Crystallization Behavior and Mechanical Properties of Poly(vinylidene fluoride)/multi-walled Carbon Nanotube Nanocomposites

Poly（vinylidene fluoride）（PVDF）/multi-walled carbon nanotube（MWCNT） nanocomposites were prepared by means of ultrasonic dispersion method. X-ray diffraction（XRD） results indicate that incorporating MWCNTs into PVDF caused the formation of β phase. A thermal annealing at 130 ℃ confirmed that the β phase was stable in the nanocomposites. Differential scanning calorimetry（DSC） results indicate that the melting temperature slightly increased while the heat of fusion markedly decreased with increasing MWCNT content. The tensile strength and modulus of PVDF were improved by loading the MWCNTs. The scanning electron microscopy（SEM） observations showed that MWCNTs were uniformly dispersed in the PVDF matrix and an interfacial adhesion between MWCNT and PVDF was achieved, which was responsible for the enhancement in the tensile strength and modulus of PVDE.

Synthesis and Characterization of Aluminum/Carbon Nanotubes Composites： Study of Interfacial Interaction

Abstract： In this work, the authors present a study of growth and characterization of composite based on AI and CNT （carbon nanotubes. The composites were prepared by a chemical mixing method and characterized by SEM analysis, energy dispersed X-ray measurements, X-ray photoelectron spectroscopy and cathodoluminescence spectroscopy. The analysis showed that the composites are formed by macro-cluster of aluminum oxide on a network of CNT without formation of chemical bonds at interface between particles. The results are compared with those obtained for a sample of CNT with AI traces （〈 0.5%）. They show that only the presence of metal traces changes the nanotubes optical properties, with a luminescence signal centered at about 380 nm. These luminescence signals are caused by the adhesion between CNT and AI micro-clusters that promote the formation of band gap with some local energy levels.

Multifunctional characteristics of 3D printed polymer nanocomposites under monotonic and cyclic compression

This study presents the multifunctional characteristics of multi-walled carbon nanotube(MWCNT)/polypropylene random copolymer(PPR) composites enabled via fused filament fabrication(FFF) under monotonic and quasi-static cyclic compression. Utilizing in-house MWCNT-engineered PPR filament feedstocks, both bulk and cellular composites were realized. The morphological features of nanocomposites were examined via scanning electron microscopy, which reveals that MWCNTs are uniformly dispersed. The uniformly dispersed MWCNTs forms an electrically conductive network within the PPR matrix, and the resulting nanocomposite shows good electrical conductivity(~10^(-1)S/cm), improved mechanical performance(modulus increases by 125% and compressive strength increases by 25% for 8 wt% MWCNT loading) and pronounced piezoresistive response(gauge factor of 27.9-8.5 for bulk samples)under compression. The influence of strain rate on the piezoresistive response of bulk samples(4 wt% of MWCNT) under compression was also measured. Under repeated cyclic compression(2% constant strain amplitude), the nanocomposite exhibited stable piezoresistive performance up to 100 cycles. The piezoresistive response under repeated cyclic loading with increasing strain amplitude of was also assessed.The gauge factor of BCC and FCC cellular composites(4 wt% of MWCNT) with a relative density of 30%was observed to be 46.4 and 30.2 respectively, under compression. The higher sensitivity of the BCC plate-lattice could be attributed to its higher degree of stretching-dominated deformation behavior than the FCC plate-lattice, which exhibits bending-dominated behavior. The 3D printed cellular PPR/MWCNT composites structures were found to show excellent piezoresistive self-sensing characteristics and open new avenues for in situ structural health monitoring in various applications.

3D vertically aligned microchannel structure to enhance piezoelectric energy harvesting performance of PZT/PVDF&CNTs piezoelectric composites

Piezoelectric energy harvesters(PEHs)have attracted significant attention with the ability of converting mechanical energy into electrical energy and power the self-powered microelectronic components.Generally,material's superior energy harvesting performance is closely related to its high transduction coefficient(d_(33)×g_(33)),which is dependent on higher piezoelectric coefficient d33 and lower dielectric constantεr of materials.However,the high d33 and lowεr are difficult to be simultaneously achieved in piezoelectric ceramics.Herein,lead zirconate titanate(PZT)based piezoelectric composites with vertically aligned microchannel structure are constructed by phase-inversion method.The polyvinylidene fluoride(PVDF)and carbon nanotubes(CNTs)are mixed as fillers to fabricate PZT/PVDF&CNTs composites.The unique structure and uniformly distributed CNTs network enhance the polarization and thus improve the d33.The PVDF filler effectively reduce theεr.As a consequence,the excellent piezoelectric coefficient(d_(33)=595 pC/N)and relatively low dielectric constant(ε_(r)=1,603)were obtained in PZT/PVDF&CNTs composites,which generated an ultra-high d_(33)×g_(33) of 24,942×10^(−15) m^(2)/N.Therefore,the PZT/PVDF&CNTs piezoelectric composites achieve excellent energy harvesting performance(output voltage:66 V,short current:39.22μA,and power density:1.25μW/mm^(2)).Our strategy effectively boosts the performance of piezoelectric-polymer composites,which has certain guiding significance for design of energy harvesters.

Preparation of well-aligned carbon nanotubes/silicon nanowires core-sheath composite structure arrays in porous anodic aluminum oxide templates

The well-aligned carbon nanotubes (CNTs) arrays with opened ends were prepared in ordered pores of anodic aluminum oxide (AAO) template by the chemical vapor deposition (CVD) method. After then, silicon nanowires (SiNWs) were deposited in the hollow cavities of CNTs. By using this method, CNTs/SiNWs core-sheath composite structure arrays were synthesized successfully. Growing structures and physical properties of the CNTs/SiNWs composite structure arrays were analyzed and researched by the scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction spectrum (XRD), respectively. The field emission (FE) behavior of the CNTs/SiNWs composite structure arrays was studied based on Fowler-Nordheim tunneling mechanism and current-voltage (I-V) curve. And the photoluminescence (PL) was also characterized. Significantly, the CNTs/SiNWs core-sheath composite structure nanowire fabricated by AAO template method is characteristic of a metal/semiconductor (M/S) behavior and can be utilized to synthesize nanoscale PN junction or Schottky diode device. This process also could be useful for the fabrication of SiNWs and other nanoscale core-sheath composite structure nanowires with chemically inert interfaces for nanoscale electronic and device applications where surface oxidation is undesirable. The diameters and lengths of nanoscale composite structure arrays can be dominated easily, and the experimental result shows that the curling and twisting structures are fewer than those prepared by other synthesized methods.

Study of Electroless Ni-P-CNTs Composite Plating

The electroless Ni-P-carbon nanotubes composite plating was studied on the copper substrate. Metallurgical microscope, scanning electronic microscope, X-ray diffractometer and micro hardness tester were used to study the structure, constitution and performance of the electroless Ni-P-carbon nanotubes composite deposit. Experiential results show that, with the increment of carbon nanotubes content in electroless plating solution, the grain size on the sample surface decreases whereas the density of grains and the hardness for composite deposit increases. Moreover, adding carbon nanotubes not only improves the degree of crystallization for the composite deposit but also helps their transformation from the amorphous state to the nanocrystal state.

A novel approach for fabricating a CNT/AlSi composite with the self-aligned nacre-like architecture by cold spraying

A fully dense carbon nanotubes (CNTs) reinforced AlSi matrix composite with the multiscale nacre-like architecture was designed and successfully realized by flake powder metallurgy followed by cold spraying (CS). The nanolaminated and ultrafine-grained structure initially created in the CNT/AlSi flaky powder was perfectly conserved, due to the typical ‘cold’ feature of CS. As discussed based on finite element analysis and single splat observation, self-alignment behavior of the flaky powders during impact also allowed the formation of the microlaminated structure. Hence, the scalable CS technique opens a new avenue for bioinspired material design and fabrication with complex shape.

Fe_(2)O_(3)-MWNTs Composite with Reinforced Concrete Structure as High-performance Anode Material for Lithium-ion Batteries

A Fe_(2)O_(3)-MWNTs(multi-walled carbon nanotubes)composite with a reinforced concrete structure was fabricated employing a two-step method which involves a sol-gel process followed by high-temperature in situ sintering.This Fe_(2)O_(3)-MWNTs composite,intended to be used as an anode material for lithium-ion batteries,maintained a reversible capacity as high as 896.3 mA·h/g after 100 cycles at a current density of 100 mA/g and the initial coulombic efficiency reached 75.5%.The rate capabilities of the Fe_(2)O_(3)-MWNTs composite,evaluated using the ratios of capacity at 100,200,500,1000,2000 and 100 mA/g after every 10 cycles,were determined to be 904.7,852.1,759.0,653.8,566.8 and 866.3 mA·h/g,respectively.Such a superior electrochemical performance of the Fe_(2)O_(3)-MWNTs composite is mainly attributed to the reinforced concrete construction,in which the MWNTs function as the skeleton and conductive network.Such a structure contributes to shortening the transport pathways for both Li+and electrons,enhancing conductivity and accommodating volume expansion during prolonged cycling.This Fe_(2)O_(3)-MWNTs composite with the designed structure is a promising anode material for high-performance lithium-ion batteries.

CNTs杂化粒子改性PP/PGA复合材料的结构与性能

为解决聚丙烯/聚乙醇酸(PP/PGA)共混物由于相容性较差导致力学性能存在局限性的问题,采用过硫酸铵-胺氧化还原引发体系,通过表面引发接枝聚合法(SIP)制备了碳纳米管接枝聚甲基丙烯酸缩水甘油酯杂化粒子(CNTs@PGMA),以CNTs@PGMA杂化粒子和聚丙烯接枝马来酸酐(PP-g-MAH)为协同增容体系,通过熔融共混法制备了PP/PGA/CNTs复合材料,采用傅里叶变换红外光谱仪和透射电子显微镜对CNTs@PGMA进行了表征,结果表明PGMA通过SIP成功接枝在CNTs表面。采用拉伸测试、差示扫描量热仪、热重分析、旋转流变和降解试验等方法研究了CNTs@PGMA用量对复合材料力学性能、热性能、降解性能和流变行为的影响。结果表明,在PP/PGA/PP-g-MAH体系中加入CNTs@PGMA后其相容性得到提升,随杂化粒子用量增加,复合材料拉伸强度先增大后减小,热稳定性得到提升,PGA结晶逐渐受限甚至无熔融峰出现。杂化粒子的加入形成了三维网络结构,提高了复合材料熔体弹性,熔体表现出更强的非牛顿性和剪切变稀行为,同时PGA的降解过程受到抑制。当CNTs@PGMA用量为5份时,复合材料的拉伸强度最大为41.25 MPa,断裂伸长率为66.03%,PGA在42 d时的降解率下降至10%以内,拉伸强度维持率达到91%。

硅橡胶/多壁碳纳米管复合材料应变感知性能研究

通过开炼法制备出甲基乙烯基硅橡胶(VMQ)/多壁碳纳米管(MWCNT)复合材料,研究MWCNT含量对复合材料分散性能、导电性能及电阻-应变响应性能的影响。结果表明:适量的MWCNT能够均匀分散在VMQ中,形成三维隧穿导电网络,使复合材料具备较低的渗流阈值(2.51%,质量分数,下同),较大的传感范围(>200%)及高灵敏度(GF>2 546.16),在多次循环过程中具有稳定的电阻响应信号,特别是在4 000次循环中展现出优异的电阻信号稳定性,同时没有出现肩峰现象。通过隧道效应理论模型分析,解释了电阻-应变响应机理,明确复合材料具有对大变形隔震支座进行实时应变监测的潜力。

双氢氧化物/官能化碳纳米管复合协效阻燃剂设计及应用

环氧树脂(EPs)广泛应用于飞机结构部件中,为其开发高性能阻燃剂对提高飞机防火安全性具有重要现实意义。本研究通过一锅法在交织的官能化碳纳米管(F-CNTs)骨架上生长镁铝双金属氢氧化物(MgAl-LDH)纳米片,构建得到二者的复合结构MgAl-LDH/F-CNTs。以MgAl-LDH/F-CNTs复合结构作为力学支撑,进一步负载CuMoO4纳米颗粒,最终得到适用于环氧树脂的MgAl-LDH/F-CNTs-CuMoO4协效阻燃剂。其中,MgAl-LDH/F-CNTs复合结构可助于实现各阻燃组分在环氧树脂聚合物基材中的均匀分散,相较于未经阻燃处理的环氧树脂材料,阻燃环氧树脂在燃烧测试中其峰值热释放速率可降低40.5%,总热释放量可降低7.49%,CO生成量和总烟气释放量可显著降低43.0%和26.3%,极限氧指数LOI提升38.2%,可见经阻燃处理后的EP复合材料阻燃性能显著提升。此外,经阻燃处理后环氧树脂拉伸、弯曲强度仅下降7.1%和22.4%,表明CNTs的添加以及MgAl-LDH/F-CNTs复合结构的构建能够有效补偿LDH添加对EP力学性能的影响。

磷酸铁锂电池碳纳米管膜加热结构设计及验证

针对磷酸铁锂电池低温环境下的性能衰减问题,设计开发了一种轻质高强、低压安全、高效节能的磷酸铁锂电池抗低温纤维碳纳米管膜加热功能结构并开展了实验验证。采用热压工艺实现了碳纳米管薄膜与复合材料层合结构的一体化成形。实验验证了FCL(fiber carbon-nanotube film laminated composite)加热器良好的温度均匀性、稳定性以及抗热疲劳性能。开展了低温环境下磷酸铁锂电池加热实验,并与传统的PTC(positive temperature coefficient)加热器进行了对比分析,结果表明:相较于传统的PTC加热器,FCL加热器质量减轻了59%,能量消耗降低了3.5%,温升效率提高了26%,功率质量比提升了195%。

SiO_(2)/聚乙二醇200/碳纳米管剪切增稠液浸渍芳纶织物及其复合材料防刺性能

为优化高性能织物的防刺性能,采用SiO 2和不同长径比的多壁碳纳米管(MWCNTs)制备多相剪切增稠液(MSTFs),研究MWCNTs的长径比与添加量对剪切增稠液流变性能的影响及MSTFs芳纶复合织物的防刺性能。之后将MSTFs复合织物与碳化硅/聚氨酯(SiC/TPU)涂层织物叠层制备双层防刺复合材料,探究叠层顺序对层合复合材料抗穿刺性能的影响。结果得出:长径比较大的碳纳米管对提高剪切增稠液(STF)的增稠效果更优;随着碳纳米管含量的增加,剪切增稠效果逐渐增强。实验结果表明:MSTFs(0.4%MWCNTs-A)浸渍芳纶织物的最大穿刺载荷较纯STF浸渍芳纶织物提高154.33%;不同叠层结构中以剪切增稠液浸渍织物为面层、SiC/TPU涂层织物为背层的双层复合织物表现出更优的防刺性能。

Improving interface adhesion in TiNi wire/shape memory epoxy composites using carbon nanotubes

In order to increase both the interfacial strength and interphase region strength between TiNi wires and shape memory epoxy,a novel interface structure including aminated CNTs was designed.The morphology shows that after electroplating and etching,continuous and homogeneous concave-convex layers form on the surface of astreated TiNi wires,meanwhile aminated CNTs were planted on the surface which could react with shape memory epoxy at the interface region.The interfacial shear strength increases first with the CNT content rising but then a dramatic drop happens,and the maximum is obtained at CNT content of 0.6 g·L^(-1),which is about twice the result of acid etching TiNi wires.

Preparation and thermal properties of layered porous carbon nanotube/epoxy resin composite films

A floating-catalyst spray pyrolysis method was used to synthesize carbon nanotube(CNT)thin films.With the use of ammonium chloride as a pore-former and epoxy resin(EP)as an adhesive,CNT/EP composite films with a porous structure were prepared through the post-heat treatment.These films have excellent thermal insulation(0.029–0.048 W·m^−1·K^−1)at the thickness direction as well as a good thermal conductivity(40–60 Wm^−1·K^−1)in the film plane.This study provides a new film material for thermal control systems that demand a good thermal conductivity in the plane but outstanding thermal insulation at the thickness direction.

氧化石墨烯/碳纳米管对几种典型高分子材料的性能影响

氧化石墨烯/碳纳米管(GO/CNTs)作为理想的碳纳米材料,拥有独特三维空间结构和巨大的比表面积,被广泛应用于增强高分子材料,可提升复合材料物理力学性能、稳定性,并赋予复合材料优异的导热、导电、动态力学等性能。本文介绍了常用于制备GO/CNTs基的制备方法,重点对比了铸层/涂覆法、真空抽滤法、共混法制备复合材料的微观形貌与优缺点,探讨了结构控制与GO/CNTs基复合材料性能的关系,详细介绍了GO的改性、CNTs的改性和GO/CNTs的掺杂与高分子材料的相容性,并对其在环氧树脂、橡胶、可生物降解聚合物的应用进行了分析,探究GO/CNTs对复合材料物理力学性能和功能性的影响,最后总结了GO/CNTs改性高分子材料的技术优势及目前存在的问题,展望未来发展方向,以期对GO/CNTs改性环氧树脂、橡胶等高分子材料制备高附加值产品提供参考。

Carbon nanotubes grown on glass fiber as a strain sensor for real time structural health monitoring

In order to more effectively monitor the health of composite structures,a fuzzy fiber sensor has been developed.The fuzzy fiber is a bundle of glass fibers with carbon nanotubes or nanofibers(CNTs or CNFs)grown on the surface.The nanotube coating makes the fiber bundle conductive while the small conductive path increases sensitivity.The fuzzy fiber sensor can replace conventional metal foil strain gauges in composite applications.The electrical response of the sensor is monitored in real time to measure strain,vibration,cracking and delamination.Continuous monitoring provides instant notification of any problems.Implementation of this sensor network in a composite can increase service life,decrease maintenance costs and greatly reduce inspection downtime.

有序介孔钴基Co@C@CNTs复合材料可控制备和表征

以钴作为金属节点,二甲基咪唑(2-MI)为有机配体,十六烷基三甲基溴化铵(CTAB)为表面活性剂,碳纳米管(CNTs)为模板,采用牺牲模板法制备了具有大孔径的钴基Co@C@CNTs复合材料。采用X-射线衍射、扫描电镜、N_(2)物理吸附以及热重等对其进行表征,考察CNTs加入量对钴基复合材料孔结构的影响。结果表明,CNTs的加入可以有序扩大Co@C的孔径和孔容。CNTs的最佳掺杂量为0.84 g,此时Co@C@CNTs的孔径(6.6 nm)和孔容(0.4250 cm^(3)/g)较大,均大于Co@C的孔径(2.9 nm)和孔容(0.2175 cm^(3)/g)。

聚苯乙烯/碳纳米管复合材料的力学性能与结构

研究了聚苯乙烯 /碳纳米管复合材料的力学性能 ,探讨了该材料的微观结构与性能之间的关系 .结果表明 ,在碳纳米管加入量为 1.0 %时 ,复合材料的拉伸强度和冲击韧性较高 ,综合性能达到最佳 .此时 ,碳纳米管在基体中呈纳米级分布 ,而且碳纳米管对苯乙烯的聚合过程没有阻碍作用 .

碳纳米管的力学性能及碳纳米管复合材料研究

对碳纳米管力学行为和碳纳米管复合材料的研究文献进行了综述.首先介绍了碳纳米管结构稳定性和力学性能的研究进展,包括理论模拟和实验的研究结果.结果表明,碳纳米管有着优异的力学性能,其在复合材料应用方面有着巨大的潜力.然后,系统地总结了碳纳米管在增强高分子材料、金属材料和陶瓷材料方面的应用,指出外场力传递效应是值得关注的课题.最后,对该领域工作做了一些讨论和展望.