超声浸润法制备聚酰胺导电纤维及其性能研究

以聚酰胺纤维为基体,通过对纤维进行超声浸润的导电处理方法得到了含碳纳米管的聚酰胺导电长丝。该方法使碳纳米管部分插入纤维中以使其牢固地附着在纤维表面,改善了导电纤维涂层易脱落的缺点。通过扫描电子显微镜观察,导电性能、力学性能、耐水洗性能测试,探讨了分散混合液中甲酸体积分数、碳纳米管质量浓度对纤维导电性能的影响。结果显示:当分散混合液中甲酸体积分数为65%,碳纳米管质量浓度为3 g/L时,得到的碳纳米管/聚酰胺导电纤维的电导率可以达到2.33 S/m;甲酸的处理并未对纤维造成过大损伤,纤维力学性能良好;在经过60 min超声水洗后,纤维电导率只下降了一个数量级,耐水洗性能良好,且具有良好的力学性能。     

碳纳米管/聚丙烯腈导电纤维的结构与性能

使用浓硫酸和浓硝酸的混合溶液将多壁碳纳米管进行功能化处理后与聚丙烯腈(PAN)进行共混,采用湿法成形技术制备出了多壁碳纳米管/PAN导电纤维。采用扫描电镜、动态力学分析等手段对纤维的结构进行了分析,对纤维的物理机械性能及导电性能进行了测试。结果表明:添加碳纳米管5%时PAN纤维的强度、储存模量及玻璃化转变温度提高,断裂伸长率下降;添加经过功能化处理的碳纳米管可以有效地提高纤维的导电性能,当含量为5%时,电导率可达10-3S/cm。     

MWCNTs/PU导电纤维的制备与性能

通过将多壁碳纳米管(MWCNTs)与聚氨酯(PU)在N,N-二甲基乙酰胺(DMAc)溶液中共混,获得了MWCNTs/PU纺丝原液,采用模拟干法纺丝技术,制备了MWCNTs/PU导电纤维;并对纤维的导电性能进行了表征,研究了复合纤维在不同温度、不同拉伸条件下电导率的变化规律。结果表明:当温度从25℃升高至150℃时,纤维的电导率从2.5×10~(-2) S/m上升到3.0 S/m;当对纤维进行拉伸,伸长率从0增加至100%时,电导率从2.5×10~(-2) S/m下降到3.6×10~(-4) S/m;当固定伸长率25%,对纤维进行循环拉伸时,电导率在(4.0～6.0)×10~(-3) S/m之间上下起伏。     

石墨烯/碳纳米管涂层导电氨纶的制备及其性能研究

以44 dtex氨纶为原料,采用氧化石墨烯(GO)和壳聚糖(CS)分散的多壁碳纳米管(MWCNTs)基于静电层层自组装的方法,在氨纶表面进行交替涂覆处理,然后采用水合肼还原GO,制备了导电氨纶;研究了涂覆次数对氨纶导电性能的影响。结果表明:当CS与MWCNTs的质量比为15:1时,MWCNTs的分散效果最好,采用水合肼作为还原剂可将GO还原为石墨烯;采用GO和CS/MWCNTs分散液交替涂覆6次时,制备的导电氨纶具有良好的导电性能,其电阻可以从未涂覆时的10~7 MΩ/cm降低到0.18 MΩ/cm;导电氨纶具有优良的应力传感性能,其应变为10%时的应变系数为110,且经过1 000次循环拉伸后仍具有稳定的电信号响应;此外,导电氨纶还具有良好的耐水洗性能,且导电涂层不影响氨纶的热稳定性。     

多壁碳纳米管薄膜增强聚间二甲苯己二酰胺复合材料

多壁碳纳米管薄膜（BP）可以提升材料的力学性能和导热、导电性能，在制备热塑性复合材料方面具有巨大的应用潜力。采用先溶液浸渍后热压成型的方法制备了聚间二甲苯己二酰胺（MXD6）/BP复合材料，研究了BP含量对复合材料热导率、电导率、拉伸强度的影响。利用傅里叶变换红外光谱（FTIR）证实了碳纳米管和MXD6之间存在的π-π共轭效应，并用扫描电子显微镜（SEM）观察了MXD6在碳纳米管周围的分布。使用差示扫描量热（DSC）法和热重（TG）分析表征了复合材料的结晶性能和热稳定性，使用热导率仪、万用表和微机控制电子万能试验机测试了复合材料的导热性能、导电性能和力学性能。研究表明，在加入了碳纳米管后，MXD6的热导率、电导率和拉伸强度有了显著的提升。当复合材料中MXD6的质量分数为94.84%时，复合材料的拉伸强度达到了540.3 MPa，提高了6倍，并且复合材料的电导率达到24.814 S/cm，热导率为1.453 W/(m·K)，有效地拓展了MXD6的应用范围。     

纳米银颗粒-聚氨酯导电纤维的制备及拉伸传感应用

为了提高导电纤维的可拉伸性，采用湿法纺丝法制备聚氨酯纤维(TPU纤维)，将TPU纤维浸渍三氟乙酸银溶液并还原制备纤维状纳米银颗粒/聚氨酯导电纤维(AgNPs-TPU导电纤维)。探究了不同制备条件下AgNPs-TPU导电纤维的导电性和拉伸性，研究了AgNPs-TPU导电纤维拉伸传感性能。结果表明，以质量分数25%的TPU纺丝液所制备的TPU纤维浸渍20 mg/mL三氟乙酸银溶液还原4次后，AgNPs-TPU导电纤维单位长度电阻为10.79Ω，抗拉伸强度为5.14 MPa，断裂伸长率为576.18%。在不同拉伸应变的情况下，AgNPs-TPU导电纤维可通过自身电阻变化率的变化对不同的拉伸应变信息进行表征，实现将拉伸应变信号稳定转化为电信号，具备良好的拉伸传感性能。     

聚酯/多壁碳纳米管复合导电纤维的制备及性能

以羧基化多壁碳纳米管(MWNT-COOH)为导电填料,采用双螺杆熔融挤出制备聚酯(PET)/MWNT-COOH共混切片,通过熔融纺丝得到PET/MWNT-COOH复合纤维。研究了MWNT-COOH含量和拉伸处理对复合纤维可纺性、导电性能、力学性能和表面形貌等的影响。结果表明:当MWNT-COOH质量分数小于1.0%时,切片具有较好的可纺性,初生纤维的导电逾渗阈值为0.5%~1.0%;MWNT-COOH的加入提高了纤维的断裂强度,当MWNT-COOH质量分数为0.1%时,纤维断裂强度提高约34%,随着MWNT-COOH含量增加,纤维断裂强度的增加幅度逐渐下降;拉伸会使MWNT-COOH沿纤维轴向取向,有利于MWNTCOOH间的互相搭接形成导电通路,提高纤维的导电性能。     

基于SCFNA法辊压制备PDMS/SCF导电复合材料

利用空间限域强制组装法(SCFNA)的辊压成型方法制备了PDMS/SCF导电复合材料,并且,与传统平板热压印方式制备的PDMS/SCF导电复合材料的微观形貌、导电性能和拉伸力学性能进行对比分析。结果表明,采用SCFNA辊压方式制备的PDMS/SCF导电复合材料可以使碳纤维在聚合物基体内形成密实的导电网络,实现了强制组装;并且,由于辊子反复辊压混料,聚合物基体中的碳纤维发生了取向,因此,在碳纤维含量相同的情况下,与平板热压印法相比,辊压方法制备的PDMS/SCF导电复合材料具有更好的电学性能和拉伸力学性能;在碳纤维质量分数为6%的情况下,复合材料的电导率最大提高了105.1%,拉伸强度提高了18.6%,断裂伸长率提高了9.16%。     

乙二胺修饰的碳纳米管对环氧树脂力学性能的影响

利用乙二胺对多壁碳纳米管(MWNTs)进行化学修饰,并制备碳纳米管/环氧树脂复合材料,研究了乙二胺修饰的碳纳米管对碳纳米管/环氧树脂复合材料力学性能的影响。实验表明,碳纳米管经乙二胺修饰后,改善了它在环氧树脂中的分散性,提高了环氧树脂复合材料的力学性能。氨基化碳纳米管用量达1.0%时,复合材料的冲击强度、断裂伸长率、拉伸强度和弯曲强度分别较纯环氧树脂提高200%、275%、48%和30%。     

水性聚氨酯/十二烷基苯磺酸钠修饰多壁碳纳米管复合材料的制备与表征

以十二烷基苯磺酸钠(SDBS)修饰多壁碳纳米管(MWNTs)得到MWNTs-SDBS,采用溶液共混法,制备出水性聚氨酯/SDBS修饰多壁碳纳米管复合材料。探讨了MWNTs-SDBS含量对复合材料力学性能、热性能和电性能的影响及复合材料的微观结构。结果表明:碳纳米管在水性聚氨酯中分散均匀,明显提高了水性聚氨酯的力学性能和导电性。与纯水性聚氨酯相比,当MWNTs-SDBS含量为0.3%时,复合材料的拉伸强度和断裂伸长率分别提高9%和29%;当其含量为0.9%时,复合材料的电阻率提高接近9个数量级。此外,添加碳纳米管降低了聚氨酯软段的结晶性能。     

High‐performance electromagnetic interference shielding material based on an effective mixing protocol

A facile and economic method is developed for the fabrication of new lightweight materials with high electromagnetic interference (EMI) shielding performance, good mechanical properties and low electrical percolation threshold through melt mixing. Electrical properties, DC conductivity, EMI shielding performance and mechanical properties of poly(trimethylene terephthalate) (PTT)/multiwalled carbon nanotube (MWCNT) nanocomposites with varying filler loading of MWCNTs were investigated. High‐resolution transmission electron microscopy was used to determine the distribution of MWCNTs in the PTT matrix. The newly developed nanocomposites show excellent dielectric and EMI shielding properties. Theoretical electrical percolation threshold was achieved at 0.21 wt% loading of MWCNTs, due to the high aspect ratio and the three‐dimensional network formation of MWCNTs. Experimental DC conductivity values were compared with those of theoretical models such as the Voet, Bueche and Scarisbrick models, which showed good agreement. The PTT/3% MWCNT composite showed an EMI shielding value of ～38 dB (99.99% attenuation) with a sample thickness of 2 mm. Power balance was used to determine the actual contribution of reflection, absorption and transmission loss to the total EMI shielding value. The nanocomposites showed good tensile and impact properties and the composite with 2% MWCNTs exhibited an improvement in tensile strength of as much as 96%. © 2018 Society of Chemical Industry     

Facile fabrication of PVA composite fibers with high fraction of multiwalled carbon nanotubes by gel spinning

Poly(vinyl alcohol) (PVA) composite fibers with high fraction of multiwalled carbon nanotubes (MWCNTs) were prepared by gel spinning process. Here, a modified process was introduced to prepare concentrated PVA/MWCNTs/DMSO spinning dope, and to attain good dispersion of MWCNTs in the fibers. The final composite fibers were studied by thermogravimetric analyzer (TGA), Fourier transform infrared spectrometer (FTIR), Raman spectroscopy, differential scanning calorimetry (DSC), and WAXD analysis. The total content of MWCNTs in PVA composite fibers, from 5 to 30 wt%, was confirmed by TGA analysis. FTIR and Raman measurements demonstrated the existence of strong hydrogen interaction between MWCNTs and PVA matrix. SEM images of composite fibers showed smooth surface, regular cross‐section shape and good dispersion of MWCNTs in the fibers. DSC analysis showed that the crystallinity first increased and then decreased with the increase of MWCNTs contents. It can be concluded that low concentration of MWNCTs can act as nucleation sites for crystallization of PVA component, and large amount of MWCNTs may impede the crystallization of PVA component. The WAXD analysis results indicated that the crystal orientation of the PVA component in PVA composite fibers is almost identical at the same drawn ratio. Polarized Raman analysis indicated a small increase in MWCNTs orientation for the composite fibers. The mechanical properties tests showed that the composite fibers exhibit significant improvement in tensile strength and modulus as compared to the neat PVA fibers. The composite fibers also showed sustained growth in electrical conductivity. POLYM. ENG. SCI., 58:37–45, 2018. © 2017 Society of Plastics Engineers     

Investigation of electrical,mechanical, and thermal properties of functionalized multiwalled carbon nanotubes‐reduced graphene Oxide/PMMA hybrid nanocomposites

Electrical, mechanical, and thermal properties of the poly(methyl methacrylate) (PMMA) composites containing functionalized multiwalled carbon nanotubes (f‐MWCNTs) and reduced graphene oxide (rGO) hybrid nanofillers have been investigated. The observed electrical percolation threshold of FHC is 0.8 wt% with maximum conductivity of 1.21 × 10^?3 S/cm at 4 wt% of f‐MWCNTs. The electrical transport mechanism and magneto resistance studied of hybrid composites have also been investigated. Progressive addition of f‐MWCNTs in rGO/PMMA composite results increase in mechanical (tensile strength and Young's modulus) and thermal (thermal stability) properties of f‐MWCNTs‐rGO/PMMA hybrid nanocomposites (FHC). The increased mechanical properties are due to the efficient load transfer from PMMA matrix to f‐MWCNTs and rGO through better chemical interaction. The strong interaction between PMMA and f‐MWCNTs‐rGO in FHC is the main cause for improved thermal stability. POLYM. ENG. SCI., 59:1075–1083, 2019. © 2019 Society of Plastics Engineers     

Preparation and properties of polyurethane/multiwalled carbon nanotube nanocomposites by a spray drying process

A spray drying approach has been used to prepare polyurethane/multiwalled carbon nanotube (PU/MWCNT) composites. By using this method, the MWCNTs can be dispersed homogeneously in the PU matrix in an attempt to improve the mechanical properties of the nanocomposites. The morphology of the resulting PU/MWCNT composites was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM observations illustrate that the MWCNTs are dispersed finely and uniformly in the PU matrix. X‐ray diffraction results indicate that the microphase separation structure of the PU is slightly affected by the presence of the MWCNTs. The mechanical properties such as tensile strength, tensile modulus, elongation at break, and hardness of the nanocomposites were studied. The electrical and the thermal conductivity of the nanocomposites were also evaluated. The results show that both the electrical and the thermal conductivity increase with the increase of MWCNT loading. In addition, the percolation threshold value of the PU composites is significantly reduced to about 5 wt % because of the high aspect ratio of carbon nanotubes and exclusive effect of latex particles of PU emulsion in dispersion. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Polylactide/graphite nanosheets/MWCNTs nanocomposites with enhanced mechanical, thermal and electrical properties

In this study, we have prepared a series of novel biodegradable polymer [polylactide (PLA)]-based nanocomposites using graphite nanosheets (GNs) and multi-walled carbon nanotubes (MWCNTs) by solution-blending technique and investigated their morphologies, structures, thermal stabilities, mechanical and dielectric properties, and electrical and thermal conductivities. Before preparation of the PLA/GNs/MWCNTs nanocomposites, the raw GNs used were endured a rapid expansion by thermal treatment. Temperature of this treatment had some obvious impacts on morphological changes of graphite nanosheets which were verified by means of scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques. Resultant nanocomposites were characterized and evaluated by means of SEM, XRD, thermal conductivity measurements, tensile and impact tests, thermogravimetric analysis and dielectric measurements. Results obtained in this study indicated that thermal-expanded GNs in the presence of MWCNTs facilitate the formation of an appropriate conductive network in PLA matrix which resulted in a relatively low percolation threshold for thermal and electrical conductions of PLA/GNs/MWCNTs nanocomposites. Significant improvements in thermal and electrical conductivities, thermal stability and mechanical properties of PLA/GNs/MWCNTs nanocomposites obtained through the presence of both nanoparticles in PLA matrix were associated with their good co-dispersion and co-reinforcement effects. The macroscopic properties of nanocomposites were found to be strongly dependent on their components, concentrations, dispersion, and the resulted morphological structures.     

Synergetic effects of graphene platelets and carbon nanotubes on the mechanical and thermal properties of epoxy composites

A remarkable synergetic effect between the multi-graphene platelets (MGPs) and multi-walled carbon nanotubes (MWCNTs) in improving the mechanical properties and thermal conductivity of epoxy composites is demonstrated. Stacking of individual two-dimensional MGPs is effectively inhibited by introducing one-dimensional MWCNTs. Long and tortuous MWCNTs can bridge adjacent MGPs and inhibit their aggregation, resulting in a high contact area between the MGP/MWCNT structures and the polymer matrix. Scanning electron microscope images of the fracture surfaces of the epoxy matrix showed that MWCNT/MGP hybrid nanofillers exhibited higher solubility and better compatibility than individual MWCNTs and MGPs did. The tensile strength of GD400-MWCNT/MGP/epoxy composites was 35.4% higher than that of the epoxy alone, compared to only a 0.9% increase in tensile strength for MGP/epoxy composites over the epoxy compound. Thermal conductivity increased by 146.9% using GD400-MWCNT/MGP hybrid fillers and 23.9% for MGP fillers, compared to non-derivatised epoxy.     

Fabrication and Characterization of Highly Oriented Composite Nanofibers with Excellent Mechanical Strength and Thermal Stability

Here, highly‐oriented poly(m‐phenylene isophthalamide)/polyacrylonitrile multi‐walled carbon nanotube (PMIA/PAN‐MWCNT) composite nanofiber membranes with excellent mechanical strength and thermal stability are successfully produced using electrospinning. It is demonstrated that the cooperation of multi‐walled carbon nanotubes (MWCNT) and high‐speed rotating collection is beneficial to the acquisition of highly oriented fibers and effectively improves the mechanical strength of the membrane along the orientation direction. Specifically, the tensile stress of poly(m‐phenylene isophthalamide)/polyacrylonitrile (PMIA/PAN) membrane is enhanced significantly from 10.6 to 20.7 MPa, benefiting from the highly oriented alignment of the fibers as well as the reinforcing effect of MWCNTs on the fibers. Furthermore, the stressing process of single fiber and fiber aggregates is carefully simulated, and the influence of MWCNTs on the mechanical properties of PMIA/PAN‐MWCNT membranes is analyzed comprehensively, providing a meaningful auxiliary means for the study of mechanical properties. In addition, the composite nanofiber membrane has the advantages of both PMIA and PAN, possessing high temperature resistance, flame‐retardancy, and chemical stability, for an ideal high‐temperature material. In short, the as‐prepared PMIA/PAN‐MWCNT composite membrane with excellent comprehensive property emerges a promising application in many fields, especially in high‐tech.     

强剪切流动下聚丙烯基复合材料介电性能和结构演变的研究

研究了多壁碳纳米管(MWCNT)、线型低密度聚乙烯(LLDPE)和强剪切流动场对聚丙烯(PP)/MWCNT/LLDPE复合材料的导电性能、结晶性能、力学性能和介电性能的研究。结果表明,PP/MWCNT复合材料随着MWCNT含量的提高,导电性能逐步改善,导电逾渗值约为1.8%,而第二分散相LLDPE的引入使复合材料的导电性能表现出了先降低后升高的现象,并且随着LLDPE含量的增加,MWCNT逐步向LLDPE内部迁移,构成了双连续结构。复合材料经过固态口模拉伸的强剪切流动场之后,随着拉伸速率从10 mm/min增加到300 mm/min的过程中,复合材料的融化温度逐渐向高温方向偏移,表现出了片层厚度增加的现象。复合材料内部分子链取向和纤维结构的形成,能够显著提高复合材料的拉伸强度和介电性能,拉伸强度提高从约50 MPa提高到了约240 MPa,提高了约380%。MWCNT和强剪切流动场的引入也使复合材料的介电常数大幅提升。     

Toward improved mechanical performance of multiscale carbon fiber and carbon nanotube epoxy composites

A novel class of multiscale epoxy composites was developed containing carbon fibers (CFs) and multiwalled carbon nanotubes (MWCNTs) to explore their mutual effect on the mechanical performance of composites. The loading of CFs in composites was kept constant at ∼60 wt%, while the contents of MWCNTs were increased from 0.5 to 2.0 wt%. MWCNTs were functionalized through acid treatment before incorporating into epoxy matrix to promote dispersion quality. The developed composites were characterized microstructurally by scanning electron microscopy and mechanically by tensile, flexural, edgewise compression, and hardness tests. Homogeneous dispersion of MWCNTs was observed until their loading of 1.5 wt%, which enhanced the mechanical performance of composites. Hardness increased up to 47% while tensile, flexural, and edgewise compressive moduli increased to 40%, 16.3%, and 164%, respectively. Moreover, tensile, flexural, and edgewise compressive strengths showed rises of 45%, 15.2%, and 43%, respectively. The fracture strain increased in both the tensile and flexural tests while it decreased in edgewise compressive tests. Increasing the MWCNTs in composites to 2.0 wt% produced their agglomerates and reversed the rising trend in mechanical properties. POLYM. COMPOS., 38:1519–1528, 2017. © 2015 Society of Plastics Engineers     

MWCNTs含量对纤维素/[BMIM]Cl溶液及其纤维性能和形态结构的影响

分析了经表面功能化的MWCNTs(多壁碳纳米管)在纤维素/[BMIM]Cl(1-丁基-3-甲基咪唑氯盐)体系中的分散稳定性,探讨了MWCNTs/纤维素/[BMIM]Cl溶液的流变行为,并通过干湿法制备了不同MWCNTs含量的离子液体法纤维素纤维,对其力学性能和表面形态结构进行了研究。结果表明:MWCNTs/纤维素/[BMIM]Cl溶液为切力变稀流体。随着溶液中MWCNTs添加量的增加,溶液表观黏度先增大后减小;适量的MWCNTs可以均匀分散在纤维素/[BMIM]Cl溶液体系中并具有良好的可纺性,所制得的MWCNTs/纤维素纤维表面较光滑且力学性能明显改善。其中,含1%MWCNTs的纤维素纤维的初始模量和断裂强度较高,分别比未添加MWCNTs的纤维提高66.7%和22.7%。