机械混炼对碳纳米管/丁苯橡胶复合材料的影响

为研究机械混炼对碳纳米管(CNTs)/粉末丁苯橡胶(SBR)复合材料性能的影响,从而获得性能优异的CNTs/SBR复合材料,联合采用喷雾干燥法和机械混炼法,制备高填充量CNTs/SBR复合材料.将喷雾干燥法制备的CNTs/粉末SBR复合材料在开炼机上机械混炼,对比分析混炼前后试样的物理和力学等相关性能,并对其微观形貌进行检测.结果表明,机械混炼使CNTs获得进一步的分散,与SBR基体间作用力得到增强,与混炼前相比,混炼后试样的玻璃化转变温度、交联度和常规力学性能均得到提高,当CNTs加入量为50phr时,混炼后复合材料的拉伸强度和撕裂强度分别为13.1MPa和39.8kN/m,比混炼前试样分别提高了约80%和20%.     

预拉伸对聚丁二酸丁二醇酯/碳纳米管复合材料结晶行为及力学性能影响

以熔融共混法制备了碳纳米管(CNTs)增强的聚丁二酸丁二醇酯(PBS)复合材料,研究了预拉伸对PBS/CNTs复合材料结晶行为及力学性能的影响。CNTs的加入在复合材料中起到了异相成核作用,促进了PBS的结晶,提高了复合材料的力学性能。单轴预拉伸使CNTs与PBS分子链的有序程度同时增加,有序排列的CNTs进一步增加了PBS晶体的取向度,预拉伸与CNTs对复合材料的增强实现了协同作用。然而,加入CNTs以及在不同温度、不同拉伸应变下的预拉伸均未导致PBS晶体结构发生转变。经在60℃预拉伸500%的PBS/CNTs (质量分数5%)复合材料,其拉伸强度达到286.1 MPa、弹性模量达2.9 GPa,实现了对PBS的增强。     

纳米粘土/炭黑双相填料对天然橡胶性能的影响

以有机纳米粘土替代部分炭黑,在材料内部引入形状各向异性的纳米片层,制备天然橡胶/炭黑/纳米粘土复合材料,研究了粘土含量对复合材料静态力学性能、动态力学性能、热稳定性、老化性及拉伸疲劳性能的影响。结果表明,以少量有机纳米粘土(2 phr～6 phr)替代部分炭黑可提高天然橡胶的硫化效率,增强复合材料的静态力学性能,降低动态损耗因子,提高复合材料的热稳定性、耐热空气老化性能及拉伸疲劳性能。与纯炭黑试样相比,复合材料拉伸强度最高提高91%,拉伸疲劳寿命提高31%,达55万次。     

包装箱用混杂纤维复合材料的设计

目的 研究混杂纤维复合材料在静载荷作用和拉-拉疲劳载荷条件下的力学性能及其在包装箱等领域的应用。方法 采用树脂转移模塑成型工艺制备5种包装箱用混杂纤维复合材料,并对试样进行拉伸性能和拉-拉疲劳性能测试。结果 纯C试样的拉伸强度高于C/G层内和C/G层间试样;在相同的铺层和织布方式下,C/G层内试样的拉伸强度高于C/G层间试样;纯G试样的塑性明显优于C/G层内和C/G层间试样,C/G层内试样的断裂伸长率高于C/G层间试样;C/G层内试样具有混杂正效应,可保证在具有较高强度的同时具备良好塑性。玻璃纤维在提高复合材料料板疲劳寿命上的作用要高于芳纶纤维,前者的刚度退化会低于后者,且碳纤维和玻璃纤维的层内混杂方式要优于层间混杂,层间混杂在复合材料抵抗疲劳损伤时具有正混杂效应。     

两步偶氮反应法制备碳纳米管/碳纤维杂化增强体

采用两步偶氮反应的方法,在碳纤维(CF)表面成功接枝上碳纳米管(CNTs),制得多尺度杂化材料CNTs/CF。采用扫描电子显微镜电镜(SEM)对样品表面进行观察,发现CNTs均匀分布在CF表面。用X射线光电子能谱仪(XPS)对样品的表面化学组成进行了分析,发现CNTs接枝在了CF表面。并通过单丝拉伸实验对样品进行测试,和CF相比,CNTs/CF的拉伸强度为3.4GPa,模量为220GPa,比CF有轻微的降低,说明这种接枝方法有效保护了CF的力学性能。     

CF/PPEK、CF/PPES复合材料高温力学性能研究

采用预浸热压成型工艺制备碳纤维增强杂萘联苯聚醚酮(CF/PPEK)和碳纤维增强杂萘联苯聚醚砜(CF/PPES)单向复合材料试样,通过对试样在常温和高温条件下的力学性能测试与分析,研究了高性能热塑性复合材料在高温条件下力学性能及其强度和模量保留率的变化规律.实验表明,在250℃下其拉伸和弯曲强度及模量的保留率均在60%以上,仍具有极高的承载能力.利用Tr-n预测模型对这两种复合材料高温力学性能进行的预测结果与试验值基本吻合,从而验证了这个模型的可行性.     

基于碳纳米管界面改性的碳纤维复合材料抗γ辐射性能研究

为研究碳纳米管(CNTs)界面改性对碳纤维/环氧复合材料(CF/EP)抗辐照性能的影响,采用电泳沉积法将CNTs引入到CF/EP界面区域(CF-CNTs/EP)中,然后分别对CF/EP和CF-CNTs/EP进行γ射线辐照处理(γ-CF/EP和γ-CF-CNTs/EP),并对复合材料的力学性能、热学性能、耐疲劳性能和官能团变化等特性进行分析。结果表明:由于CNTs的存在,γ-CF-CNTs/EP的储能模量、玻璃化转变温度、弯曲强度和弯曲模量分别比γ-CF/EP高7. 8 GPa、4. 53℃、280 MPa和19. 2 GPa;γ-CF-CNTs/EP的耐疲劳性能优于γ-CF/EP; XPS测试发现γ-CF-CNTs/EP内部C-C键的含量急剧减少10. 88%,C-N键和C-O键的含量分别增加5. 97%和4. 44%,而γ-CF/EP无明显变化。结合断面形貌分析和裂纹扩展模型,讨论了CNTs增强复合材料抗γ射线辐射的微观结构和增强机制。以上结果证实,CNTs界面区域改性可以有效提升CF/EP的抗辐射性能。     

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。     

氯化聚乙烯/碳纳米管复合材料的制备及其性能研究

以三氯化铝(AlCl3)作催化剂,将多壁碳纳米管(MWNTS)悬浮在氯仿(CHCl3)溶液中,通过亲电加成反应,对MWNTS进行了侧壁化学修饰,并对化学修饰后的MWNTS作了红外光谱的分析.分别采用机械共混法和溶液共沉淀法制备了CPE/CNTs复合材料,对CPE/CNTs复合材料进行了拉伸性能及流变性能的测试,并利用扫描电子显微镜(SEM)观察了CPE/CNTs复合材料拉伸断面的形貌特征.结果表明:CPE/CNTs复合材料的拉伸强度随碳纳米管加入量的增加而增大,当碳纳米管的加入量为5份时,其拉伸强度最大,与纯氯化聚乙烯的拉伸强度相比,提高了75%;化学修饰后的碳纳米管在氯化聚乙烯基体中有了较好的分散性和相容性;CPE/CNTs复合材料的表观粘度随碳纳米管加入量的增加而逐渐增大.     

碳纤维增强热塑性聚酰亚胺及其复合材料

采用双螺杆共混挤出法,在热塑性聚酰亚胺(TPI)树脂中添加碳纤维(CF)进行复合增强,实验研究了碳纤维种类、加入量及成型方法对复合材料力学性能的影响.结果表明:碳纤维的加入能显著提高材料的常温和高温力学强度,并与碳纤维种类有关;复合材料的拉伸和弯曲强度均随着碳纤维加入量的增大而升高;相对于模压成型方法,注塑成型可获得更高强度的复合材料.由扫描电镜(SEM)观察到的材料拉伸和弯曲断面的微结构形貌,初步探讨了碳纤维的增强机理.     

Kinetics of chemical vapor infiltration of carbon nanofiber-reinforced carbon/carbon composites

Preforms containing 0, 5, 10, 15 and 20 wt.% carbon nanofibers (CNFs) were fabricated by spreading layers of carbon cloth, and infiltrated by using the technique of isothermal chemical vapor infiltration (ICVI) at the temperature of 1100 °C under the total pressure of 1 kPa and with the flow of the mixture of propane/nitrogen in a ratio of 13:1. The infiltration rates increased with the rising of CNF content, and after 580 h of infiltration, the achievable degree of pore filling was the highest when the CNF content was 5 wt.%, but the composite could not be densified efficiently as the CNF content ranged from 10 to 20 wt.%. An analysis of the results, based on the effective diffusion coefficient and on the in-pore deposition rates, shows that the CNFs, due to their higher aspect ratio, accelerate overgrowth at pore entrances and thus lead to incomplete pore filling.     

短切炭纤维增强沥青基C/C复合材料的力学性能

利用模压半炭化成型工艺在大气环境下制备出了短切炭纤维增强沥青基C／C复合材料（简称SCFRC）。研究了短切炭纤维的体积分数对SCFRC材料的体积密度和力学性能的影响规律。借助光学显微镜和扫描电镜对其微观组织和断口形貌进行了观察，分析了短切炭纤维对SCFRC材料的增强机制。结果表明，当短切炭纤维的体积分数由0％增大到11．8％时，SCFRC材料的力学性能随之呈线性增加；短切炭纤维增强SCFRC材料的机制主要有裂纹偏转效应、桥联效应以及脱粘和拔出效应。     

短切炭纤维增强沥青基C/C复合材料的组织特征

利用新型、高效的模压半炭化成型工艺，在大气环境下制备出了短切炭纤维增强沥青基C／C复合材料制品，并借助光学显做镜和扫描电镜对其微观组织和断口形貌进行了观察。通过分析，解释了短切炭纤维增强沥青基C／C复合材料中炭纤维损伤的形成机制，提出了作为增强体相的短切炭纤维和焦炭颗粒与基体炭之间独特的界而结构模型。研究还表明：复合材料中明显存在着基体相和颗粒相一基体相的显微结构不仅呈层片状，而且层片状的结构好像数层桔子皮，将颗粒相包裹起来，这种“桔皮包裹”式的结构与炭纤维表面的POG结构基本相似。     

Graphitization behaviour of carbon fibre-glassy carbon composites

Carbon fibre-carbon composites were fabricated by aligning PAN-based carbon fibre unidirectionally in furfuryl alcohol resin char. The graphitization behaviour was investigated by an X-ray diffraction technique and by the measurement of magnetoresistance. The time-temperature superimposition study for interlayer spacing resulted in an activation energy of 242±35 kcal mol⁻¹. The kinetic study on magnetoresistance agreed with the result of X-ray measurement. The activation energy is that for the graphitization of the layer structure formed in the glassy carbon matrix of the composites. The graphitization mechanism of the layer structure is the same as that of soft carbons.     

软硬混编预制体增强沥青基4D-C/C材料的拉伸破坏行为

以X-Y平面依次铺设炭纤维束、Z向穿插炭棒的4D软硬混编为预制体,采用沥青液相常压、高压浸渍/炭化-石墨化循环致密工艺制备4D-C/C复合材料。通过该材料Z向(炭棒方向)的拉伸实验,测定其拉伸性能和力学行为,并采用SEM分析试样表面及断口形貌。结果表明:宏观上拉伸试样以炭棒整体拔出的形式破坏;细观尺度上,试样表面形成了与载荷方向垂直的贯穿性裂纹,裂纹以2 mm左右的距离呈等间距分布;材料进一步的破坏过程中,基体裂纹在X-Y向纤维束中呈线性扩展,快速分割了基体材料,使4D-C/C复合材料的拉伸破坏演变为1D-C/C复合材料的破坏模式,由于炭棒与基体炭界面结合弱,炭棒以拔出方式失效和破坏。     

Mesoscale evolution of non-graphitizing pyrolytic carbon in aligned carbon nanotube carbon matrix nanocomposites

Polymer-derived pyrolytic carbons (PyCs) are highly desirable building blocks for high-strength low-density ceramic meta-materials, and reinforcement with nanofibers is of interest to address brittleness and tailor multi-functional properties. The properties of carbon nanotubes (CNTs) make them leading candidates for nanocomposite reinforcement, but how CNT confinement influences the structural evolution of the PyC matrix is unknown. Here, the influence of aligned CNT proximity interactions on nano- and mesoscale structural evolution of phenol-formaldehyde-derived PyCs is established as a function of pyrolysis temperature (\(T_{\mathrm {p}}\)) using X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy. Aligned CNT PyC matrix nanocomposites are found to evolve faster at the mesoscale by plateauing in crystallite size at \(T_{\mathrm {p}}\) \(\sim\)800 \(^{\circ }\hbox {C}\), which is more than \(200\,\,^{\circ }\hbox {C}\) below that of unconfined PyCs. Since the aligned CNTs used here exhibit \(\sim\)80 nm average separations and \(\sim\)8 nm diameters, confinement effects are surprisingly not found to influence PyC structure on the atomic-scale at \(T_{\mathrm {p}}\) \(\le \)1400 \(^{\circ }\hbox {C}\). Since CNT confinement could lead to anisotropic crystallite growth in PyCs synthesized below \(\sim\)1000 \(^{\circ }\hbox {C}\), and recent modeling indicates that more slender crystallites increase PyC hardness, these results inform fabrication of PyC-based meta-materials with unrivaled specific mechanical properties.     

Co-synthesis of single-walled carbon nanotubes and carbon fibers

A new vertical floating catalytic technique is developed and used to prepare both single-walled carbon nanotubes (SWNTs) and carbon fibers (CFs). Scanning electron microscopy (SEM) observation shows a clear separation of these two materials. Thin films of SWNTs can be peeled easily from the CF substrate which just acts as a catalyst support for the SWNT growth. The production process is also semicontinuous, resulting in a yield of ∼1.0 g h⁻¹ of SWNTs film with high purity. Structure and vibrational properties of these materials are investigated by electron microscopy and Raman spectroscopy, respectively.     

Vitreous carbon — A new form of carbon

The carbonisation of certain cross-linked polymers under carefully controlled conditions yields a non-graphitising carbon which, on account of its high lustre and conchoidal fracture, has been called vitreous carbon. Other properties distinguishing vitreous carbon from the more common forms of the element include high strength, hardness, and resistance to corrosion, with low porosity and permeability. It has advantages over other materials of construction in a wide range of laboratory, metallurgical, mechanical, and electrical applications.     

碳/碳复合材料的应用研究进展

综述了碳/碳(C/C)复合材料的性能及其在各个领域的应用现状.