氧化石墨烯/聚乙烯醇复合材料的纳米压痕实验及力学性能

为了研究氧化石墨烯(GO)对聚合物基复合材料力学性能的影响,通过溶液混合法制备了GO/聚乙烯醇(PVA)复合材料。然后,采用XRD、TEM、FTIR、DSC和纳米压痕实验等研究了GO/PVA复合材料的结构、界面结合性能、力学性能、蠕变行为和吸水膨胀率。结果表明:GO可以均匀分散在PVA基体中,二者之间主要通过氢键作用结合,具有较高的界面结合力;与纯PVA相比,1wt% GO/PVA复合材料的硬度和有效弹性模量分别提高了28.9%和23.3%,压入蠕变深度下降了19.8%;GO/PVA复合材料具有较低的无限剪切模量与瞬时剪切模量比,表明GO提高了PVA的蠕变抗力;GO的添加同时增加了GO/PVA复合材料的阻水性并降低了膨胀系数。吸湿纳米压痕实验结果表明:纯PVA的力学性能会随吸湿时间延长而下降,而GO/PVA复合材料吸湿72h后的力学性能基本保持不变。所得结论为石墨烯增强聚合物基复合材料的研究提供了理论指导。      

纳米SiO_2/环氧树脂复合材料的制备方法与性能关系

采用超声分散、机械剪切搅拌和纳米SiO_2粒子表面处理等多种分散工艺,制备了纳米SiO_2/环氧树脂复合材料。采用SEM、电子拉力机、粘弹谱仪和脉冲声管测试系统分别研究了纳米SiO_2/环氧树脂复合材料的微观结构、拉伸性能、动态力学性能和水声性能。结果表明,超声波分散法以及预处理法能够将纳米SiO_2粒子均匀分散在环氧树脂基体中,并且SiO_2粒子呈纳米尺度分布在环氧基体中。相对纯环氧树脂材料,纳米SiO_2/环氧树脂复合材料的拉伸强度提高了5%—30%,伸长率提高了2%—14%;储能模量随纳米SiO_2粒子的加入与均匀分散而提高,损耗因子则略有下降;吸声系数相对纯环氧树脂材料提高了6—10倍;而且纳米SiO_2/环氧树脂复合材料的常规力学性能、动态力学性能以及水声性能受纳米粒子的分散效果影响明显,分散越均匀,变化越大。     

生物基六方氮化硼分散液在环氧复合材料中的应用

六方氮化硼(hBN)是具有良好机械性能、高导热性和优异润滑性能的新型二维纳米材料,它具有增强聚合物纳米复合材料的潜力。将hBN均匀分散于生物基环氧单体糠醇缩水甘油醚(FgE)中,采用TEM和AFM对其在FgE中的分散状态进行了表征,成功制备了低于10层的hBN纳米片分散液。将FgE-hBN分散液作为环氧树脂的活性稀释剂,在不使用任何有机溶剂作稀释剂的情况下,制备了FgE-hBN/环氧复合材料。研究结果证明,在FgE-hBN的存在下,环氧树脂的疏水性、耐热性能、机械性能以及耐摩擦性能均得到极大提升。环氧树脂性能的提高主要归因于良好分散的hBN纳米片自身具有的高疏水性、强导热性、强机械性及高润滑等优异性能。     

基于纳米压痕技术的碳纤维/环氧树脂复合材料各组分原位力学性能测试

基于纳米压痕技术对碳纤维/环氧树脂复合材料各组分的原位硬度、 弹性模量和蠕变性能进行了测试, 实验得到了基体、 纤维和微小厚度界面层的力学性能。结果表明, 从环氧树脂基体到碳纤维过渡过程中, 硬度和弹性模量有明显的梯度变化, 并且纤维和树脂基体的原位弹性模量平均值与其非原位性能有一定的变化, 实验得到纤维的原位弹性模量有所下降, 环氧树脂的弹性模量有所增加。试件制备过程中的机械研磨对其表面产生的残余应力和复合后两种材料的相互影响是组分材料原位性能变化的主要原因。各组分的蠕变性能呈现出明显的差异。     

环氧树脂改性水性聚氨酯胶粘剂的性能研究

通过丙酮法合成了一系列在软、硬段均含有离子基的水性聚氨酯分散液,采用共混法重点研究了环氧值,环氧树脂加入量以及R值(NCO/OH比)和离子基含量对水性聚氨酯乳液性能和胶粘剂粘接性能的影响。结果表明:选择E-44具有最佳的工艺和性能平衡,当E-44含量为3(wt%,质量分数),R值为1.3和离子基含量为1.15(wt%,质量分数)时所合成粘合剂的乳液稳定性,耐热性能和最佳的粘合性能。     

纳米SiO2-氧化石墨烯/环氧涂层的制备及其防腐蚀性能

采用改进Hummers法制备了氧化石墨烯（GO）,并将GO与经硅烷偶联剂γ-氨丙基三乙氧基硅烷（KH550）改性的纳米SiO₂进行复合,制备出纳米SiO₂-GO。通过FTIR、XRD、SEM、TEM等分析手段对SiO₂-GO进行表征。采用机械搅拌与超声分散的方法将SiO₂-GO添加到环氧树脂（EP）中。对添加不同质量分数纳米SiO₂、GO和纳米SiO₂-GO的EP基复合材料涂层的物理性能和电化学性能进行测试。结果表明,与纯EP涂层相比,SiO₂/EP、GO/EP和纳米SiO₂-GO/EP复合材料涂层的硬度、附着力和耐腐蚀性能得到显著增强,其中加入2wt%纳米SiO₂-GO/EP复合材料涂层硬度达到5 H,附着力等级达到1级,浸泡24 h后涂层保护效率为99.33%。15天浸泡试验结果表明,添加1.5wt%纳米SiO₂-GO/EP复合材料涂层的硬度达到5 H,附着力达到1级,涂层保护效率仍能达到97.12%。     

氧化石墨烯纳米片/环氧树脂复合材料的制备与性能

氧化石墨烯(GO)是石墨烯重要的衍生物之一,通过氧化和超声波分散制备了GO纳米片/环氧树脂复合材料。采用XRD、拉曼光谱、FTIR和TEM表征了GO纳米片的结构与形貌,研究了GO纳米片用量对GO纳米片/环氧树脂复合材料热稳定性、力学性能及介电性能的影响。结果表明:GO纳米片的加入提高了GO纳米片/环氧树脂复合材料失热稳定性;随着GO纳米片填充量的增加,GO纳米片/环氧树脂复合材料的冲击强度和抗弯性能先提高后降低,其介电常数和介电损耗则先减小后增加。GO纳米片填充量为0.3wt%的GO纳米片/环氧树脂复合材料的失重5%时的热分解温度由纯环氧树脂的400.2℃提高到424.5℃,而冲击强度和弯曲强度分别在GO纳米片填充量为0.2wt%和0.3wt%时达到最大,冲击强度由纯环氧树脂的10.5kJ/m2提高到19.7kJ/m2,弯曲强度由80.5 MPa提高到104.0 MPa。     

硅橡胶压磁复合材料力学性能纳米压痕实验研究

通过纳米压痕测试技术对非晶Fe73.5Cu1Nb3Si13.5B9/硅橡胶压磁复合材料薄膜的力学性能进行了研究,讨论了加载速率、保载时间、峰值载荷等试验参数对模量和硬度测试结果的影响.进一步分析了纳米压痕实验表征非晶Fe73.5Cu1Nb3Si13.5B9/硅橡胶压磁复合材料薄膜蠕变行为的可行性,通过合理确定压痕蠕变实验参数,获得该材料的蠕变应力指数.结果表明:相对峰值载荷,加载速率对测试结果影响更为显著,而保载时间对硬度和模量测试结果几乎没有影响.     

PLA/HNTs纳米复合材料的制备、性能及其发泡行为

采用熔融共混炼法制备交联改性聚乳酸(PLA)/埃洛石(HNTs)纳米复合材料,利用热重分析、差示扫描量热分析、偏光显微镜和流变仪对其热学性能、结晶、流变行为进行了研究,并采用超临界CO2流体技术进行微孔发泡,利用扫描电镜对泡孔形态进行了表征。结果表明:随着HNTs含量的增加,PLA/HNTs复合体系在高温下的热稳定性下降,结晶度由37.4%下降为28.0%,但异相成核效果明显,结晶速率提高,结晶时间由2h缩短为10min。同时,加入HNTs后,PLA/HNTs的熔体粘度显著增加,但随着HNTs含量的增多,PLA/HNTs纳米复合材料粘度增加的趋势逐渐趋缓。当HNTs含量为0.5wt%时,体系粘度达到最大值且发泡效果最佳,泡孔平均直径为21.23μm,泡孔密度达到1.08×109个/cm3。     

改性纳米TiO2/环氧-聚氨酯三元复合材料的制备及性能研究

油酸改性的纳米TiO_2与一定量二苯基甲烷二异氰酸酯(MDI)和环氧树脂(E51)等充分反应,得到的乳液通过红外光谱(FT-IR)、扫描电镜(SEM)等手段进行表征和分析,证实了改性纳米TiO_2成功接枝到环氧-聚氨酯共聚物分子链上形成了稳定的三元复合材料。结果表明:三元复合材料的稳定性能好,涂膜的耐水性能和力学性能强,当TiO_2质量含量为0.8%时,复合涂膜的铅笔硬度最高达3H,拉伸强度最高达12.3MPa,涂膜的抗紫外、抗老化性能亦有明显提高。     

Evaluation of surface properties of epoxy–nanodiamonds composites

Epoxy–matrix reinforced with nanodiamond (ND) particles, with ND content up to 5 wt%, were synthesized. Characterization of NDs by field emission scanning electron microscopy (FE-SEM) and Raman spectroscopy was conducted, while composites were characterized through contact angle, nanoindentation, nanoscratch and scanning probe microscopy. The assessed properties evaluated were hardness, elastic modulus, contact angle, deformation mechanisms, creep deformation, coefficient of friction and adhesion, namely. Results showed that even small additions of ND lead to significant enhancement in the hardness and elastic modulus of epoxy matrix, while properties of composites present a switch in behavior after passing a concentration threshold; this threshold was identified and discussed.     

Single-walled carbon nanotube incorporated novel three phase carbon/epoxy composite with enhanced properties

In the present work, single-walled carbon nanotubes were dispersed within the matrix of carbon fabric reinforced epoxy composites in order to develop novel three phase carbon/epoxy/single-walled carbon nanotube composites. A combination of ultrasonication and high speed mechanical stirring at 2000 rpm was used to uniformly disperse carbon nanotubes in the epoxy resin. The state of carbon nanotube dispersion in the epoxy resin and within the nanocomposites was characterized with the help of optical microscopy and atomic force microscopy. Pure carbon/epoxy and three phase composites were characterized for mechanical properties (tensile and compressive) as well as for thermal and electrical conductivity. Fracture surfaces of composites after tensile test were also studied in order to investigate the effect of dispersed carbon nanotubes on the failure behavior of composites. Dispersion of only 0.1 wt% nanotubes in the matrix led to improvements of 95% in Young's modulus, 31% in tensile strength, 76% in compressive modulus and 41% in compressive strength of carbon/epoxy composites. In addition to that, electrical and thermal conductivity also improved significantly with addition of carbon nanotubes.     

埃洛石纳米管/聚乙烯醇-淀粉复合膜的结构与性能

采用溶液流延法制备了埃洛石纳米管(HNTs)/聚乙烯醇(PVA)-淀粉复合膜,并利用SEM、XRD、DMA、TGA等分析测试手段研究了该复合膜的结构与性能。结果表明:随着HNTs含量增加,HNTs/PVA-淀粉复合膜的力学性能、热稳定性、耐水性能和紫外屏蔽性能均有提高。当HNTs与PVA-淀粉质量比为10%时,力学性能达到最佳,拉伸强度提高了22%。扫描电镜分析表明:HNTs能够以纳米尺度均匀分散于HNTs/PVA-淀粉复合膜中,且以单管状分布,与PVA-淀粉基体界面结合较好。动态力学性能分析表明:HNTs的加入对HNTs/PVA-淀粉复合膜的玻璃化转变温度影响不大,复合膜的储能模量升高,力学损耗下降。透光率测试结果表明:HNTs对HNTs/PVA-淀粉复合膜的透明性影响不大,而在紫外光区域(200~400nm),透光率随HNTs量的增加而下降。     

Interlaminar properties of carbon fiber composites with halloysite nanotube-toughened epoxy matrix

Halloysite nanotubes (HNTs), which are geometrically similar to multi-walled carbon nanotubes, can improve the impact strength of epoxy substantially, according to our previous work [1]. Using a HNT-toughened epoxy as the matrix, a set of hybrid composites was prepared with carbon fiber-woven fabrics. The interlaminar properties of the composites were investigated by a short-beam shear test, a double-cantilever-beam test and an end-notched flexure test. The results showed that the addition of HNTs to the composites improved the interlaminar shear strength and the fracture resistance under Mode I and Mode II loadings greatly. The morphological study of the hybrid composites revealed that HNTs were non-uniformly dispersed in the epoxy matrix, forming a unique microstructure with a large number of HNT-rich composite particles enveloped by a continuous epoxy-rich phase. A study of the fracture mechanism uncovered the important role of this special morphology during the fracturing of the hybrid composites.     

Introducing cellulose nanocrystals in sheet molding compounds (SMC)

The mechanical properties of short glass fiber/epoxy composites containing cellulose nanocrystals (CNC) made using sheet molding compound (SMC) manufacturing method as well as the rheological and thermomechanical properties of the CNC-epoxy composites were investigated as a function of the CNC content. CNC up to 1.4 wt% were dispersed in the epoxy to produce the resin for SMC production. The addition of CNC in the resin increased its viscosity and slightly reduced the heat of reaction during the polymerization without altering the curing time and temperature and the effective pot life of the resin. The incorporation of 0.9 wt% CNC in the SMC composite resulted in increases in elastic modulus and tensile strength by ∼25% and ∼30% and in flexural modulus and strength by ∼44% and ∼33% respectively. Concentrations of CNC up to 0.9 wt% in the SMC composite did not alter the impact energy.     

石墨烯-多壁碳纳米管协同增强环氧树脂复合材料的低温力学性能

为了提高环氧树脂的低温力学性能,采用石墨烯与多壁碳纳米管(MWCNTs)协同改性环氧树脂,系统研究了石墨烯-MWCNTs/环氧树脂复合材料的室温(RT)和低温(77K)力学性能。结果表明:当石墨烯的质量分数为0.1wt%,MWCNTs的质量分数为0.5wt%时,纳米填料的加入可同时改善环氧树脂的低温拉伸强度、弹性模量和冲击强度;在此最佳含量下,石墨烯-MWCNTs/环氧树脂复合材料在RT和77K时的拉伸强度皆达到最大值,比纯环氧树脂的拉伸强度分别提高了11.04%和43.78%。石墨烯和MWCNTs能协同提高环氧树脂的低温力学性能。     

石墨烯/环氧树脂复合材料的制备与力学性能

通过对氧化石墨热膨胀还原并用超声分散制备了石墨烯,并对所得产物进行分析表征。用超声分散和模具浇注成型法制备了石墨烯/环氧树脂纳米复合材料。研究了石墨烯含量对石墨烯/环氧树脂复合材料力学性能和断面形貌的影响,分析了石墨烯对环氧树脂的增强机理。结果表明,随着石墨烯含量的增加,石墨烯/环氧树脂复合材料的拉伸强度及模量先增加后减小;当石墨烯的质量分数为0.1%时,复合材料的拉伸强度达到最大值60.9MPa,比纯环氧树脂提高了16.88%;当石墨烯的质量分数为0.5%时,复合材料的拉伸模量达到最大值2833.3MPa,比纯环氧树脂提高了48.29%。     

Enhanced thermal and mechanical properties of carbon nanotube composites through the use of functionalized CNT-reactive polymer linkages and three-roll milling

We report enhanced thermal and mechanical properties of carbon nanotube (CNT) composites achieved through the use of functionalized CNTs-reactive polymer linkages and three-roll milling. CNTs were functionalized with carboxyl groups and dispersed in a polymer containing an epoxide group resulting in a chemical reaction. To maximize CNT dispersion for practical usage, entangled CNTs are separated and then evenly dispersed within the polymer matrix using three horizontally positioned rotating rolls that apply a strong shear force to the composite. Consequently, accompanying with thermal stability, elastic modulus and storage modulus of such functionalized CNT/polymer composites were increased by 100% and 500% that of the untreated epoxy polymer.