MWCNTs/PVC电纺纤维及其力学性能

用静电纺技术制备了多壁碳纳米管/聚氯乙烯(MWCNTs/PVC)超细纤维,对复合纤维的形貌、结构、结晶行为及热稳定性进行了分析测试,着重研究了复合纤维膜的力学性能与MWCNTs用量的关系。结果表明,MWCNTs能有效地分散于PVC溶液中,并成功纺出MWCNTs/PVC超细纤维。随着MWCNTs含量的增加,纤维直径变细,改善了纤维的结晶性,但热稳定性变差。纤维膜的拉伸断裂强度和断裂伸长率随MWCNTs含量增加出现先增加后下降的趋势。     

空气过滤用静电纺聚苯乙烯/碳纳米管复合纤维膜的制备

采用静电纺丝技术制备聚苯乙烯(PS)超细纤维、PS/多壁碳纳米管(MWCNTs)复合纳米纤维,并对其纤维形态结构、直径大小及空气过滤性能进行了表征。通过PS纺丝溶液浓度变化调控制备纯PS纤维多孔膜,并通过在PS纺丝液中添加不同含量MWCNTs调控纤维形态结构。SEM分析结果表明PS/MWCNTs复合纤维表面形成"褶皱"型和"山峰"型纳米级突起,复合纤维表面的粗糙度明显增加,且纤维直径明显减小。空气过滤性能测试结果发现这种多级结构使复合膜的过滤效率相比光滑的纯PS纳米纤维膜大幅提高,过滤性能得到明显改善。在85L/min气流速度下,PS/MWCNTs复合膜过滤效率高达99.95%,空气阻力为374.6Pa。选择尺寸较粗的微米级PS纤维(~2μm)和相对较细的纳米级PS/MWCNTs复合纤维(~800nm)进行混纺,调节复合膜堆积密度可使得混纺膜空气阻力降低到235.4Pa,仍能保持高的过滤效率(99.68%)。     

Lyocell/多壁碳纳米管复合纤维的制备及性能

将多壁碳纳米管(MWCNTs)水悬浮液、N-甲基吗啉-N-氧化物(NMMO)溶液及纤维素共混得到纺丝液,通过干湿法制备了Lyocell/MWCNT复合纤维。采用X-衍射仪(WAXD)、扫描电镜(SEM)、透射电镜(TEM)、强度仪等分析了所得纤维的结构和性能。WAXD图谱显示复合纤维仍然具有纤维素II晶型的结构,同时还保留了MWCNTs的特征衍射峰;二维X衍射结果表明:MWCNTs质量分数为5%的复合纤维中,MWCNTs与纤维轴的取向角为±15.2°,说明复合纤维中MWCNTs基本沿着纤维轴取向。SEM结果显示复合纤维中MWCNTs在Lyocell基体中分布均匀。对纤维的力学性能分析进一步表明:添加适量的MWCNTs可使复合纤维的力学性能提高,MWCNTs质量分数为1%的复合纤维的初始模量和强度分别比Lyocell纤维增加49.4%和15.7%。     

碳纳米管的表面改性及在铜基复合材料中的应用

对碳纳米管进行表面改性,能够显著提高碳纳米管的表面活性、分散稳定性及与基材的结合性,提高其在复合材料中的增强效果。以电化学制备石墨烯量子点(GQDs)作为分散剂和交联剂,对多壁碳纳米管表面(MWCNTs)进行非共价键改性得到MWCNTs/GQDs复合材料。并将改性后的MWCNTs/GQDs复合材料与商品化超细铜粉进行复合,得到具有良好导电性和抗氧化性的铜基复合材料(MWCNTs/GQDs/Cu)。结果表明,水溶液中,GQDs通过π-π键吸附在MWCNTs表面,使MWCNTs的稳定浓度高达1.0 g/L。3.0%(质量分数)的MWCNTs/GQDs复合材料与商品化超细铜粉复合后,其电导率提高5.67%IACS,抗氧化温度提高53.0℃。     

热处理对电纺聚己内酯超细纤维形态和性能的影响

通过静电纺丝法制备出聚己内酯(PCL)超细纤维膜,并采用热处理方法使纤维间粘接。用扫描电镜、红外光谱仪、X射线衍射仪、差示扫描量热仪对热处理前后聚己内酯超细纤维进行表征,并进行了拉伸测试。结果表明,在55℃对电纺聚己内酯超细纤维热处理30min、60min后,纤维间有明显的粘接,热处理没有改变电纺聚己内酯超细纤维的分子结构和晶型,热处理后纤维的结晶度提高,纤维膜的力学性能有明显改善。     

功能化碳纳米管的制备及功能化碳纳米管/尼龙6复合纤维

采用多聚磷酸(PPA)/P₂O₅弱酸体系, 通过傅克反应(Friedel-Crafts reaction)对多壁碳纳米管(MWCNTs)进行功能化改性, 加入己内酰胺后采用原位聚合法制备功能化碳纳米管(F-MWCNTs)/尼龙6(PA6)复合材料, 并熔融纺丝制备复合纤维。通过TEM、TG、DSC、SEM及力学性能测试对复合纤维进行表征。结果表明: 在MWCNTs表面成功地接枝了氨基, F-MWCNTs均匀地分散在PA6基体中, 没有发生团聚现象, 并且与基体具有很好的界面作用; F-MWCNTs的加入, 对复合纤维的熔融温度和结晶度影响不大, 结晶温度有所提高, 并明显提高了复合纤维的热稳定性; 随着F-MWCNTs的加入, 复合纤维的拉伸断裂强度和杨氏模量增加, 当F-MWCNTs质量分数为0.5%时, 拉伸断裂强度和杨氏模量达到最大, 比纯PA6纤维分别提高了45%和208%。     

静电纺丝制备MWCNTs/PVA定向导热复合纤维膜

将浓HNO₃和浓H₂SO₄酸化处理后的多壁碳纳米管(MWCNTs)加入聚乙烯醇(PVA)纺丝液中，通过静电纺丝法制备了不同MWCNTs含量的MWCNTs/PVA复合纤维膜。FT-IR分析表明，酸化后的MWCNTs表面含有大量羟基和羧基。TEM分析表明，MWCNTs在PVA内部呈定向线性排列。有效导热通道的形成，使得MWCNTs/PVA复合纤维膜的水平导热系数显著增大，5%MWCNTs/PVA的水平导热系数为1.32W/(m·K),为纯PVA纤维膜导热系数的6.6倍。同时，MWCNTs的添加提高了复合纤维膜的热稳定性，5%MWCNTs/PVA的热分解温度达到295.7℃,比纯PVA纤维膜提高了14.4℃。利用红外热像仪探测了MWCNTs/PVA复合纤维膜应用于LED灯的散热效果，5%MWCNTs/PVA纤维膜能有效降低LED灯珠的附近温度约11℃。     

多壁碳纳米管/聚乳酸复合超细纤维的制备及性能

通过静电纺丝法制备出多壁碳纳米管（MWNTs）增强聚乳酸（PLA）复合超细纤维膜。用扫描电镜、透射电镜、差示扫描量热仪、热重分析仪对MWNTs/PLA复合超细纤维进行了表征,并进行了拉伸测试。结果表明,MWNTs分散于PLA纤维中,随着MWNTs含量的增加,纤维平均直径先减小后增大,MWNTs的加入会降低PLA的结晶度...     

静电纺丝制备聚己内酯/壳聚糖复合纤维膜

采用静电纺丝技术制备聚己内酯(PCL)/壳聚糖(CS)复合纤维膜,利用扫描电子显微镜(SEM)观察材料配比、纺丝电压和接收距离对复合纤维形态的影响,利用接触角测试仪研究CS含量对复合纤维膜亲水性能的影响。结果表明:CS的加入,有利于提高PCL/CS混合溶液的成纤能力;随着纺丝电压增加和收集距离减小,复合纤维平均直径减小,且直径分布均匀性提高。与PCL纤维相比,PCL/CS复合纤维亲水性得到了较大的提高,使其有望在组织工程中得到潜在的应用。     

纳米羟基磷灰石/丝素蛋白/聚己内酯复合超细纤维的制备及表征

通过静电纺丝法制备出纳米羟基磷灰石/丝素蛋白/聚己内酯复合超细纤维,利用扫描电镜、红外光谱仪、X射线衍射仪对纳米羟基磷灰石/丝素蛋白/聚己内酯复合超细纤维形貌和结构进行表征,并进行了拉伸测试。结果表明,随着超细纤维中羟基磷灰石含量的增加,纤维的直径逐渐降低,纤维中聚己内酯的结晶逐渐变差。相比于丝素蛋白/聚己内酯超细纤维,含有质量比为30%羟基磷灰石的复合超细纤维仍具有较好的力学性能。体外小鼠成纤维细胞(L929)培养表明,纳米羟基磷灰石/丝素蛋白/聚己内酯复合超细纤维对细胞没有毒性。     

Preparation,characterization and properties of polycaprolactone diol-functionalized multi-walled carbon nanotube/thermoplastic polyurethane composite

Multi-walled carbon nanotubes (MWCNTs) were chemically functionalized to prepare thermoplastic polyurethane (PU) composites with enhanced properties. In order to achieve a high compatibility of functionalized MWCNTs with the PU matrix, polycaprolactone diol (PCL), as one of PU’s monomers, was selectively grafted on the surface of MWCNTs (MWCNT–PCL), while carboxylic acid groups functionalized MWCNTs (MWCNT–COOH) and raw MWCNTs served as control. Both MWCNT–COOH and MWCNT–PCL improved the dispersion of MWCNTs in the PU matrix and interfacial bonding between them at 1 wt% loading fraction. The MWCNT–PCL/PU composite showed the greatest extent of improvement, where the tensile strength and modulus were 51.2% and 33.5% higher than those of pure PU respectively, without sacrificing the elongation at break. The considerable improvement in both mechanical properties and thermal stability of MWCNT–PCL/PU composite should result from the homogeneous dispersion of MWCNT–PCL in the PU matrix and strong interfacial bonding between them.     

High performance natural rubber composites with a hierarchical reinforcement structure of carbon nanotube modified natural fibers

A simple and facile method for depositing multiwall carbon nanotubes (MWCNTs) onto the surface of naturally occurring short jute fibers (JFs) is reported. Hierarchical multi-scale structures were formed with CNT-networks uniformly distributed and fully covering the JFs (JF–CNT), as depicted by the scanning electron microscopy (SEM) micrographs. The impact of these hybrid fillers on the mechanical properties of a natural rubber (NR) matrix was systematically investigated. Pristine JFs were cut initially to an average length of 2.0 mm and exposed to an alkali treatment (a-JFs) to remove impurities existing in the raw jute. MWCNTs were treated under mild acidic conditions to generate carboxylic acid moieties. Afterward, MWCNTs were dispersed in an aqueous media and short a-JFs were allowed to react with them. Raman spectroscopy confirmed the chemical interaction between CNTs and JFs. The JF–CNT exposed quite hydrophobic behavior as revealed by the water contact angle measurements, improving the wettability of the non-polar NR. Consequently, the composite interfacial adhesion strength was significantly enhanced while a micro-scale “mechanical interlocking” mechanism was observed from the interphase-section transmission electron microscopy (TEM) images. SEM analysis of the composite fracture surfaces demonstrated the interfacial strength of NR/a-JF and NR/JF–CNT composites, at different fiber loadings. It can be presumed that the CNT-coating effectively compatibillized the composite structure acting as a macromolecular coupling agent. A detailed analysis of stress-strain and dynamic mechanical spectra confirmed the high mechanical performance of the hierarchical composites, consisting mainly of materials arising from natural resources.     

纳米羟基磷灰石/玉米醇溶蛋白复合超细纤维的制备与性能

利用静电纺丝制备出纳米羟基磷灰石(nHA)/玉米醇溶蛋白(zein)复合超细纤维。通过场发射扫描电镜、透射电镜观察了纳米羟基磷灰石/玉米醇溶蛋白复合超细纤维的形貌;利用红外光谱仪、X射线衍射仪对纳米羟基磷灰石/玉米醇溶蛋白复合超细纤维结构和性能进行表征,并进行了拉伸测试。结果表明,随着超细纤维中羟基磷灰石含量的增加,纤维的直径先减小后增大,纤维中纳米羟基磷灰石的结晶逐渐变好。相比于玉米醇溶蛋白超细纤维,含有质量分数为25%羟基磷灰石的复合超细纤维仍具有较好的力学性能。     

水相悬浮聚合制备MWCNTs/PAN复合微球及其电纺纤维

先用Fenton试剂（过氧化氢/硫酸亚铁）对多壁碳纳米管进行改性处理（-fMWCNTs）,再通过水相悬浮聚合法制备了多壁碳纳米管/聚丙烯腈（-fMWCNTs/PAN）复合微球,用静电纺丝技术制备了-fMWCNTs/PAN复合纤维膜。通过扫描电镜（SEM）、热重分析仪（TGA）和万能试验机研究了-fMWCNTs对电纺纤维...     

Effect of polyphosphazene and modified carbon nanotubes on the morphological and thermo-mechanical properties of polyphenylene sulfide and liquid crystalline polymer blend system

Ternary blends of polyphenylene sulfide (PPS) and liquid crystalline polymer (LCP) with either polyphosphazene, unmodified multiwall carbon nanotubes (MWCNTs) or SiC-coated MWCNTs, were prepared by melt blending. While polyphosphazene improved the compatibility between the PPS and LCP, unmodified MWCNTs promoted LCP domain deformation, from spherical to ellipsoidal. Long LCP fibers were formed in presence of SiC-coated MWCNTs due to the bridging effect of modified MWCNTs at the interface of PPS and LCP. This bridging effect was confirmed by field emission scanning electron microscopy (FESEM). The better dispersion of SiC-coated MWCNTs was confirmed by both FESEM and transmission electron microscopy analysis. The superior mechanical properties of SiC-coated MWCNTs added blend system can be attributed to the fibrillation of LCP and better dispersion of SiC-coated MWCNTs. Polyphosphazene containing blend system showed lowest thermal stability while blend with SiC-coated MWCNTs was found to be highest, among all the blend systems.     

Influence of ultrasonic dual mixing on thermal and tensile properties of MWCNTs-epoxy composite

Multiwalled carbon nanotubes (MWCNTs) reinforced epoxy based composites were fabricated by using an innovative ultrasonic dual mixing (UDM) process consists of ultrasonic mixing with simultaneous magnetic stirring. The effect of addition of varying amount of MWCNTs on thermal stability and tensile properties of the epoxy based composite has been investigated. It is found that the thermal stability, tensile strength and toughness of the epoxy base improves with the increase of MWCNTs addition up to 1.5 wt.% and UDM processing at certain capacity of the system. Tensile tests and thermal gravimetric analysis (TGA) were performed on each group of composites containing different amount of MWCNTs to determine their mechanical and thermal properties respectively. The dispersion of 1.5 wt.% MWCNTs fillers in epoxy nanocomposites was studied by transmission electron microscopy (TEM) as well as by field emission scanning electron microscopy (FESEM) applied on their tensile fracture surface.