尼龙6/碳纳米管纳米复合材料自由体积特性的正电子湮没研究

采用正电子湮没寿命谱技术研究了尼龙6/碳纳米管纳米复合材料的自由体积特性。实验结果发现碳纳米管对纳米复合材料的自由体积孔洞尺寸影响甚微,而自由体积孔洞数目和相对自由体积分数均随碳纳米管含量的增加而明显减小。导致这种减小的原因可能来自两方面,其一是由于碳纳米管和基质聚合物间的相互作用限制了高分子链段运动;其二是碳纳米管填充增强了尼龙6基体结晶性能。此外,力学性能研究表明,碳纳米管在复合材料中较均匀的分散和较好的界面接触可以提高材料的力学强度,而自由体积分数的减小则使材料的韧性变差。     

聚氨酯弹性体/蒙脱土纳米复合材料的合成与性能

采用聚氨酯本体预聚法 ,利用原位插层聚合合成了聚氨酯 蒙脱土纳米复合材料 .通过X 射线衍射(XRD)和Molau实验研究了蒙脱土在复合材料中的分散情况 .红外分析 (IR)表明随着蒙脱土含量的增加 ,复合材料羰基氢键减少 .动态力学分析 (DMA)以及差热分析 (DSC)结果说明随着蒙脱土含量的增加 ,材料的玻璃化温度降低 .聚氨酯纳米复合材料的拉伸强度和断裂伸长率同时提高 ,表现出较好的力学性能 .     

新型沥青基ACNT/C纳米复合材料的制备与表征

以超长定向碳纳米管(ACNTs)阵列为骨架，中温煤焦油沥青为浸渍剂，采用浸渍-炭化工艺经过一个循环制备了密度约为1.25 g·cm^-3的沥青基定向碳纳米管/炭(ACNT/C)纳米复合材料。采用扫描电子显微镜(SEM)、偏光金相显微镜(PLM)、X射线衍射(XRD)和Raman光谱分析对这种新型纳米炭材料进行了表征。结果表明ACNT/C中沥青炭为明显的各向异性组织，以碳纳米管为核心形成了非常细密的流线型层片结构，具有较高的晶化程度。采用热失重分析(TGA)方法考察了材料在空气中的热稳定性能，发现ACNT/C纳米复合材料在空气中的热失重初始温度比相同工艺条件下，以炭纤维为骨架制备的密度相近的炭/炭(C/C)复合材料提高了50 ℃左右。     

吸附共沉淀法制备聚醚醚酮/多壁碳纳米管复合材料与性能研究

通过吸附共沉淀法均匀混合聚醚醚酮(PEEK)粉末和经过表面改性的多壁碳纳米管(MWCNT),再经注塑加工成功地制得PEEK/MWCNT复合材料(PM)。SEM观察结果显示,该复合法使得MWCNT在PEEK中均匀分散且与PEEK有较好的结合力。力学测试结果表明,MWCNT含量为6%的PM其弯曲强度提高20%左右,拉伸强度提高10%。MWCNT的加入使得复合材料的结晶温度和熔融温度均有一定提高。     

改性多壁碳纳米管/聚乳酸复合材料的研究

制备了改性多壁碳纳米管/聚乳酸复合材料,研究了改性多壁碳纳米管对聚乳酸的增强作用.通过拉曼光谱分析、热重分析证实了多壁碳纳米管酸化酯化反应的发生.通过溶液法制备了聚乳酸/改性多壁碳纳米管复合物.考察了聚乳酸和改性多壁碳纳米管复合体系的相容性.扫描电镜分析结果说明了聚乳酸和改性多壁碳纳米管复合物相容性的变化.随着改性多壁碳纳米管在复合物中含量的增加,体系的分散效果也越好,相容性也有提高.实验结果表明,在聚乳酸材料中添加改性碳纳米管材料到一定值对,可以提高材料的力学性能,且当改性碳纳米管添加量达到1.5％的时候材料力学性能达到了一个最大值,拉伸强度可达120.4MPa.     

多壁碳纳米管-环氧树脂纳米复合材料的γ-射线固化行为

通过γ-射线辐射固化制备了多壁碳纳米管-环氧树脂复合材料.采用索氏提取法、傅里叶变换红外光谱(FT-IR)和差示扫描量热法(DSC)测试了多壁碳纳米管-环氧树脂复合体系的凝胶含量、转化率及热流曲线等固化动力学参数.采用扫描电子显微镜(SEM)表征了复合材料的微观组织.结果表明:通过γ-射线辐射固化的复合体系的凝胶含量随着辐射剂量、光引发剂含量的增加而增加;由于多壁碳纳米管对活性反应中心的影响,转化率随着多壁碳纳米管加入量的增加呈先下降,后增加的趋势.复合体系中多壁碳纳米管含量较高时易发生团聚,团聚会对复合体系的固化行为产生一定影响.     

壳聚糖/氧化石墨烯纳米复合材料的形态和力学性能研究

通过溶液共混法成功制备了氧化石墨烯/壳聚糖纳米复合材料. 透射电镜(TEM)结果表明, 氧化石墨烯纳米粒子在壳聚糖基体中分散良好. 拉伸实验结果表明, 随氧化石墨烯含量的增加, 氧化石墨烯/壳聚糖纳米复合材料的杨氏模量和拉伸强度均显著改善, 加入4 wt%的氧化石墨烯能够使纳米复合材料的杨氏模量和拉伸强度分别提高123%和117%|但另一方面, 却也在一定程度上使复合材料的断裂伸长率或韧性下降.     

多壁碳纳米管/玻璃纤维/含邻苯二甲腈的苯并噁嗪树脂复合材料的电学与力学性质(英文)

采用溶液共混法及层压成型的方法制备了多壁碳纳米管/玻璃纤维/含双邻苯二甲腈的苯并噁嗪树脂复合材料,并考察了该纳米复合材料的力学及电学性质。材料的渗滤阀值为碳纳米管含量为0.7%,此时,材料也表现出最好的机械性能。通过扫描电镜对材料的断面进行了考察,发现在碳纳米管含量为0.7%时形成了网状结构,因此此时复合材料表现出最好的电学及力学性质。复合材料在碳纳米管含量低于7%时具有很低的吸水性。     

层状硅酸盐累托石/环氧树脂纳米复合材料的结构和性能研究

用有机改性的层状累托石与环氧树脂复合制备出纳米复合材料 .通过改变累托石含量发现在很低含量 (0 5W % )时纳米复合材料具有最佳力学和热学性能 ,冲击强度增加 12 0 % ,断裂伸长率增加 330 %玻璃化转变温度提高 2 8℃ .用X衍射、透射电镜和红外吸收光谱研究了材料的微观结构 ,结果表明层状累托石和环氧树脂发生了化学反应 ,观测到了层状累托石完全剥离和插层两种结构形态 ,且累托石含量较低时容易形成剥离型 .具有大的比表面积、高的反应活性的累托石片层分散于环氧基体中形成剥离型为主的结构有利于改善复合材料的力学性能并增加其热稳定性 .     

新型ACNT/C纳米复合材料氧化性能的初步研究

以定向碳纳米管阵列为骨架, 利用化学气相渗(CVI)工艺制备了新型的定向碳纳米管/炭(ACNT/C)纳米复合材料, 并对其氧化性能进行了初步的研究. SEM形貌观察表明, 氧化后的ACNT/C纳米复合材料仍然保持着其基本的管状结构特点, 氧化由外层热解炭向内逐渐进行. 热失重分析 (TGA)检测结果表明, 密度为0.80 g•cm-3的ACNT/C纳米复合材料在空气中的热失重转变温度约为720 ℃, 比相同工艺条件下制备的密度为1.5 g•cm-3的C/C复合材料提高了50 ℃左右. 静态空气等温氧化实验表明, ACNT/C纳米复合材料在550 ℃氧化过程中的化学反应速率明显低于C/C复合材料. 这主要是由于ACNT/C纳米复合材料具有稳定的界面和较高的晶化程度.     

Effect of the Nanotube Radius and the Volume Fraction on the Mechanical Properties of Carbon Nanotube-Reinforced Aluminum Metal Matrix Composites

By using the advantages of carbon nanotubes (CNTs), such as their excellent mechanical properties and low density, CNT-reinforced metal matrix composites (MMCs) are expected to overcome the limitations of conventional metal materials, i.e., their high density and low ductility. To understand the behavior of composite materials, it is necessary to observe the behavior at the molecular level and to understand the effect of various factors, such as the radius and content of CNTs. Therefore, in this study, the effect of the CNT radius and content on the mechanical properties of CNT-Al composites was observed using a series of molecular dynamics simulations, particularly focusing on MMCs with a high CNT content and large CNT diameter. The mechanical properties, such as the strength and stiffness, were increased with an increasing CNT radius. As the CNT content increased, the strength and stiffness increased; however, the fracture strain was not affected. The behavior of double-walled carbon nanotubes (DWNTs) and single-walled carbon nanotubes (SWNTs) was compared through the decomposition of the stress–strain curve and observations of the atomic stress field. The fracture strain increased significantly for SWNT-Al as the tensile force was applied in the axial direction of the armchair CNTs. In the case of DWNTs, an early failure was initiated at the inner CNTs. In addition, the change in the elastic modulus according to the CNT content was predicted using the modified rule of mixture. This study is expected to be useful for the design and development of high-performance MMCs reinforced by CNTs.     

Fabrication of Single Wall Carbon Nanotubes-Based Poly(vinyl butyral) Nanocomposites with Enhanced Mechanical and Thermal Properties

In this research, poly(vinyl butyral) (PVB)/single wall carbon nanotubes (SWCNT) composites were prepared via solution blending method. Dispersion degree of SWCNT in the composites was characterized by Scanning Electron Microscopy (SEM) and mechanical properties were measured with tensile testing. Thermal degradation of composites was investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). SEM analysis confirmed good dispersion of the nanotubes in the PVB. The tensile tests showed significant increases in mechanical properties such as exceptional improvement in tensile strength, Young's modulus and flexibility for the composites compared to PVB at low SWCNT content.The TGA curves indicated that adding SWCNT improved the thermal stability of the PVB significantly and the degradation of the polymer matrix shifted to the higher temperatures. For the sample containing 0.6 wt%, an increase of 171% in modulus and a 258.4% enhancement of tensile strength were achieved. Also, elongation at break increased 28.7% at this loading. In fact, intrinsic properties of nanotubes caused enhancement of strength and flexibility simultaneously. Also, for this composite, T_onset and T_max enhanced remarkably and weight loss reduced greatly and residue at 600°C increased to high values. These results are promising for application of the PVB in industry.     

碳纳米管/SnO2复合电极的制备及其电催化性能研究

采用液相沉积法制备碳纳米管(CNTs)/SnO₂复合材料, 并制备成电极, 分别与石墨/SnO₂及活性炭/SnO₂复合电极比较, 考察电催化降解有机废水的性能. 由于CNTs高的比表面积及优良的导电性能, 结合SnO₂良好的催化活性, CNTs/SnO₂复合电极电催化降解有机废水性能优越. 研究发现, CNTs的预处理情况、SnO₂负载量以及煅烧温度对复合电极的电催化性能有重要影响. 当功能化CNTs负载40% SnO₂, 煅烧温度600 ℃时, 所得CNTs/SnO₂复合电极电催化降解有机废水的能力是纯CNTs电极的2倍. 最后, 初步探讨了CNTs/SnO₂复合电极电催化降解有机废水的机理.     

碳纳米管对羟基磷灰石基复合材料力学性能的影响

将力学性能优良的碳纳米管(CNTs)与羟基磷灰石(HA)生物陶瓷相复合,发展CNTs/HA复合材料来应用于骨组织修复领域,有望解决HA生物陶瓷力学性能的不足.通过3种不同的制备方法,即通过表面活性剂将CNTs分散在HA基体中、通过酸碱中和反应将CNTs与HA共沉淀以及通过体外浸泡在CNTs上矿化生长HA等方法来获得CNTs/HA复合材料.深入研究CNTs的表面结构和分散状态对CNTs/HA复合材料力学性能的影响.结果表明,CNTs的添加改变了HA的脆性,导致复合材料抗压力学性能得到提高.但是,由于复合材料制备方法的不同,导致CNTs在HA基体中的分散状态、表面结构的完整性以及与HA的界面结合情况不同,导致其抗压力学性能不同.其中,通过表面活性剂将CNTs分散在HA基体中而获得复合材料的抗压力学性能表现最好,而CNTs与HA通过共沉淀法所获得复合材料的抗压力学性能表现最差.     

碳纳米管对羟基磷灰石基复合材料力学性能的影响

将力学性能优良的碳纳米管(CNTs)与羟基磷灰石(HA)生物陶瓷相复合,发展CNTs/HA复合材料来应用于骨组织修复领域,有望解决HA生物陶瓷力学性能的不足。通过3种不同的制备方法,即通过表面活性剂将CNTs分散在HA基体中、通过酸碱中和反应将CNTs与HA共沉淀以及通过体外浸泡在CNTs上矿化生长HA等方法来获得CNTs/HA复合材料。深入研究CNTs的表面结构和分散状态对CNTs/HA复合材料力学性能的影响。结果表明,CNTs的添加改变了HA的脆性,导致复合材料抗压力学性能得到提高。但是,由于复合材料制备方法的不同,导致CNTs在HA基体中的分散状态、表面结构的完整性以及与HA的界面结合情况不同,导致其抗压力学性能不同。其中,通过表面活性剂将CNTs分散在HA基体中而获得复合材料的抗压力学性能表现最好,而CNTs与HA通过共沉淀法所获得复合材料的抗压力学性能表现最差。     

Ultrahigh Molecular mass Polyethylene/ Carbon Nanotube CompositesCrystallization and melting properties

Ultrahigh molecular mass polyethylene (UHMMPE) is filled with carbon nano-tubes (CNTs) by solution in the presence of maleic anhydride grafted styrene-(ethylene-co-butylene)-styrene copolymer (MA-SEBS) as a compatibilizer. The UHMMPE/CNT composites crystallized from melt were prepared at a cooling rate of 20°C min^-1. The melting and crystallization behaviors of UHMMPE/ CNT composites were investigated by differential scanning calorimetry. The results showed that onset melting temperature (T _m) and degree of crystallinity (X _c) of UHMMPE/CNT composites crystallized from solution are higher than those from melt due to the larger crystalline lamellar thickness. The onset crystallization temperature (T _c) of UHMMPE/CNT composites tends to shift to higher temperature region with increasing CNT content in the composites. Tm and Tc of UHMMPE phase in UHMMPE/CNT composites decrease with the addition of MA-SEBS. Moreover, the crystallization rate of UHMMPE phase in UHMMPE/CNT composite is increased due to the introduction of CNTs. MA-SEBS acts as compatilizer, enhances the dispersion of CNTs in the UHMMPE matrix. Thereby, the crystallization rate of UHMMPE phase in UHMMPE/CNT composite is further increased with the addition of MA-SEBS. This revised version was published online in August 2006 with corrections to the Cover Date.     

Biocomposites based on Alfa fibers and starch‐based biopolymer

Biocomposite materials based on Alfa cellulose fibers (esparto grass plant) as reinforcing element and starch‐based biopolymer matrix were prepared and characterized in terms of mechanical performance, thermal properties, and water absorbance behavior. The fibers and the matrix were first mixed in the melted state under mechanical shearing using a plastograph and the obtained composites were molded by injection process. The tensile mechanical analysis showed a linear increase of the composite flexural and tensile modulus upon increasing the fiber content, together with a sharp decrease of the elongation at break. The fibers′ incorporation into the biopolymer matrix brings about an enhancement in the mechanical strength and the impact strength of the composite. Dynamic mechanical thermal analysis (DMTA) investigation showed two relaxations occurring at about ?30 and 35°C. The addition of Alfa fibers enhanced the storage modulus E′ before and after T_α, which is consistent with the reinforcing effect of Alfa cellulose fibers. Copyright © 2008 John Wiley & Sons, Ltd.     

The tensile properties of HNO3‐treated carbon fiber reinforced ABS/PA6 composites

In this study, acrylonitrile‐butadiene‐styrene (ABS) terpolymer was reinforced with HNO₃‐treated short carbon fibers (SCFs) [(hollow carbon fibers (HCFs)]. The effects of HCF concentration on the tensile properties of the composites were examined. Increasing the HCF concentration in the ABS matrix from 10 to 30 wt% resulted in improved tensile strength and tensile modulus. To obtain a strong interaction at the interface, polyamide 6 (PA6) at varying concentrations was introduced into the ABS/10 wt% SCF composite. The incorporation and increasing amount of PA6 in the composites increased tensile properties of the ABS/PA6/HCF systems due to the improved adhesion at the interface, which was confirmed by the ratio of tensile strength as an adhesion parameter. These results were also supported by scanning electron micrographs of the ABS/PA6/HCF composites, which exhibited an improved adhesion between the SCFs and the ABS/PA6 matrix. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation and properties of natural rubber composites reinforced with pretreated carbon nanotubes

In order to achieve dramatic improvements in the performance of rubber materials, the development of carbon nanotube (CNT)‐reinforced rubber composites was attempted. The CNT/natural rubber (NR) nanocomposite was prepared through solvent mixing on the basis of pretreatment of CNTs. Thermal properties, vulcanization characteristics, and physical and mechanical properties of the CNT/NR nanocomposites were characterized in contrast to the carbon black (CB)/NR composite. Through the addition of the CNTs treated using acid bath followed by ball milling with HRH (hydrated silica, resorcinol, and hexamethylene tetramine) bonding systems, the crystallization melting peak in differential scanning calorimetry (DSC) curves of NR weakened and the curing rate of NR slightly decreased. Meanwhile, the over‐curing reversion of CNT/NR nanocomposites was alleviated. The dispersion of the treated CNTs in the rubber matrix and interfacial bonding between them were rather good. The mechanical properties of the CNT‐reinforced NR showed a considerable increase compared to the neat NR and traditional CB/NR composite. At the same time, the CNT/NR nanocomposites exhibited better rebound resilience and dynamic compression properties. The storage modulus of the CNT/NR nanocomposites greatly exceeds that of neat NR and CB/NR composites under all temperature regions. The thermal stability of NR was also obviously improved with the addition of the treated CNTs. Copyright © 2008 John Wiley & Sons, Ltd.     

Polymer‐Infiltrated Aligned Carbon Nanotube Fibers by in situ Polymerization

Carbon nanotube–polymer composite fibers are obtained by infiltration of a monomer liquid into aligned carbon nanotube aerogel fibers with subsequent in situ polymerization. The monomer, methyl methacrylate (MMA), was infiltrated into the aerogel fibers of multi‐walled carbon nanotubes (MWNTs) at room temperature and subsequently polymerized at 50 °C into poly(methyl methacrylate) (PMMA). Cross‐sections of the PMMA/MWNT composite fibers showed that the PMMA filled the spaces of the nanotube fibers and bound the nanotubes together. PMMA in the composite fibers exhibited local order. The resultant composite fibers with 15 wt.‐% nanotube loading exhibited a 16‐fold and a 49‐fold increase in tensile strength and Young's modulus, respectively, compared to the control PMMA.