碳纤维增强聚苯硫醚复合材料感应焊接研究

以碳纤维/聚苯硫醚(CF/PPS)层合板为研究对象,采用DOE方法优化设计感应焊接实验方案,研究焊接接头性能,并对其截面和断口形貌进行观察,揭示焊接工艺参数对焊接接头性能的影响机制。结果表明,通过DOE方法获得最佳焊接工艺参数(功率2.0kW、压力1.5MPa、时间3.0min),焊接接头最大单搭接剪切强度为13.87MPa,与实验验证结果(13.25MPa)相近;接头剪切强度随着焊接工艺参数值的增加,均呈现先增大后减小的变化趋势;在最佳焊接工艺参数下,焊接接头结合紧密,失效形式为不锈钢网的撕裂与纤维的断裂拔出,呈现出高剪切强度;而在过低或过高焊接工艺参数下,界面脱黏为主要失效形式,剪切强度较低。     

碳纤维增强聚苯硫醚复合材料结晶结构与性能调控

使用碳纤维斜纹布与聚苯硫醚(PPS)薄膜通过热压成型制备了碳纤维增强PPS (PPS/CF)复合材料层压板,通过在保温保压过程中设置不同的等温结晶温度,对复合材料中PPS结晶结构进行调控,系统讨论了不同等温结晶温度下,PPS结晶度及晶粒尺寸对PPS/CF复合材料力学性能的影响。使用X射线衍射仪观察了复合材料中PPS的晶体结构,通过场发射扫描电子显微镜观察了复合材料的微观形貌,并利用动态机械分析测试探究了复合材料的黏弹性与PPS晶体结构之间的关系。结果表明,当等温结晶温度为230℃时,复合材料中PPS在保持较小晶粒尺寸的同时结晶度高达46.58%,此时复合材料具有良好的强度、刚性和界面粘结强度,其弯曲强度、弯曲弹性模量和层间剪切强度分别达到709 MPa,81.9 GPa和23.8 MPa。     

酚酞型聚芳醚酮改性PPS/CF复合材料的制备与性能研究

采用不同浓度的酚酞型聚芳醚酮（PEK-C）溶液对碳纤维（CF）进行表面处理,并制备了碳纤维增强聚苯硫醚（PPS/CF）复合材料。结果表明：与去浆后CF(CF-A)相比,浓度0.50%的PEK-C溶液处理的CF表面O/C比提升约49.2%,且C—O键和C=O键占比明显提升。说明PEK-C溶液处理可以有效增加CF表面含氧官能团的数量,且在该条件下复合材料的界面性能和弯曲性能大幅提升,相较于未经PEK-C改性的PPS/CF复合材料,0.50%的PEK-C溶液改性后的PPS/CF复合材料层间剪切强度由23.81 MPa提高至38.45 MPa,弯曲强度由709 MPa提高至839 MPa。     

表面处理对碳纤维/聚苯硫醚复合材料性能的影响

以碳纤维(CF)平纹织物、聚苯硫醚(PPS)纤维为原材料,通过混杂铺丝及热压的方法制备出CF/PPS热塑性复合材料。研究了不同表面处理方法对CF表面官能团、碳(C)与氧(O)元素含量比、单丝拔出强度及复合材料两相浸润性、界面性能、力学性能等的影响。结果表明:丙酮处理可以有效去除CF的上浆剂,利于PPS熔体在CF之间的均匀分散与浸渍,在一定程度上提升了CF/PPS复合材料的力学性能;硝酸溶液处理可以增加CF平纹织物表面的O/C摩尔比,且CF表面轴向产生缺陷和沟壑;CF与PPS之间的界面剪切强度随硝酸处理时间的增加而明显增加,但CF/PPS复合材料的力学性能呈现先增加后降低的趋势;通过表面处理改善CF与PPS之间的浸润性以及界面相互作用力,可以提升CF/PPS复合材料的力学性能。     

碳纤维增强热塑性复合材料感应焊接的温度控制及接头强度

随着热塑性复合材料在航空领域的用量日益增加,如何解决结构复杂热塑性航空部件的连接问题引起了研究者的广泛关注。利用其可二次成型的特点可采用焊接,感应焊接是其中一种快捷、可靠的连接方式。感应焊接工艺过程稳定,可实现连续化焊接,是一种人为因素介入较少、小(焊接装置小)、快(焊接速度快)、灵活的焊接技术,也被视为热塑性复合材料连接技术未来最重要的发展方向。本文采用热电偶测温研究了连续碳纤维增强聚苯硫醚(CF/PPS)焊接试样厚度方向上温度分布及温度随时间的变化规律,确定了不同功率下焊接试样可焊的最长时间。采用定点焊接的方式研究了焊接功率及时间对单搭接剪切强度的影响,并探索了不同植入层用于CF/PPS热塑性复合材料感应焊接的可行性。     

聚合物基复合材料电阻焊接技术研究进展

聚合物基复合材料以其优异的特性在各领域广泛应用,聚合物基复合材料的熔融连接技术一直是研究的重点。本文系统地综述了影响电阻焊接接头质量的加热元件、焊接压力和输入功率等工艺参数和焊接过程的温度分布情况,讨论了热固性聚合物基复合材料电阻焊接的实现及电阻焊接有限元模型的建立,展望了聚合物基复合材料电阻焊接技术未来的研究方向。     

静电粉末流化法碳纤维/聚苯硫醚预浸料的制备及性能表征

利用静电粉末浸渍工艺探索碳纤维增强聚苯硫醚(CF/PPS)预浸料的制备方法,通过差示扫描量热法(DSC)测试和热失重分析探讨了成型温度对CF/PPS预浸料的综合热性能的影响;表征了成型后CF/PPS复合材料的力学性能,以及PPS对碳纤维的浸润情况。结果显示,升高浸渍温度,可降低树脂黏度,PPS对碳纤维呈现良好的浸润效果,在升温至320℃时,PPS链段具有较高的活性和结晶能力,在长时间处于330℃高温下,PPS链段易发生支化交联影响了复合材料性能,CF/PPS预浸料热分解温度在520℃左右,随浸渍温度的提高,复合材料力学性能呈现先增加后降低的趋势,拉伸强度和弯曲强度最高可达到877.3 MPa和737 MPa,在扫描电子显微镜(SEM)下显示PPS树脂充分浸润了纤维丝束,浸渍效果良好。     

连续CF增强PEEK复合材料层压板的制备工艺

采用熔融浸渍法制备了连续碳纤维(CF)增强聚醚醚酮(PEEK)复合材料预浸带,并层压成型制备复合材料层压板。研究了成型温度、成型压力、成型时间、纤维含量等因素对复合材料层压板力学性能的影响。结果表明,在成型温度为370℃、成型压力为12 MPa、成型时间为70 min、纤维含量为61%的工艺条件下,连续CF增强PEEK复合材料层压板的力学性能达到最优值,弯曲强度和弯曲弹性模量分别达到(1 750.76±49.13)MPa和(107.54±6.35)GPa,层间剪切强度达到(100.04±6.88)MPa,缺口冲击强度为(84.44±1.54)k J/m2。随着冷却速率的增大,复合材料层压板的弯曲性能和层间剪切强度下降,而缺口冲击强度提高。SEM分析表明,复合材料层压板的界面粘结良好。     

无机颗粒/碳纤维共增强聚酰胺6复合材料的制备与力学性能研究

采用熔融挤出法制备出无机颗粒(IP)增强聚酰胺6(PA6)复合材料,使用叠层模压法制备了IP/碳纤维(CF)共增强PA6复合材料(PA6/IP/CF)。利用场发射扫描电子显微镜、万能试验机等研究了IP的形貌和含量对复合材料性能的影响。结果表明,当滑石粉(TALC)的添加量达到10%(质量分数,下同)时,PA6/CF/TALC复合材料的各项力学性能达到最大值,弯曲强度为374.6 MPa、剪切强度为58.7 MPa、冲击强度为76.9 kJ/m~2;当玻璃微珠(GB)的添加量达到15%时,PA6/CF/GB复合材料的各项力学性能达到最大值,弯曲强度为404.4 MPa、剪切强度为66.7 MPa、冲击强度为86.5 kJ/m~2;GB相较于TALC对复合材料的增强效果更好,使复合材料的综合力学性能得到进一步提高。     

基于PIF制备一种高性能聚苯硫醚复合材料

采用压力诱导流动成型(PIF)方法来调控聚苯硫醚(PPS)/玻璃纤维(GF)/碳纤维(CF)三元复合材料的本体结构。并对三元复合材料进行了傅立叶红外光谱分析(FT-IR)、形貌观察(SEM)、力学性能测试、动态力学测试(DMA)和DSC测试,考察了PIF成型的效果。结果表明,在该三元体系中,当CF的质量分数为0.5%时,PIF成型后的复合材料性能最佳,拉伸强度达到362.33 MPa,弯曲强度达到408.11 MPa,冲击强度达到14.35kJ/m~2。     

Microwave welding of high density polyethylene using intrinsically conductive polyaniline

The use of intrinsically conductive polymers in welding of plastics and composites offers the possibility of developing new welding methods. Intrinsically conductive polyaniline (PANI) composite gaskets were used to microwave weld high density polyethylene (HDPE) bars. Two composite gaskets were made from a mixture of HDPE and PANI powders in different proportions. Adiabatic heating experiments were used to estimate the internal heat generation and electric field strength in the gasket. During welding, the effects of heating time, heating pressure and welding pressure were evaluated. It was found that increasing the heating time and the welding pressure increased the joint strength. The maximum tensile joint strength was achieved using a 60 wt% PANI gasket with a heating time of 60 sec and a welding pressure of 0.9 MPa; this resulted in a tensile weld strength of 24.79 ± 0.34 MPa, which equals the tensile strength of the bulk HDPE.     

纤维增强树脂基复合材料的搅拌摩擦焊研究

利用搅拌摩擦焊实现了纤维增强树脂基复合材料的焊接,获得了焊接接头力学性能并分析了接头形成和断裂机制。结果表明,由于搅拌摩擦焊过程中搅拌针的摩擦剪切及对塑化材料的挤压作用,使树脂基体发生塑化并带动碳纤维迁移形成焊接接头,在搅拌头旋转速度950 r/min,焊接速度38 mm/min时,接头拉伸强度可以达到52.43 MPa,接近母材强度的51%,焊接接头的断裂机制主要为基体剪切断裂和纤维-基体界面脱粘。     

Effect of chemical etching of resistance wire surface on the strength and failure mechanism of the resistance-welded joint of polyetherimide composites

The surface modification of stainless-steel (SS) mesh was carried out by chemical etching for different time, and then, the etched SS meshes were used as the interlayer heating element for resistance welding of glass fabric-reinforced polyetherimide (GF/PEI) composite laminates. The hydrophobicity and tensile strength of the etched and untreated SS wires and interfacial shear strength (IFSS) between SS wire and PEI resin were investigated by dynamic contact angle (DCA) analyzer and single fiber pull-out test to evaluate the influence of the degree of chemical etching on the bonding strength of PEI resin and SS surface. Tensile lap-shear strength (LSS) and scanning electron microscope (SEM) analysis were performed to investigate the welding interface strength and fracture morphologies of the resistance-welded joint of the GF/PEI laminates. The hydrophobicity and tensile strength of SS wires were increased and decreased respectively with etching time (t_e). The IFSS of SS wire/PEI resin showed an improvement with t_e. The LSS was increased first and then decreased with t_e, and the optimal t_e was 30 min when LSS reached the maximum. Fracture analysis showed the main failure mode of the welded joints was the interlayer debonding when welding time (t_w) was insufficient. With the extension of t_w, the failure mode gradually switched into the intralayer tearing of the SS implant. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47879.     

Development of multiwalled‐carbon‐nanotube‐welded carbon fibers and evaluation of the interfacial strength in epoxy composites

Multiwalled carbon nanotube (MWCNT)‐welded carbon fibers (CFs) were prepared by a three‐step process, which included polyacrylonitrile (PAN) coating, MWCNT absorption, and heat treatment. The structure of these materials was characterized by scanning electron microscopy, Fourier‐transform infrared spectroscopy, and Raman spectroscopy. The MWCNTs were uniformly assembled on the surface of the PAN‐coated CFs and welded by a PAN‐based carbon layer after heat treatment. The contact angle of the MWCNT‐welded CFs in the epoxy resins was 41.70°; this was 22.35% smaller than that of the unsized CFs. The interfacial shear strength (IFSS) of the MWCNT‐welded CF–epoxy composite was 83.15 MPa; this was 28.89% higher than that of the unsized CF–epoxy composite. The increase in the IFSS was attributed to the enhancement of adhesions between the CFs and polymer matrix through the welding of the MWCNTs on the CFs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45027.     

Strong and Flexible Carbon Fiber Fabric Reinforced Thermoplastic Polyurethane Composites for High‐Performance EMI Shielding Applications

Electromagnetic shielding materials play a significant role in solving the increasing environmental problem of electromagnetic pollutions. The commonly used metal‐based electromagnetic materials suffer from high density, poor corrosion resistance, and high processing cost. Polymer composites exhibit unique combined properties of lightweight, good shock absorption, and corrosion resistance. In this study, a novel high angle sensitive composite is fabricated by combining carbon fiber (CF) fabric with thermoplastic polyurethane elastomer (TPU). The effect of stacking angle of CF fabric on EMI shielding performance of composite is studied. When the stacking angle of CF fabric changed, the electromagnetic interference (EMI) shielding effectiveness (SE) of CF fabric/TPU composite can reach a maximum of 73 dB, and the tensile strength can reach 168 MPa. In addition, the composite has anisotropic conductivity, which is conductive along the plane direction and nonconductive along the thickness direction. Moreover, the CF fabric/TPU composite manifests exceptional EMI‐SE/density/thickness value of 383 dB cm² g^?1, which is higher than most of current EMI shielding composites reported in literature. In summary, CF fabric/TPU composite is an excellent EMI shielding material that is lightweight, highly flexible, and mechanically robust, which can be applied to the field of aerospace and some intelligent electronic devices.     

聚乙烯管材热熔对接接头抵抗慢速裂纹扩展性能评价

采用应变硬化试验(SH)对不同焊接工艺下的聚乙烯管材热熔对接接头抵抗慢速裂纹扩展（SCG）性能进行评价。通过建立焊接温度梯度（190~250 ℃）、焊接压力梯度（0.6~1.4 MPa）和吸热时间梯度（40~140 s）试验，分析在不同焊接工艺参数条件下，不同聚乙烯管材热熔对接接头耐SCG性能的变化规律，探索冷焊及过焊2种典型缺陷对管材接头耐SCG性能的影响。结果表明，焊接温度、焊接压力和吸热时间都是影响管材热熔对接接头耐SCG性能的重要工艺参数，试验测得PE100, d_n110, SDR11型管材的最佳焊接参数为焊接温度230 ℃，焊接压力1 MPa及吸热时间100 s，当焊接参数选取过高或过低时，会造成管材接头出现过焊或冷焊缺陷，降低管材接头的耐SCG性能。     

碳纤维增强尼龙66复合材料的制备及性能

采用双螺杆挤出机熔融共混法制备了碳纤维(CF)增强尼龙66复合材料(PA66/CF),对其结构进行了表征,并研究了其力学性能。扫描电镜照片显示,在PA66/CF复合材料中,CF与PA66基体充分粘结在一起,其微观形貌表明,体系中碳纤长度为0.5~0.7 mm。力学性能测试发现,与尼龙66相比,PA66/CF复合材料各项力学性能指标均有大幅度提高。当加入4束碳纤维时,PA66/CF复合材料力学性能最佳,该复合材料的拉伸强度为200.2 MPa,与PA66相比提高了113.2 MPa;弯曲强度为280.2 MPa,比PA66提高了190.3 MPa;弯曲模量为13560.8 MPa,比PA66提高了10628.7 MPa;冲击强度为14.8 kJ/m^2,比与PA66提高了6.3 kJ/m^2。该PA66/CF复合材料密度较小、力学性能优良,可以广泛应用于风电叶片、发动机罩盖、仪表盘、车尾门等产品当中。     

The study of linear vibrational welding of moso bamboo

Moso bamboo (Phyllostachys pubescens) linear-vibration welded joints with three different combinations between the inner and outer surfaces were studied in this paper. The tensile-shear strength, the microstructures and welded layer thickness observed by SEM and the density profiles measured by X-ray densitometer of the welded samples have been considered and compared. The maximum average tensile-shear strength of outer-outer, inner-inner and outer-inner welded joints were 5.91, 7.15 and 6.24 MPa, respectively. And only the inner-inner welded joints have the bamboo failure after the shear test. The welded joint is composed of a lot of bamboo fibers entangled in the molten and flown intercellular materials which decide the final mechanical performance of the welded joints. The thickness of the outer-outer welded layer is the smallest and the inner-inner welded layer is the highest. However, the maximum density reached in the inner-inner welded joint is smaller than in the outer-outer welded joint owing to the different vascular distribution in the cross section of the moso bamboo. The relative density can be used to reflect the tensile-shear strength of the welded joints. The natural structure of bamboo really do have significant influences on the welded interface.     

PPS/PAI/CF复合材料摩擦磨损性能的研究

采用模压成型法制备了聚苯硫醚(PPS)/聚酰胺酰亚胺(PAI)合金及其碳纤维(CF)改性复合材料。测试分析了该复合材料的力学性能,并通过扫描电镜(SEM)对其摩擦磨损表面形貌进行了观察,探讨了复合材料的摩擦磨损性能;考察了PPS/PAI合金的最优配比及CF含量对PPS/PAI/CF复合材料性能的影响。结果表明:PAI的加入改善了PPS的力学性能,当PPS/PAI质量比为40/60时,PPS/PAI合金的力学性能最优;另外,CF的加入使PPS/PAI/CF填充复合材料的摩擦系数和磨损量大幅度下降,其中,当CF含量为30%时,PPS/PAI/CF填充复合材料的摩擦系数和磨损量较未填充PPS/PAI分别下降了66%和90%。     

Development of heating elements based on conductive polymer composites for electrofusion welding of plastics

Conductive polymer composites have been developed based on high-density polyethylene filled with carbon black (HDPE-CB), capable of generating heat when an electric voltage is applied. For each voltage value, the composite reached a constant value of equilibrium temperature, which obeyed a quadratic dependence on voltage and a linear dependence on electric power. The possibility of using such composites as heating elements (HE) for electrofusion welding of polyethylene adherents was evaluated in two modes, ''hard'', when high voltage was applied for a short welding time, and ''soft'', in which a stepwise regime of the applied voltage and a longer welding time were used. The latter provided a stronger welded joint. Using HE based on the HDPE-CB composites for welding of butt and lap joints of the polymer materials enabled to obtain welded joints with high strength.