPa以上.     

Chemical,mechanical, and thermal expansion properties of a carbon nanotube-reinforced aluminum nanocomposite

In the present study, the chemical and mechanical properties and the thermal expansion of a carbon nanotube (CNT)-based crystalline nano-aluminum (nano Al) composite were reported. The properties of nanocomposites were tailored by incorporating CNTs into the nano Al matrix using a physical mixing method. The elastic moduli and the coefficient of thermal expansion (CTE) of the nanocomposites were also estimated to understand the effects of CNT reinforcement in the Al matrix. Microstructural characterization of the nanocomposite reveals that the CNTs are dispersed and embedded in the Al matrix. The experimental results indicate that the incorporation of CNTs into the nano Al matrix results in the increase in hardness and elastic modulus along with a concomitant decrease in the coefficient of thermal expansion. The hardness and elastic modulus of the nanocomposite increase by 21% and 20%, respectively, upon CNT addition. The CTE of CNT/Al nanocomposite decreases to 70% compared with that of nano Al.