碳化硅改性PU弹性体复合材料的研究

采用超声波技术对碳化硅表面进行有机处理,并将其分散到甲苯二异氰酸酯(TDI)体系内,在其表面进行原位聚合,制得了聚氨酯弹性体复合材料.SEM分析表明碳化硅在聚氨酯弹性体中具有良好的分散性.力学测试结果表明,5%～10%碳化硅添加量会使复合材料的力学性能、耐磨性、耐溶剂性能最好.     

SDBS修饰碳纳米管及其增强聚乳酸复合材料的制备与表征

采用十二烷基苯磺酸钠(SDBS)对碳纳米管进行表面修饰,并以其为增强体,利用溶剂蒸发法制备了碳纳米管/聚乳酸复合材料.采用红外吸收光谱、偏光显微镜、扫描电镜及拉伸实验研究了SDBS修饰的碳纳米管表面形貌和结构以及碳纳米管/聚乳酸复合材料的链结构、聚集态结构和力学性能.SDBS修饰可使碳纳米管均匀分散于有机溶剂中,并改善...     

碳纳米管／聚氨酯纳米复合材料的制备及性能

采用可逆加成-断裂链转移(RAFT)聚合方法在碳纳米管表面接枝聚甲基丙烯酸甲酯和聚苯乙烯嵌段共聚物MWNT-P(MMA-b-St),对碳纳米管进行改性。采用直接共混法制备碳纳米管/水性聚氨酯纳米复合材料。通过红外光谱(FT-IR)和透射电镜(TEM)对嵌段共聚物的结构进行了表征。碳纳米管加入对乳液成膜性影响不大。热失重分析(TGA)和力学性能测试结果表明,当改性后的碳纳米管含量为聚氨酯固体份的0.75%时,复合材料的热稳定性、拉伸强度和断裂伸长率均较聚氨酯有所提高。     

碳纳米管在聚合物中的分散性研究

碳纳米管在聚合物中的分散性是影响碳纳米管/聚合物复合材料性能的最重要因素之一.综述了碳纳米管/聚合物复合材料制备过程中碳纳米管的分散方法,主要有化学方法(如表面化学修饰法、辐照接枝法、表面改性剂法)和物理方法(如超声分散法、机械分散法),对各种方法的机理和研究现状进行了分析与讨论.     

碳纳米管/聚合物基复合材料的研究进展

简要介绍了碳纳米管的结构及其分散性,说明碳纳米管具有一维结构及中空的内部结构,极高的化学稳定性,易于团聚.影响碳纳米管分散体系稳定性的关键是空间效应,所以末端亲水基团的结构和性能将明显影响碳纳米管的分散.碳纳米管在基体中的良好分散使复合材料力学性能大幅度提高,并且由于其优良的光电性能,加入碳纳米管也可显著提高复合材料的光电性能和导电性能.此外,碳纳米管石墨层的本质及独特的结构和尺寸,使碳纳米管在提高复合材料的热性能方面也有很大贡献.     

多壁碳纳米管/环氧树脂聚合物热电和力学性能实验研究EI

通过比较多壁碳纳米管在不同溶剂中的分散性,优选出(N,N-DMF)表面活性剂和甲醇的混合液,来超声分散碳纳米管,制备成碳纳米管增强的环氧树脂基聚合物.电学和摩擦性能测试表明,随碳纳米管含量的增加,复合材料的体积电阻率呈几何量级的降低,摩擦系数近线性降低.常温下力学性能测试表明,随着碳纳米管含量的增加,其弹性模量先增后降.在50℃时,对于碳纳米管含量≤1%(质量分数,下同)的复合材料,经历了可逆的粘弹性阶段后进入了塑性变形,且温度对复合材料的弹性模量和拉伸强度影响较大;而对于碳纳米管含量＞1%的复合材料,其力学性能反而发生退化.     

多壁碳纳米管/环氧树脂聚合物热电和力学性能实验研究

通过比较多壁碳纳米管在不同溶剂中的分散性,优选出(N,N-DMF)表面活性剂和甲醇的混合液,来超声分散碳纳米管,制备成碳纳米管增强的环氧树脂基聚合物.电学和摩擦性能测试表明,随碳纳米管含量的增加,复合材料的体积电阻率呈几何量级的降低,摩擦系数近线性降低.常温下力学性能测试表明,随着碳纳米管含量的增加,其弹性模量先增后降.在50℃时,对于碳纳米管含量≤1%(质量分数,下同)的复合材料,经历了可逆的粘弹性阶段后进入了塑性变形,且温度对复合材料的弹性模量和拉伸强度影响较大;而对于碳纳米管含量＞1%的复合材料,其力学性能反而发生退化.     

混杂功能化碳纳米管/聚氨酯复合材料的制备及性能

以多壁碳纳米管（MWNTs）为原料,采用不同改性方法制得了羧化碳纳米管（MWNTs-COOH）、共价功能化碳纳米管（MWNTs-NH₂）、非共价功能化碳纳米管（MWNTs-PPA）和混杂功能化碳纳米管（MWNTs-COOH-PPA）,将这4种改性碳纳米管按不同质量分数分别加入聚氨酯（PU）中制备了复合材料。使用万能材料试验机和热失重分析仪测试了复合材料的力学和热学性能,研究了碳纳米管对复合材料性能的影响。结果表明:通过在碳纳米管表面接枝少量的共价官能团防止非共价包覆的剥离,混杂功能化方法既能够改善碳纳米管在基体中的分散性,又能够保持其与基体界面间结合力,复合材料增强效果最明显。耐热性良好的碳纳米管的添加提高了PU基体的热分解温度,提高程度由于其功能化方式的不同而稍有差别。MWNTs-COOH-PPA/PU复合材料的力学性能最优,当碳纳米管含量（质量分数,下同）为0.3%时,其拉伸强度与纯PU相比提高104%,其热分解温度与MWNTs-COOH/PU相当,优于纯PU,但低于MWNT8-NH₂/PU和MWNTs-PPA/PU。     

碳纳米管表面处理及其在铜基复合材料中的应用

碳纳米管因特殊结构带来的优异性能而被海内外学者广泛关注,以碳纳米管为增强相制备铜基复合材料是使铜基导体同时具有高强度和高导电性能的有效途径。然而,由于碳纳米管表面能高、表面反应活性低,碳纳米管/铜复合材料制备的过程中存在增强体分散性差和界面结合强度弱两大问题,从而阻碍了复合材料高性能的实现。在碳纳米管/铜复合材料的制备过程中,采用适当的方法对碳纳米管进行表面处理能改变碳纳米管的表面结构和反应活性,在改善碳纳米管的分散性的同时增强碳纳米管与铜基体的界面结合,从而提高碳纳米管的增强效率,保证复合材料良好的综合性能。然而,表面处理过程可能会破坏碳纳米管的结构完整性,影响碳纳米管的本征性能,进而影响其增强效果,或可能在基体中引入其他杂质,影响复合材料的导电和导热性能。因此,在进行表面处理时应综合考虑其对碳纳米管结构性能及复合材料增强作用的影响。近年来,研究者们通过优化碳纳米管表面处理工艺突破了碳纳米管/铜复合材料在制备过程的难点,在保证铜基体优异的导电、导热性能的同时,大幅提高了碳纳米管/铜复合材料的力学性能。碳纳米管表面处理工艺类型大致可分为机械球磨、化学表面改性、表面镀层和联合表面处理四类。传统的机械球磨表面处理对碳纳米管的结构破坏较大;化学表面改性又分为共价表面改性和非共价表面改性,非共价表面改性在保持碳纳米管完整的管状结构和优异性能的同时,提高了碳纳米管在溶液中的分散性,但用于复合材料制备时会给基体引入有机杂质,影响复合材料性能;共价表面改性和表面镀层是铜基复合材料制备过程中最为常用和有效的表面处理方法,其能够在提高碳纳米管在基体中的分散性能的同时改善碳纳米管表面的反应活性,从而形成碳纳米管和铜基体之间强度较高的反应结合界面,实现碳纳米管/铜复合材料高强高导的综合性能。此外,可通过综合利用各种表面处理方法,结合各表面处理工艺的优势,获得更为优异的改性效果。本文从碳纳米管表面处理工艺的基本类型以及碳纳米管表面处理对铜基复合材料结构和性能的影响两方面阐述了碳纳米管表面处理在铜基复合材料中的应用和研究进展,并对其未来的研究方向进行了展望。     

碳纳米管及聚合物复合材料分散性的研究进展

探讨了碳纳米管及其聚合物复合材料分散性的研究进展.综述了碳纳米管功能化修饰和碳纳米管表面处理改性两大方面,阐述了提高碳纳米管分散性的方法,介绍了紫外光谱、拉曼光谱、扫描电子显微镜、透射电子显微镜、原子力学显微镜、差示扫描量热仪等表征方法,表征及分析了碳纳米管的分散状态;同时指出了存在的问题及以后的发展方向.     

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.     

基于聚氨酯的PEDOT核壳分散体的制备及应用

通过在聚氨酯分散体中原位聚合成功制备了以聚氨酯(PU)乳胶粒子为核,聚3,4-乙撑二氧噻吩(PEDOT)为壳的核壳分散体。改变单体EDOT与PU乳胶粒子的质量比,制备了一系列PEDOT-PU复合分散体,并通过红外光谱、透射电镜、动态光散射和四探针测试等手段进行了表征,探讨了核壳粒子形成过程。结果表明,EDOT与PU乳胶粒子质量比为1/10时,复合分散体的综合性能最佳,利用自制的复合分散体配制得到了抗静电涂料,并成功应用于PET、PVC、PP塑料基材。     

聚氨酯/二氧化硅包覆多壁碳纳米管复合材料的导热与电绝缘性能

通过溶胶-凝胶法制备了厚度为30nm-50nm的二氧化硅(SiO2)包覆多壁碳纳米管(SiO2-MWNTs),并与聚氨酯(PU)复合制备了PU/SiO2-MWNT复合材料。研究了SiO2-MWNTs对PU导热电绝缘性能的影响。结果表明,SiO2包覆层增强了MWNTs与PU之间的界面相互作用,促进了MWNTs在PU中的分散。由于SiO2包覆层的电绝缘作用,PU/SiO2-MWNT复合材料保持了PU的电绝缘性能。同时SiO2包覆层作为过渡层,降低了PU与MWNTs间的模量失配,减少了声子的界面散射,提高了PU/SiO2-MWNT复合材料的导热性能。当SiO2-MWNTs的质量分数为0.5%和1.0%时,PU/SiO2-MWNT复合材料的热导率分别提高了53.7%和63.8%。     

Chemical functionalization of graphene oxide for improving mechanical and thermal properties of polyurethane composites

Graphene oxide (GO) was chemically functionalized to prepare polyurethane (PU) composites with improved mechanical and thermal properties. In order to achieve a well exfoliated and stable GO suspension in an organic solvent (dimethylformamide, DMF), 4, 4′-methylenebis(phenyl isocyanate) and polycaprolactone diol, which were the two monomers for synthesizing PU, were selectively used to functionalize GO. The obtained functionalized GO (FGO) could form homogeneous dispersions in DMF solvent and the PU matrix, as well as provide a good compatibility with the PU matrix. The most efficient improvement of mechanical properties was achieved when 0.4 wt.% FGO was added into the PU matrix, showing increases in the tensile stress, elongation at break and toughness by 34.2%, 27.6%, and 64.5%, respectively, compared with those of PU. Regarding the thermal stability, PU filled with 1 wt.% FGO showed the largest extent of improvement with T_2% and T_50% (the temperatures at which 2% and 50% weight-loss happened) 16 °C and 21 °C higher than those of PU, respectively. The significant improvement in both mechanical properties and thermal stability of FGO/PU composites should be attributed to the homogeneous dispersion of FGO in the PU matrix and strong interfacial interaction between them.     

Preparation and dielectric properties of a polyurethane elastomer filled with resol-derived ordered mesoporous carbon

This study deals with the preparation and dielectric properties of polyurethane (PU) elastomer films by resol-derived ordered mesoporous carbon (OMC) nanopowder incorporation in the PU polymer matrix. Resol-derived OMC with a 2D hexagonal mesoporous carbon framework is used as conducting fillers to achieve homogeneous dispersion and favorable interfacial interactions in the polymer matrix. The dielectric properties depend on the applied field frequency and the carbon filler weight fraction. The carbon fraction has little effect on the relative permittivity. The relative permittivity of all the PU-OMC composites increases with the decline of frequency. Incorporating a small amount of OMC into the PU polymer had no influence on the dielectric loss. Along with the increasing carbon fraction above the percolation threshold, dielectric loss of PU-OMC composites increases exponentially in the low frequency range. PU-0.75 wt% OMC composite possesses the best dielectric properties, and the obtained relative permittivity and dielectric loss at 1 kHz is 9.59 and 0.03018, respectively.     

Preparation and properties of polyurethane/zeolite 13X composites

The pre-polymerization method was used to prepare polyurethane/zeolite 13X (PU/13X) composites. The effects of zeolite 13X content and its surface organic modification on the mechanical properties of composites were investigated. It was demonstrated that the mechanical properties of PU/13X composites were better than that of pure PU. The surface organic modification of zeolite 13X had no obvious effect on the mechanical properties of PU/13X composites. The optimal tensile strength and tear strength were obtained with 3–5% and 5–7% zeolite 13X loading, respectively. Thermogravimetric analysis (TGA) results showed that the decomposition temperature of PU/13X composites increased in comparison with pure PU. Dynamic mechanical analyzer (DMA) suggested a lower glass transition temperature (T_g) and better micro-phase separation of soft and hard segments in PU/13X composites. Besides, PU/13X composites had excellent solvent resistance performance.     

聚氨酯(PU)/凹凸棒土(AT)原位复合材料制备及表征

凹凸棒土(AT)经过提纯,采用原位聚合方法制备聚氨酯(PU)/凹凸棒土(AT)复合材料.通过SEM、FT-IR、DMA等测试方法对PU/AT复合材料的结构进行了表征.结果表明:复合材料的热稳定性和玻璃化温度较PU都有明显提高,拉伸强度也有较大提高.并分析了AT对复合材料结构的影响和作用机理.     

Friction and wear behavior of the polyurethane composites reinforced with potassium titanate whiskers under dry sliding and water lubrication

A series of polyurethane (PU)/potassium titanate whiskers (PTW) composites modified by a high molecular weight hydroxyl-terminated polydimethylsiloxane (HTPDMS) were prepared. The PTW is modified by 2,4-diisocyanatotoluene (2,4-TDI). The effect of the PTW content on the mechanical and tribological properties of the PU composites was studied. Tensile strength of the PU composites increased with the addition of PTW. The friction and wear experiments were tested on a MRH-3 model ring-on-block test rig at different sliding speeds and loads under dry sliding and water lubrication. Experimental results revealed that the small content of PTW contributed to largely improve the tribological properties of the PU composites. The coefficient of friction (COF) of the composites increased and the wear rate value decreased with increasing PTW. Scanning electron microscopic (SEM) investigations showed that the worn surfaces of the PTW-reinforced PU composites was smoother than pure polyurethane under given load and sliding speed.     

Thermal conductive and electrical properties of polyurethane/hyperbranched poly(urea-urethane)-grafted multi-walled carbon nanotube composites

Hyperbranched poly(urea-urethane)-grafted multi-walled carbon nanotubes (HPU-MWCNTs) were incorporated in a polyurethane (PU) matrix based on poly(ethylene oxide-tetrahydrofuran) and aliphatic polyisocyanate resin as curing agent. The 9–12 nm thick HPU shell formed on the MWCNTs improved the dispersion of MWCNTs and enhanced the interfacial adhesion between the PU matrix and MWCNTs, leading to improvements in storage modulus and T_g of the composites and enhancement of the thermal stability of PU. Thus, composites with 0.5–1 wt% MWCNTs increased the thermal conductivity by about 60–70% when compared to, and retained the high electrical resistivity of, neat PU.     

Influence of metal nanoparticle decorated CNTs on polyurethane based electro active shape memory nanocomposite actuators

Polymer nanocomposites based on thermoplastic polyurethane (PU) elastomer and metal nanoparticle (Ag and Cu) decorated multiwall carbon nanotubes (M-CNTs) were prepared through melt mixing process and investigated for its mechanical, dynamic mechanical and electro active shape memory properties. Structural characterization and morphological characterization of the PU nanocomposites were done using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Morphological characterization revealed better dispersion of M-CNTs in the polyurethane, which is attributed to the improved interaction between the M-CNTs and polyurethane. Loading of the metal nanoparticle coated carbon nanotubes resulted in the significant improvement on the mechanical properties such as tensile strength of the PU composites in comparison to the pristine carbon nanotubes (P-CNTs). Dynamic mechanical analysis showed that the glass transition temperature (Tg) of the polyurethane increases slightly with increasing loading of both pristine and metal nanoparticle functionalized carbon nanotubes. The metal nanoparticles decorated carbon nanotubes also showed significant improvement in the thermal and electrical conductivity of the PU/M-CNTs nanocomposites. Shape memory studies of the PU/M-CNTs nanocomposites exhibit remarkable recoverability of its shape at lower applied dc voltages.