短纤维增强橡胶复合材料研究进展

综述了短纤维增强橡胶复合材料制备过程中短纤维的预处理、短纤维的混合、分散、取向方法及影响因素，并介绍短纤维增强橡胶复合材料的新进展。     

短纤维增强橡胶复合材料研究进展

综述了短纤维增强橡胶复合材料制备过程中短纤维的预处理、短纤维的混合、分散、取向方法及影响因素 ,并介绍短纤维增强橡胶复合材料的新进展     

氧化铝短纤维增强铝合金复合材料界面的研究

本文在浸渗法制备复合材料的基础上,研究了氧化铝短纤维增强铝合金复合材料的界面.研究结果表明,在复合材料中,纤维与基体之间存在明显的界面层,合金元素通过适当的化学反应可改善浸润状况,有利于纤维与基体的结合.试样断口分析还表明,复合材料的界面结合状况良好,可传递足够的载荷到纤维上,发挥其增强作用.     

芳纶短纤维增强天然橡胶耐磨材料的研究

利用芳纶短纤维增强天然橡胶耐磨材料,研究了纤维含量、长度和纤维粘合处理、混炼工艺等因素对短纤维复合材料性能的影响及芳纶浆粕和短纤维增强复合材料的热老化性能。实验发现,在开炼机上将芳纶短纤维直接加入母校炼校的混炼工艺和芳纶长复丝活化、浸ＲＦＬ后再短切的纤维处理方法可以实现纤维的较好分散和粘合。性能测试结果表明,芳纶短纤维使复合材料具有性能各向异性和更大的拉伸模量、硬度,更好的热老化性、耐溶剂性和纤维     

Al2O3f+Cf/ZL109铝基混杂复合材料的制备及热处理

利用预制体挤压浸渗法制备了Al2O3f Cf/ZL109短纤维混杂金属基复合材料，并研究了固溶和时效时间对该混杂复合材料力学性能的影响。结果表明：复合材料中两种纤维混杂分布均匀，经热处理后，复合材料基体组织细化，较佳的热处理工艺参数为510℃固溶4h，170℃时效4-8h。复合材料断裂主要为大角度的纤维脱粘所致。     

短纤维增强金属基复合材料的细观塑性变形与宏观性能

本文研究单向短纤维增强金属基复合材料的细现弹塑性变形和宏观弹塑性响应。假设纤维是弹性体,基体是弹性粘塑性体。利用有限元法分析了复合材料可周期性重复的单胞的细观弹塑性应力场;利用体积平均的均匀化方法研究了复合材料的弹塑性应力-应变关系。本工作着重分析复合材料中纤维与纤维、纤维与周围基体的相互作用机理。     

短纤维/ABS树脂复合材料导电导热性能研究

以沥青基短纤维为填料、ABS树脂为基体,采用热压成型工艺制备了短纤维/ABS树脂复合材料,研究了短纤维在复合材料中的分散形貌及其含量和长度对复合材料导电、导热和抗冲击性能的影响。研究结果表明:短纤维在复合材料中分散较为均匀,可以形成较好的导电和导热网络。复合材料沿垂直热压方向的室温电阻率和热导率随短纤维含量和长度的增加而分别呈降低和升高趋势,其电阻率具有明显的"渗逾"现象,添加0.5mm长的纤维粉的复合材料的导电突变用量约为13wt.%,其电阻率为0.6Ω·m,而填充长度为3mm和6mm短纤维的复合材料的渗逾值约为11wt.%,相应电阻率降低至9.0×10-3Ω·m和1.0×10-3Ω·m。当3mm长短纤维含量为29wt.%时,复合材料的室温热导率为23.3W/m·K,较纯ABS树脂提高了136倍。     

Al_2O_3短纤维/M124F复合材料的凝固组织

采用挤压铸造法制备了Al2O3短纤维增强M124F铝合金复合材料,并研究了其拉伸强度、基体凝固组织和界面。结果表明:用挤压铸造法制备的复合材料组织致密,纤维分布均匀,抗拉强度与M124F相比明显提高;基体组织的α-Al枝晶和Si相明显细化。分析表明,纤维的加入具有双重增强作用:高强度陶瓷纤维的介入增强了基体材料的力学性能;在凝固过程中,Al2O3短纤维阻碍了α-Al枝晶的生长,同时可作为Si相非自发形核的衬底,细化了基体组织,提高了复合材料的力学性能。纤维与基体间未发现界面生成物MgAl2O4。     

短纤维对基体微裂纹扩展的阻滞效应分析

本文用细观力学方法分析短纤维对基体微裂纹扩展的阻滞效应。考虑了单向和随机各向两类短纤维增强复合材料,用应力强度因子和应变能密度因子的变化来表征纤维阻滞裂纹扩展的效应。本文对三种短纤维复合材料作出了具体计算。     

非均相固化体系对复合材料树脂微观力学均匀性的影响

采用热熔法制备预浸料涉及熔融树脂对纤维层的渗透,对于固化体系为非均相的环氧树脂基体,制备大厚度预浸料可能会受到固化剂分布不均的影响。利用纳米力学方法分别研究采用小厚度玻璃纤维预浸料制备的复合材料和通过树脂真空吸注工艺制备的玻璃纤维复合材料的内部树脂的微观力学均匀性。结果表明:由小厚度预浸料制备的复合材料,其内部树脂各区域具有较好的微观力学均匀性,各区域树脂的纳米硬度和耐磨损性基本相同,各铺层中心和边缘接近;通过树脂真空吸注工艺制备的复合材料则表现出明显的层状分布,固化剂和促进剂颗粒在纤维层外部富集,纤维层外层的树脂具有较高的纳米硬度和耐磨损性,而在纤维层内0.4mm深后的树脂纳米硬度下降,耐磨损性下降,纤维层内部的树脂纳米硬度很低。     

Improved multi-orientation dispersion of short carbon fibers in aluminum matrix composites prepared with square crucible by mechanical stirring

In order to improve the strength of short carbon fibers reinforced aluminum matrix(Csf/Al) composite, the dispersion of short carbon fibers with multi-orientation was controlled with a square crucible by mechanical stirring. The three-dimensional flow field models of liquid aluminum melt in the square/round crucibles were established and calculated, and the results were compared. The calculated results show that turbulent flow could be induced both in the square and round crucible, while the non-axisymmetric structure of the square crucible results in higher turbulent kinetic energy in the melt. Therefore, the uniformity and multi-orientation dispersion of the short fibers can be improved by the intensive turbulent flow in the square crucible, which will be increased by increasing the rotational velocity. The distribution of the short carbon fibers in the aluminum matrix prepared under different rotation velocities in square crucible was experimentally investigated. With the increase of stirring velocity, the multi-orientation dispersion of the short fibers in the composites increased gradually. The experimental results are consistent with the calculation results. The tensile testing results show that the strength of the Csf/Al composite can reach 172 MPa when the rotational velocity is 1000 rpm, and it is 48.3% higher than that prepared by the round crucible under the same conditions, which results from the improved multi-orientation dispersion of short carbon fibers in aluminum matrix.     

尼龙66电纺纳米纤维膜的纤维分散形态和结晶性能

采用高压静电纺丝方法,制备了尼龙66电纺纤维膜,纤维的直径为纳米级。运用场发射扫描电镜(EFSEM)观察了纺丝液的浓度、电压、固化距离等参数对尼龙66电纺纤维膜的纤维分散形态和直径大小的影响,运用XRD分析了纺丝液浓度和电压对电纺纤维结晶度的影响。结果表明,纺丝液浓度对纤维分散形态有决定性作用,尼龙66电纺纤维膜结晶度比未纺丝的尼龙66的结晶度要低得多,并且电压对结晶度影响很大,电压增加使结晶度降低,电纺纤维膜的晶体结构趋于无定型。     

Preparation of poly (vinyl alcohol) fibers strengthened using multiwalled carbon nanotubes functionalized with tea polyphenols

Poly (vinyl alcohol) (PVA) fibers were strengthened using multiwalled carbon nanotubes (MWCNTs) functionalized using a green modifier tea polyphenols (TP). MWCNTs were first modified using TP to increase their dispersity in dimethyl sulfoxide (DMSO)/water solution, and then PVA was added to the dispersion to form new dispersion of PVA/MWCNTs/TP/DMSO/water. The homogeneous dispersion was extruded through a spinning hole into cold methanol to form continuous fibers using gel-spinning process followed by a hot-drawing. The tensile strength of the well-oriented PVA/MWCNTs composite fibers containing merely 0.6 wt% of MWCNTs was surprisingly more than 2.6 times that of pure PVA fiber. Structure characterization showed that well-dispersed MWCNTs were caused by the interfacial interactions between PVA matrix and MWCNTs through the bridge effect of TP.     

短碳纤维的分散性对CFRC力学性能的影响

碳纤维增强水泥基复合材料(CFRC)是一种新型建筑智能材料,碳纤维在水泥基体中的分散性直接影响着它的力学性能.借助超声波和甲基纤维素(MC)分散剂,实现了短碳纤维在水泥基体中的均匀分散,对所制备的CFRC复合材料的断口形貌作了SEM观察;测试了试件的抗压强度、抗拉强度和抗折强度.结果发现,碳纤维均匀分散时,复合材料的抗压强度提高19%,抗拉强度比不加碳纤维时提高2.2倍,弹性模量提高1.4倍.此外,复合材料的抗弯强度、抗折强度均高于未均匀分散时的强度.     

Multi-walled carbon nanotubes and poly(lactic acid) nanocomposite fibrous membranes prepared by solution blow spinning

Nanocomposite fibers based on multi-walled carbon nanotubes (MWCNT) and poly(lactic acid) (PLA) were prepared by solution blow spinning (SBS). Fiber morphology was characterized by scanning electron microscopy (SEM) and optical microscopy (OM). Electrical, thermal, surface and crystalline properties of the spun fibers were evaluated, respectively, by conductivity measurements (4-point probe), thermogravimetric analyses (TGA), differential scanning calorimetry (DSC), contact angle and X-ray diffraction (XRD). OM analysis of the spun mats showed a poor dispersion of MWCNT in the matrix, however dispersion in solution was increased during spinning where droplets of PLA in solution loaded with MWCNT were pulled by the pressure drop at the nozzle, producing PLA fibers filled with MWCNT. Good electrical conductivity and hydrophobicity can be achieved at low carbon nanotube contents. When only 1 wt% MWCNT was added to low-crystalline PLA, surface conductivity of the composites increased from 5 x 10(-8) to 0.46 S/cm. Addition of MWCNT can slightly influence the degree of crystallinity of PLA fibers as studied by XRD and DSC. Thermogravimetric analyses showed that MWCNT loading can decrease the onset degradation temperature of the composites which was attributed to the catalytic effect of metallic residues in MWCNT. Moreover, it was demonstrated that hydrophilicity slightly increased with an increase in MWCNT content. These results show that solution blow spinning can also be used to produce nanocomposite fibers with many potential applications such as in sensors and biosensors.     

Ultrasonic Determination of Stiffness Properties of an Orthotropic Viscoelastic Material

Abstract

Ultrasonic velocity measurements were used to populate the real portion of the stiffness matrix of an orthotropic viscoelastic material, as a function of frequency. The orthotropy originated from short cellulose reinforcing fibers cast into the polypropylene matrix. The results were consistent with a Zener relaxation model for the material, with a time constant of the order of a few microseconds. It was found that the shape of the dispersion curve varied markedly with orientation: The frequency dependence of the phase velocity was at a minimum along the primary axis of the reinforcing fibers; the fibers were shown to inhibit viscoelastic behavior in this direction. The attenuation coefficient was measured along one primary axis of the material, and found to be consistent with the dispersion curves and localized form of the Kramers-Kronig relationships linking the real and imaginary components of the stiffness matrix.     

Ultrasonic Determination of Stiffness Properties of an Orthotropic Viscoelastic Material

Ultrasonic velocity measurements were used to populate the real portion of the stiffness matrix of an orthotropic viscoelastic material, as a function of frequency. The orthotropy originated from short cellulose reinforcing fibers cast into the polypropylene matrix. The results were consistent with a Zener relaxation model for the material, with a time constant of the order of a few microseconds. It was found that the shape of the dispersion curve varied markedly with orientation: The frequency dependence of the phase velocity was at a minimum along the primary axis of the reinforcing fibers; the fibers were shown to inhibit viscoelastic behavior in this direction. The attenuation coefficient was measured along one primary axis of the material, and found to be consistent with the dispersion curves and localized form of the Kramers-Kronig relationships linking the real and imaginary components of the stiffness matrix.     

短切炭纤维的CVI处理及其在CFRC中的分散性

采用CVI法对短炭纤维进行表面处理, 借助超声波对其进行预分散, 用新型分散剂羟乙基纤维素(HEC)和超细粉硅灰对其进行分散, 并研究了其在水泥基体中的分散性; 在SEM电镜下观察了短炭纤维增强水泥基复合材料(CFRC)的断口形貌, 用炭纤维质量变动系数定量评价了短炭纤维在CFRC中的分散性。结果表明, 采用CVI预处理和超声波预分散, 在分散剂HEC和硅灰不同掺量下, 炭纤维的分散性均得到显著改善。炭纤维的分散性随HEC掺量的增加而提高, 当HEC掺量为水泥质量的0.6%、 硅灰掺量为水泥质量的10%时, 两种分散剂的协同作用使炭纤维质量变动系数最小, 此时炭纤维在水泥基体中的分散性最理想。      

静电纺丝法制备金纳米粒子/PVP复合纳米纤维

采用水合肼还原一定浓度氯金酸溶液的方法,在聚乙烯吡咯烷酮(PVP)作保护剂的乙醇/水溶液中,成功制备出粒度较小,且高度分散的金溶胶,紫外吸收光谱证实了溶液中金纳米粒子的存在.采用静电纺丝技术制备了AuNs/PVP复合纳米纤维.采用扫描电镜(SEM)和X射线衍射(XRD)等分析手段对纤维的表面形貌等进行了表征.由扫描电镜...     

水环境对聚酰亚胺纤维分散及纸基材料性能的影响

通过改变水环境的电导率、pH值、温度及纤维浓度并以正交试验加以优化,对聚酰亚胺短切纤维悬浮液的分散效果进行研究。采用纤维沉降度、吸光度、Zeta电位表征了不同水环境条件下聚酰亚胺纤维悬浮液的分散性能,确定了实验条件下最佳水环境的相关参数,优选出最适宜的纤维浓度,并对最佳水环境条件下分散后的纤维所成型的聚酰亚胺纤维纸基材料性能进行了探讨。结果表明,在实验条件下,当水体的pH值为6.0,水温为40℃,纤维浓度为4‰且水溶液电导率较低时,聚酰亚胺短切纤维的分散性能更好,成纸孔径分布更加均匀,在此分散工艺下成形的纸基材料的拉伸强度指数为35.9 N/mg,撕裂指数为40.1 mN·m 2/g。