碳纳米管改性CF/PEEK复合材料的力学与电磁屏蔽性能

为了制备兼具优异力学性能和电磁干扰屏蔽效能的结构功能一体化耐高温热塑性复合材料,对添加不同组分碳纳米管(CNT)的连续碳纤维增强聚醚醚酮复合材料(CF-CNT/PEEK)的力学性能、电导率以及电磁干扰屏蔽效能(EMI SE)进行了研究。考察用上浆后的CNT (SCNT)作为导电填料制备的SCF-SCNT/PEEK层合板力学性能、界面形貌和屏蔽效能,并与不进行表面修饰、仅活化的CNT (ACNT)的效果做对比实验。结果表明,适量的CNT会使CF/PEEK层合板的力学性能、电导率和EMI SE得到提高;SCNT比ACNT更容易在PEEK中均匀分散,且与SCF和PEEK的结合更好。所有样品中,仅添加1wt%SCNT的SCF-SCNT/PEEK层合板与不添加CNT的层合板相比,拉伸强度提高了20.8%,达到778 MPa;弯曲强度提高了25.9%,达到1 684 MPa;电导率提升5倍,达到0.15 S/cm;电磁干扰屏蔽效能提升69.76%,平均值达到34.97 dB。     

掺入碳纳米管提高聚苯乙炔的导电性研究

用AlCl3作催化剂制备了聚苯乙炔（PPA），采用共混法制备了碳纳米管（CNTs）与PPA的复合材料，并进行了导电性能测试，结果表明，当CNTs含量增加时，复合材料的电导率升高，CNTs含量为3%时是复合材料导电的临界浓度，当CNTs含量达25%时复合材料达极限电导率，比纯的PPA的电导率提高了13个数量级。CNTs/PPA复合材料的导电机理符合导电通道理论。     

导电硅橡胶泡沫材料的制备与性能研究

在硅橡胶基体中添加碳系导电填料(CB、CNT),利用超临界CO2发泡技术,制备了CB/硅橡胶、CNT/硅橡胶以及CB/CNT/硅橡胶复合导电泡沫材料,研究了混料胶料的流变行为以及发泡前后复合材料电导率、电磁屏蔽效能的变化规律。结果表明,CB与CNT均会阻碍硅橡胶复合材料的初始交联,导电填料含量越多交联越迟缓。CB/CNT/硅橡胶复配体系中更容易形成导电通路,当CB/CNT(1∶1)总含量为8%(质量分数)时,硅橡胶复合材料的电导率可达10^-5 S/cm,其电磁屏蔽效能(EI)为14~26 dB。发泡后,硅橡胶复合材料的电导率及EI值均有所下降。     

MWCNTs改善WS2/三元乙丙橡胶复合材料的非线性电导特性与热导性能

通过在一定量的纳米WS₂中添加极少量的多壁碳纳米管（MWCNTs）,形成MWCNTs-WS₂复配填料,采用双辊开炼机将三元乙丙橡胶（EPDM）与不同配比的复配填料混合制备了不同MWCNTs含量的MWCNTs-WS₂/EPDM复合材料。并研究了极少量的MWCNTs添加对MWCNTs-WS₂/EPDM复合材料非线性电导性能、直流击穿性能和导热性能的影响。结果表明,极少量的MWCNTs对MWCNTs-WS₂/EPDM复合材料在25℃时的非线性电导特性起到明显的增强作用,且随着MWCNTs含量的增加,复合材料非线性电导特征有明显的规律性变化;由于MWCNTs自身的高电导率和电导正温度系数效应,MWCNTs-WS₂/EPDM复合材料电导率随电场强度的变化趋势在80℃时不再表现非线性特征。另外,极少量的MWCNTs对MWCNTs-WS₂/EPDM复合材料的热导率有明显地改善。      

碳纳米管复合亚麻纤维柔性传感材料的制备

导电的碳纳米管(CNTs)与不导电的亚麻纤维(CEL)相结合,可以得到柔性导电复合材料。拉伸或弯曲该材料对其导电性能影响很大。根据电阻变化率(ΔR/R₀)可以敏锐地检测到材料形状的变化,因此CNTs/CEL复合材料适用于柔性传感器。用NaOH/尿素水体系处理亚麻纤维,得到CEL浆,再与不同浓度的CNTs悬浊液混合、抽滤、干燥,制得了CNTs/CEL复合材料。用XRD、FTIR和SEM分析了CNTs/CEL复合材料的结构形态。将CNTs/CEL复合材料制成形变传感器,用拉伸导电性能测试了拉伸对传感器导电性能的影响;将传感器应用到手指关节上,用电阻变化监测了手指弯曲时传感器的形变敏感性。结果发现,随着拉伸应变的增加,CNTs/CEL传感器的电阻变化率ΔR/R₀逐渐增大,50%应变下,ΔR/R₀达到980以上,能灵敏地感知到形状的变化;随着手指关节弯曲程度的增加,CNTs/CEL传感器电阻随之增大,手指最大程度弯曲时,CNTs/CEL传感器电阻可以达到12000 Ω以上,而且重复性良好。      

纳米TiO2对木纤维/聚丙烯复合材料抗紫外老化性能的影响

木塑复合材料作为室外建筑装饰材料时,暴露在紫外光的照射下,易老化导致其力学性能降低、使用寿命减少。将具有高效紫外线屏蔽能力的金红石型纳米TiO₂经硅烷偶联剂KH-570表面改性后,与木纤维(WF)、聚丙烯(PP)等制备了TiO₂-WF/PP复合材料。对TiO₂-WF/PP复合材料进行了人工加速紫外老化,并利用FTIR、TG、SEM、力学性能分析、颜色变化分析等手段,探究了纳米TiO₂对WF/PP复合材料抗紫外老化的影响。结果表明:改性纳米TiO₂粒子在WF/PP复合材料中均匀分散,无明显团聚,且其加入显著提高了复合材料的热稳定性;TiO₂-WF/PP复合材料随着老化时间的延长,力学性能下降相对较小且颜色变化较小。当纳米TiO₂的质量分数为2 wt%~3 wt%,老化2 000 h时后,TiO₂-WF/PP复合材料的拉伸强度、冲击强度仅分别下降10.0%和12.6%;未加入纳米TiO₂颗粒的WF/PP复合材料,则分别下降20.2%和22.6%。      

TiO2/静电纺PAN基碳复合材料的制备及光催化性能

为了同时提高催化剂的光催化和回收能力,以聚丙烯腈(PAN)和钛酸四丁酯(TBT)作为碳纳米纤维(CNFs)和TiO₂前驱体,通过静电纺丝和热处理方法制备了TiO₂/CNFs复合材料,并通过SEM、XRD、Raman、UV-vis分光光度计等对TiO₂/CNFs复合材料的形貌、晶体结构、光吸收性能、导电性和光催化性能进行了研究。结果表明:随TBT添加量的逐渐增多,TiO₂/CNFs复合材料在热处理过程中卷曲形态逐渐消失,并且TBT在碳化过程中完全转化为锐钛矿TiO₂;TiO₂/CNFs复合材料光吸收边缘由纯TiO₂的紫外光区扩展至可见光区,提高了催化剂对太阳光的利用率;同时,在模拟太阳光照射180 min,TiO₂/CNFs复合材料对RhB的光催化降解率最大可达到95.71%,并且在连续重复使用5次后光催化降解效率仍可达到约90%。      

碳纳米管膜层间改性碳纤维/双马来酰亚胺复合材料的结构调控及性能

对比研究了热塑性层间增韧和碳纳米管(CNT)膜层间混杂碳纤维(CF)/双马来酰亚胺复合材料不同层间结构调控方法,分析了其复合材料的压缩、动态力学、导电和电磁屏蔽等性能的变化。结果表明,热密实可显著降低层间CNT膜的厚度,抑制其局部富树脂程度,CNT膜-CF混杂复合材料的压缩强度得以提升,其压缩断口形貌明显不同于初始的CF复合材料。对比而言,热塑性树脂层间增韧CF复合材料的压缩强度明显低于CNT膜/CF混杂复合材料。CNT膜的加入贯通了混杂复合材料的层间导电通路,其厚度方向电导率提高了3个数量级,然而不同复合材料的体积电导率则表现出明显的“木桶效应”。值得关注的是,CNT膜层间混杂对提高CF复合材料的电磁屏蔽特性作用显著,其中致密CNT膜混杂复合材料的电磁屏蔽效能可达到90 dB。      

聚乙烯亚胺修饰富勒烯的制备及其对聚丙烯热氧稳定性的影响

利用聚乙烯亚胺(PEI)分子中活泼的?NH?与富勒烯(C₆₀)结构中C=C键之间的加成反应,制备了PEI修饰C₆₀杂化物(C₆₀?PEI),并采用FTIR、TEM等测试方法对C₆₀?PEI的分子结构和形态进行表征。采用熔融共混法制备了C₆₀?PEI/聚丙烯(PP)复合材料,并对其热性能和阻燃性能进行研究。热失重分析结果表明,C₆₀?PEI可以更有效地发挥C₆₀的自由基捕捉作用,对PP热稳定性的提高效果较C₆₀更明显;氧化诱导测试(OIT)结果表明,C₆₀?PEI/PP复合材料比C₆₀/PP复合材料具有更优异的抗氧性能;微型量热测试也表明,燃烧过程中C₆₀?PEI/PP复合材料比C₆₀/PP复合材料具有更低的热释放量。      

高效CdS量子点敏化B/S共掺杂纳米TiO2太阳能电池的制备及光电性能研究

采用水热法制备硼硫(B/S)共掺杂纳米二氧化钛(B-S-TiO₂), 并配制成浆料, 利用丝网印刷技术在FTO导电玻璃上制备B-S-TiO₂薄膜; 用化学浴沉积(CBD)法制备了CdS量子点敏化B-S-TiO₂薄膜电极, 并用X射线衍射(XRD)、电子显微镜(TEM)、元素分析能谱(EDS)和紫外-可见光谱对其进行表征分析; 结果显示: B/S共掺杂不会改变TiO₂的晶型, 掺杂后的TiO₂吸收边带发生明显红移, 吸收强度显著增强; 同样用化学浴沉积的方法制备NiS工作电极, 用改性的聚硫化物((CH₃)₄N)₂S/((CH₃)₄N)₂S_n)电解液, 组装CdS量子点敏化硼硫(B/S)共掺杂纳米二氧化钛(B-S-TiO₂)太阳能电池, 并测试电池光电性能。测试结果表明, 在AM1.5G的照射下, 电池的能量转化效率(η)由3.21%增大到3.69%, 提高了14.9%, 电池获得高达 (V_oc)1.218 V的开路电压和3.42 mA/cm²的短路光电流(J_sc), 以及高达88.7%的填充因子(ff)。     

碳纳米管/聚丙烯腈基复合材料的热导率研究

采用原位聚合法制备了碳纳米管/聚丙烯腈(CNT/PAN)复合材料,用MDSC的测试方法研究了复合材料的热性能,并由此推导了复合材料的热导率.应用Cheng-Vachon、Nielsen-Lewis和Okamoto-Ishida 3种导热理论模型对CNT/PAN复合材料的热导率进行估算.对比实验测试与导热理论模型的计算结果,考虑到碳纳米管在聚合物基体中的分散和取向情况,得出Nielsen-Lewis理论在低填充含量及室温条件下可以较准确地估算无规分散的CNT/PAN复合材料体系的热导率.     

Properties of polypropylene composites containing aluminum/multi-walled carbon nanotubes

Polypropylene/aluminum–multi-walled carbon nanotube (PP/Al–CNT) composites were prepared by a twin-screw extruder. The morphology indicates that the CNTs are well embedded or implanted within Al-flakes rather than attached on the surface. During preparation of composites, the CNTs came apart from Al–CNT so that free CNTs as well as Al–CNT were observed in PP/Al–CNT composite. The crystallization temperatures of PP/CNT and PP/Al–CNT composites were increased from 111 °C for PP to 127 °C for the composites. The decomposition temperature increased by 55 °C for PP/CNT composite and 75 °C for PP/Al–CNT composite. The PP/Al–CNT composite showed higher thermal conductivity than PP/CNT and PP/Al-flake composites with increasing filler content. PP/Al–CNT composites showed the viscosity values between PP/CNT and PP/Al-flake composites. PP/Al–CNT composite showed higher tensile modulus and lower tensile strength with increasing filler content compared to PP/CNT and PP/Al-flake composites.     

The effect of geometric factor of carbon nanofillers on the electrical conductivity and electromagnetic interference shielding properties of poly(trimethylene terephthalate) composites: a comparative study

In this study, the effects of filler geometry on the electrical conductivity and electromagnetic interference (EMI) shielding properties of poly(trimethylene terephthalate) (PTT) composites filled with graphene nanosheets (GNSs), carbon nanotubes (CNTs), and GNS–CNT hybrid nanofillers have been investigated. The GNSs, CNTs, and hybrid GNS–CNT were well dispersed in the PTT matrix using a simple coagulation process. GNSs were prepared from graphene oxide (GO) through hydrazine reduction, and thermal reduction of GO at two different temperatures of 1050 and 1500 °C. PTT filled with different aspect ratios and oxygen functional groups of GNS were also prepared in order to compare the electrical conductivity and EMI shielding properties. The aspect ratios of GNSs and CNTs were estimated by using an ellipsoid model. Percolation scaling laws were applied to the magnitudes of conductivity to reveal the percolation network and filler dispersion. The percolation exponent of the PTT/GNS composites was larger than that of the PTT/CNT composites. The percolated filler–filler network at which the percolation exponent changed was correlated with the filler geometric structure. GNS–CNT hybrid nanofillers formed a complex double brush structure in the PTT/GNS–CNT composites. The geometric structure, aspect ratio, and intrinsic conductivity of carbon nanofillers affected the electrical percolation threshold and EMI shielding efficiency of the composites.     

Thermal Conductivity Behavior of Carbon Nanotubes Reinforced Copper Matrix Composites

Carbon nanotubes (CNT) exhibit excellent thermal conductivity.Therefore they are potential reinforcements in composites materials for thermal management applications,where high thermal conductivity and low coefficient of thermal expansion (CTE) are required.In the present study,CNT/Cu composites containing CNTs varying from 0 vol.％ to 15 vol.％ were prepared,and their thermal conductivity behavior was studied in detail.The results indicated that the thermal conductivity of the composites shows no enhancement by the incorporation of CNTs.The presence of interfacial thermal resistance and high level of porosity are the main reasons for this low thermal conductivity.The well dispersed 0-10 vol.％ CNTs composites show a very close to the thermal conductivity of Cu.However,the addition of 15 vol.％ CNTs results in a rather low thermal conductivity of CNT/Cu composites due to the presence a high level of porosity induced by the formation of CNT clusters.The present paper also claims that a further substantial enhancement in thermal conductivity is only possible if the nanotubes are randomly oriented in the plane or if they are all aligned in one direction,for which the processing of CNTs-aligning in metal matrix should be developed.     

Fabrication and effective thermal conductivity of multi-walled carbon nanotubes reinforced Cu matrix composites for heat sink applications

A novel particles-compositing method was used for the first time to disperse different contents of multi-walled carbon nanotubes (CNTs) in micron sized copper powders, which were subsequently consolidated into CNT/Cu composites by spark plasma sintering (SPS). Microstructural observations showed that the homogeneous distribution of CNTs and dense composites could be obtained for 0–10 vol.% CNT contents. The CNT clusters were appeared in the powder mixture with 15 vol.% CNTs, which resulted in an insufficient densification of the composites. The effective thermal conductivity of the composites was analyzed both theoretically and experimentally. The addition of CNTs showed no enhancement in overall thermal conductivity of the composites due to the interface thermal resistance associated with the low phase contrast of CNT to copper and the random tube orientation. Besides, the composite containing 15 vol.% CNTs led to a rather low thermal conductivity due possiblely to the combined effect of unfavorable factors induced by the presence of CNT clusters, i.e. large porosity, lower effective conductivity of CNT clusters themselves and reduction of SPS cleaning effect. The CNT/Cu composites may be a promising thermal management material for heat sink applications.     

添加纳米碳管对高密度聚乙烯力学行为和结晶过程的影响

利用熔融法制备了一系列具有不同纳米碳管含量的纳米碳管(Q盯)／高密度聚乙烯(HDPE)复合材料。对其拉伸性能的研究结果表明，添加质量分数分别为2％，5％和10％的纳米碳管使HDPE的拉伸模量分别提高了7．4％，27．0％和28．6％，屈服强度分别提高了3．3％，14．4％和18．5％，但是会降低HDPE的断裂强度和断裂伸长率。同时，对复合材料中HDPE结晶过程的研究表明，纳米碳管可以提高HDPE的开始结晶温度，降低结晶活化能，但是会使HDPE的结晶速率下降，结晶度降低。     

The effect of nanotube surface oxidation on the electrical properties of multiwall carbon nanotube/poly(vinylidene fluoride) composites

Carbon nanotube/poly(vinylidene fluoride) (CNT/PVDF) composites were prepared using CNT with different oxidation and thermal treatments. The oxidation procedure leads to CNT with the most acidic characteristics that lower the degree of crystallinity of the polymer and contribute to a large increase of the dielectric constant. The surface treatments, in general, increase the percolation threshold and decrease conductivity. The surface treatments do not seem to affect CNT interactions and similar degrees of dispersion are achieved in all cases, as shown by the SEM results. The maximum value of the dielectric constant is ~630. It is demonstrated that the composite conductivity can be attributed to a hopping mechanism that is strongly affected by the surface treatment of the CNT.     

聚苯胺/碳纳米管的原位复合

通过原位溶液聚合制备了聚苯胺/碳纳米管(PANI/CNT)复合材料。采用透射电子显微镜(TEM)、紫外-可见光光谱(UV-VIS)、傅立叶变换红外光谱(FTIR)、热失重分析(TGA)及差示扫描量热法(DSC)研究了PANI/CNT复合材料的结构与性能。研究表明,苯胺(ANI)的聚合倾向于在碳纳米管(CNT)表面进行,形成PANI包覆的CNT。CNT表面PANI层的厚度随溶液中ANI含量的增加而增加;当溶液中ANI含量较低时,CNT表面PANI层厚度均匀;当ANI含量过高时,CNT表面PANI层厚度不均匀,形成一些颗粒状附着物。PANI与CNT之间主要是物理吸附;PANI/CNT复合材料的电导率远高于PANI本身。同时,PANI/CNT复合材料的耐热性远高于PANI,并受PANI含量影响。     

Morphology and thermal conductivity of polyacrylate composites containing aluminum/multi-walled carbon nanotubes

Polyacrylate composites with various fillers such as multi-walled carbon nanotube (CNT), aluminum flake (Al-flake), aluminum powders and Al–CNT were prepared by a ball milling. The thermal decomposition temperature increased by as much as 64 °C for polyacrylate/Al-flake 70 wt% composite compared to polyacrylate. The thermal conductivity of polyacrylate/Al–CNT composites increased from 0.50 to 1.67 W/m K as the Al–CNT content increases from 50 to 80 wt%. The thermal conductivity of the composite sheet increases with the sheet thickness. At the given filler concentration (90 wt%), the composite filled with aluminum powder of 13 μm has a higher thermal conductivity than the one filled 3 μm powder, and the composite filled with mixture of two powders showed a synergistic effect on the thermal conductivity. The morphology indicates that the dispersion of CNT in the polyacrylate/Al-flake + CNT composite is not perfect, and agglomeration of CNTs was observed.