国产湿可剥布对T300复合材料胶接性能的影响

以改性环氧树脂为主体树脂制备了国产高温湿可剥布。通过拉伸剪切强度和浮辊剥离强度等测试，对湿可剥布与国产固化预浸料固化工艺的匹配性进行了研究。结果表明，高温湿可剥布适用于国产树脂固化工艺。采用该湿可剥布与国产预浸料匹配使用，并进行了粘接性能研究发现拉伸剪切强度≥20 MPa，浮辊剥离强度≥25 N/cm，夹层件平面拉伸强度≥1.9 MPa。     

可剥布表面处理对复材胶接质量的影响

复合材料的胶接质量取决于多种物理和化学因素,主要与可剥布的成分、胶接面微观形态、环境湿度等因素息息相关。为研究可剥布处理后复材表面形貌特征和表面自由能对胶接质量的影响,通过扫描电子显微镜、表面张力仪等检测手段,建立了复合材料表面特性与断裂韧性之间的关系。结论表明表面清洁度对胶接质量有直接影响,而表面自由能对胶接质量的影响尚未得到证实。     

高树脂含量预浸料工程应用研究

以双马树脂碳纤维织物预浸料为对象,通过制作试验件,对比分析不同吸胶材料及其工艺组合的吸胶能力,在保证产品性能的前提下,制订了可剥保护层和干玻璃布吸胶的工艺方法,并将此方法应用于典型零件的制造,在质量控制方面取得了明显效果。     

吸波复合材料预浸料制备工艺研究

对吸波复合材料预浸料制备工艺特性及存在的问题进行了分析,借鉴以玻璃布生产蜂窝夹芯材料时所使用的机械化涂胶工艺,提出了由双槽辊式涂胶法与喷涂浸胶法组合而成的机械化预浸料制备工艺。工艺特性分析表明:喷射涂胶法能够有效地解决吸收剂材料在预浸料中均匀分布、含量可控的技术难题,达到材料产品吸波性能稳定、可靠的质量要求;双槽辊式涂胶法使得纤维布的浸胶效果良好,辊压复合而成的夹芯结构预浸料片铺层工序简化,质量可靠性高。     

环氧湿剥离布与国产预浸料匹配粘接适用性研究

采用环氧树脂为主体树脂制备了一种高温固化湿剥离布。通过T-B外推法和流变性能测试,对湿剥离布与国产高温固化预浸料固化工艺的匹配性进行了研究。结果表明,湿剥离布适用于国产5224树脂固化工艺。采用该湿剥离布与国产5224/CCF300预浸料匹配使用,并进行了粘接性能研究,结果表明,湿剥离布处理后的5224/CCF300复合材料粘接性能与打磨后处理的复合材料粘接性能相当,比干剥离布处理的复合材料剪切强度提升13.4%,断裂韧性提升13.2%。     

零吸胶工艺复合材料层板成型质量与预浸料特性关联分析

针对3种国外产碳纤维/环氧预浸料,测试表征了预浸料的工艺特性,并采用热压罐零吸胶工艺制备了复合材料层板,考察了工艺条件对层板厚度和内部缺陷的影响,分析了成型质量与预浸料特性之间的关联性,进一步研究了层板弯曲性能、层间剪切性能对成型质量变化的敏感性。实验结果表明,由于零吸胶工艺树脂流动受到很大限制,预浸料树脂含量不均容易造成所成型层板厚度不均、表面不平整,另外,预浸料树脂流动性小的体系在层间容易出现明显富树脂现象;零吸胶工艺夹杂空气主要在真空作用下通过铺层内的通道排出,因此预浸料气体渗透率和成型封装方式对孔隙缺陷有重要影响;实验范围内,工艺条件的改变没有显著影响所成型层板的短梁剪切性能和弯曲性能。研究结果对于预浸料选择和国产高性能预浸料的开发具有重要参考价值。     

碳纤维预浸料成型自行车结构件气泡原因及解决方案

使用UTS-50/B201预浸料通过袋压法成型工艺制作自行车车架,在固化及胶接保温处理后均产生了气泡,增加了后续劳动强度和工作时间,从而增加了生产成本,降低了生产效率。研究结果表明,通过调整树脂体系的粘性、热焓、凝胶时间以及预浸料的树脂流动度,可有效减少乃至消除制品中的气泡。     

吸湿对氰酸酯胶膜蜂窝夹层结构胶接性能的影响

采用氰酸酯预浸料、氰酸酯胶膜和Nomex纸蜂窝,利用热固化成型方法制备了氰酸酯胶膜蜂窝夹层结构。分析了Nomex纸蜂窝、氰酸酯预浸料、氰酸酯胶膜的吸湿行为,研究了吸湿对氰酸酯胶膜粘接的夹层结构破坏模式的影响,分析了吸湿在氰酸酯胶膜粘接夹层结构中的作用机理,以此为基础提出了减小或消除吸湿影响的措施。结果表明,氰酸酯胶膜及氰酸酯预浸料的吸湿量可以忽略。Nomex纸蜂窝中的湿气对夹层结构的胶接会产生不利影响,湿气的存在会影响胶粘剂对蜂窝的浸润,并且湿气中的水分还会催化氰酸酯的反应,在粘接固化过程中加速胶粘剂的凝胶和黏度增大。为消除纸蜂窝吸湿对胶接的不利影响,采取措施控制胶接环境和待胶接材料的贮存环境、在胶接前充分干燥待胶接材料等措施,可以达到降低待胶接蜂窝中的湿气含量,进而减小其对夹层结构胶接影响的效果。     

改性天然胶乳应用于玻纤橡胶基布表面浸胶处理的研究

叙述利用环氧化改性天然乳胶配制浸胶浆进行玻纤橡胶基布表面浸胶处理．处理布用于矿山导风简和夹布胶管增强基布。并对处理布的强力，制品的布与布、布与胶的层间附着力进行了评价。     

芳纶纤维/环氧树脂预浸料界面相容性的方法探究

预浸料要求树脂基体和增强纤维具有良好的匹配性,为了提高芳纶纤维/环氧树脂预浸料的界面相容性,本文从芳纶纤维表面改性及增韧技术两个方面进行综述,讨论了芳纶纤维物理改性和化学改性方法的优缺点,分析了界面增韧及环氧树脂基体的不同增韧途径,重点介绍了聚氨酯/环氧树脂互穿网络体系.认为芳纶纤维的偶联剂表面处理和聚氨酯增韧环氧树脂相结合,是提高芳纶纤维/环氧树脂预浸料层间剪切强度的的可行途径.     

炭纤维预浸带表面状态的影响因素及改进机理研究

通过对不同结构预浸带的对比研究,得出了具有良好表面状态单向预浸带所具有的结构,并且从微观上研究了纤维与树脂的结合方式,得出了影响其表面状态的原因。通过对树脂体系的改进,使纤维能够处于树脂体系的交联结构之中,提高了横向撕裂强度,从而改进了单向预浸带的表面状态。     

Properties of carbon fiber composite laminates fabricated by coresin film infusion process for different prepreg materials

A new cocured process called coresin film infusion (co‐RFI) process, which combines RFI process and prepreg/autoclave process, was introduced and four kinds of commercial carbon fiber prepreg material systems and a kind of resin film were applied to fabricate co‐RFI laminates. The compatibility between the resin film and the prepreg matrix and the application of co‐RFI process were investigated based on the resin flowability, glass transition temperature of cured resin, processing quality of laminate, and variation in resin modulus on cocured interphase region measured by nanoindentation. Furthermore, mode I (G_IC), mode II (G_IIC) delamination fracture toughness, and flexural strength and modulus were measured to evaluate the mechanical properties of cocured laminates with different prepreg materials. The experimental results show that thickness and fiber volume fraction of co‐RFI laminates with the four kinds of prepreg materials are similar to those of prepreg laminates and RFI laminate with acceptable differences. In addition, there are no obvious defects in co‐RFI laminates. Moreover, the reduced modulus of resin at cocured interface and glass transition temperature values of the mixed resin reflect good compatibility between prepreg matrix resin and RFI resin. The G_IC, G_IIC values, and flexural performances of cocured laminates lie between and even exceed those of prepreg laminates and RFI laminates, indicating no weakening effect in the cocured interface. Therefore, the co‐RFI process is believed to effectively fabricate composite with low cost and it can be applied using various prepreg systems. POLYM. COMPOS., 34:2008–2018, 2013. © 2013 Society of Plastics Engineers     

Effect of an Atmospheric Pressure Plasma Treatment on the Mode I Fracture Toughness of a Co-Cured Composite Joint

In this study, the surface of a composite prepreg was treated using an atmospheric pressure plasma in an attempt to improve the fracture toughness of a co-cured joint system. Three gas mixtures were investigated; helium, helium/nitrogen, and helium/oxygen. The processing parameters of the system were varied to obtain the maximum increase in surface energy of the prepreg. A He/O₂ plasma was found to be the most efficient treatment, giving the largest increase in surface energy in the shortest time. Co-cured joints were then fabricated using prepreg that had been treated with various plasmas. A modest 15–18% increase in the Mode I fracture toughness was achieved. However, the locus of failure remained interfacial. It was also observed that a He/O₂ plasma treatment could be detrimental to joint toughness for long treatment times.     

Prepreg aging in relation to tack

Thermoanalytical measurements and tack tests were both performed using a commercially available carbon fiber/epoxy prepreg system (Hercules 3501–6) to examine changes caused by aging as they affect handling and processability of thermosetting matrix-based composites. Combining these techniques, a relationship between prepreg bulk and surface characteristics in relation to aging was investigated. Isothermal kinetic studies at low temperatures showed maximum conversions (α_m) that increased with increasing cure temperatures. In addition, a linear relationship between glass transition temperatures (T_g) and conversions (α) was observed regardless of aging (or cure) temperatures. Energy of separation of prepreg stacks, which may be viewed as a measure of prepreg tack, showed a maximum value at a specific temperature. The maximum energy of separation was observed in the temperature range of 20–25°C above the glass transition temperature for a given sample. However, the maximum energy of separation values decreased with increasing aging times (or conversions), implying that prepreg tack was a viscoelastic property rather than a viscous property of the resin matrix in the prepreg.     

Bonded aerospace repairs under tensile loading: Wet chemical surface treatment and selected environmental conditions

Repair of composite structures and the impact of demanding environmental conditions is a crucial issue for the aircraft industry because of the increasing use of composites in modern aircraft. Consequently, the impact of environmental conditions common for aircraft applications on repair specimens in comparison to nonrepaired specimens is studied. All specimens are produced from a woven carbon fiber-reinforced epoxy-based prepreg. For the repair-specimens, an epoxy-based film adhesive is used for the soft patch repair approach. During the repair process, the surface of the precured prepreg is prepared by a mechanical method (sanding) and an additional chemical functionalization, respectively. Moisture absorption of the repair specimens is independent of the surface preparation method and higher for the repaired than for the nonrepaired specimens. The key influencing environmental conditions for the tensile strength and the failure mode of the repair specimens are elevated temperature testing as well as hot/wet conditioning and conditioning in deionized water. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47506.     

Toughened carbon fiber prepregs using combined liquid and preformed rubber materials

Model epoxy resin formulations were modified with defferent concentrations of liquid rubber and preformed crosslinked rubber particles and impregnated into unidirectional carbon fibers. The liquid rubber was used to increase the mode I fracture toughness of the interlayer toughened prepreg systems, which already have high mode II fracture properties. In this paper it is shown that the mode II fracture toughness is not sacrificed by the incorporatiom of carboxyl terminated butadiene acrylonitrile rubber (CTBN) in the matrices, while mode I fracture toughness can be increased by as much as 100%.     

The Effects of Copper Oxides on the Curing Behaviors of Bismaleimide Triazine Prepreg

The effect of copper oxides on the curing behaviors of the bismaleimide triazine (BT) prepreg is studied with infrared spectroscopy (IR), attenuated total reflection infrared spectroscopy (ATR), and X‐ray photoelectron spectroscopy (XPS). The result of IR analyses indicates that there is a concentration distribution present in the prepreg surface layer and the outer surface layer contains less cyanate, imide, and epoxide but more triazine groups than the inner layer. From ATR, it is concluded that the cuprous oxide attracts more cyanate ester resins but less bismaleimide resins from the prepreg to its surface than the cupric oxide. The copper surface affects the curing extent of the BT resin in contact and the cupric oxide has a more pronounced effect than the cuprous oxide, and this surface effect can extend to at least two microns deep into the BT prepreg from the contacted interface. The XPS results confirm that the BT/CuO interface contains more thermally stable and polar functional groups than the BT/Cu₂O interface, and both two copper oxides attract only a small amount of brominated epoxy resin onto their surfaces. These results are attributed to the difference in preferential adsorptions and catalytic curing effects of two copper oxides on the BT prepreg in contact.

The intensity changes of IR bands obtained from BT prepreg during cure.     

Determination of prepreg tack

Prepreg materials — fibre-reinforcement preimpregnated with uncured resin — are widely used for the manufacture of large composite material components. Current commercially available prepreg materials often show significant variations in tack strength, from point to point within a sheet and from sheet to sheet. Such inconsistencies can lead to void formation in the final composites laminate. This paper describes the techniques and apparatus developed for the investigation of the surface tack strength of adhesives in general and of prepreg materials in particular, as a function of contact time and pressure and of rate of separation. It is hoped that the more detailed knowledge of prepreg tack will enable the production of more consistent material and hence the manufacture of improved quality composite laminates.     

磷酸盐基体及其纤维复合材料的研究--预浸料制备及其成型工艺

本文对无机磷酸盐体系进行研究，考察了磷／金属元素摩尔比(P／M)、含水量变化对胶粘剂性能的影响以及基体胶P／M变化对基体胶性能的影响，确定了合适的胶粘剂和基体胶配比，并用其制预浸料。通过热失重TGA分析以及考察加工成型过程中工艺参数变化对复合材料介电性能、力学性能的影响，优化了预浸料热压成型工艺条件。     

球面天线罩下料模板的设计方法

本文针对球面天线罩在预浸料铺覆过程中铺覆角度无法精确控制、铺覆操作难等问题进行研究,应用有限元分解的思想,将球面分解为一系列小平面,并由这些小平面拟合出了预浸料铺覆所需下料模板的AutoCAD模型。按照该模型数控加工出的下料模板实际使用效果良好。