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。     

涂膜工艺对预浸料物理性能的影响研究

为研究涂膜工艺对预浸料黏性寿命的影响,本文以中温环氧树脂为基体,改变涂胶辊的温度、烘胶的温度、烘胶的时间,设计了正交试验,测试了不同因素组合下胶膜面密度的稳定性;最后在相同含浸工艺条件下将9种胶膜制备成预浸料,测试了预浸料的黏性寿命.结果表明,涂胶辊的温度与烘箱的实测温度相当,涂膜工艺对胶膜面密度的均匀性和预浸料的黏性...     

单丝热熔法制备国产M40级高模量碳纤维预浸料及性能

主要介绍了高模量碳纤维/氰酸酯树脂预浸料单丝热熔制备技术,并对单丝热熔制备国产M40级高模量碳纤维预浸料制备过程影响预浸料质量的工艺参数进行研究,主要有胶液温度、纤维束张力、纤维束运行速率及其运行路径等。通过工艺试验得到适合国产BHM3/BS-4树脂单丝热熔预浸料的工艺参数:胶液温度控制为85~100℃,纤维束张力控制为2~5 N,纤维运行速率控制为0.35~0.45 m/s。采用单丝热熔法制备了国产BHM3碳纤维不同厚度的预浸料,各项性能均已达到进口M40B-3k碳纤维的工艺技术水平。     

直升机柔性杆用环氧树脂预浸料的研制

研制了用于制备直升机主传力系统中复合材料柔性杆件的改性环氧树脂基体及其RC10．800连续玻璃纤维预浸料。探讨了树脂基体组成、连续玻璃纤维窄带预浸工艺参数等变量对预浸料和复合材料性能的影响。选用的促进剂满足直升机柔性杆的技术要求和热熔工艺要求，满足此生产工艺要求。     

国内外预浸料制备方法

预浸料是增强纤维浸渍树脂基体后制备复合材料的半成品,其性能取决于其原料性能及加工工艺。本文综述了预浸料的分类,介绍了国内外热固性预浸料和热塑性预浸料的工艺制备,包括增强纤维、树脂基体、固化体系等原料的选择及其制备方法,并比较了各种方法的适用性及优缺点。     

阻尼构件结构胶膜的研制

研制了一种与粘弹性阻尼橡胶有良好粘接特性且可与碳／环氧复合材料预浸料共固化的耐温结构胶膜。讨论了该胶粘剂的主要成分及固化条件对胶粘剂力学性能的影响，并考核了这种胶粘剂的综合性能。     

977-2/T300和M21/T800复合材料性能研究

探讨了增韧环氧树脂977-2与T300碳纤维、增韧环氧树脂M21与T800碳纤维形成的单向带预浸料、织物预浸料以及复合材料层压板的性能。研究结果表明:M21/T800预浸料属于T800级材料,M21/T800复合材料的常规力学性能在纤维控制的项目上,高于其他三种材料;树脂基体及界面的性能与T300材料的相当,材料的韧性和抗损伤能力比T300材料有较大程度的提高;M21/T300织物预浸料的韧性和抗损伤能力优于977-2A/T300预浸料。     

磷酸盐基体及其纤维增强复合材料的研究-基体磷/金属元素摩尔比对工艺和材料性能的影响

本实验以自制的磷酸盐为胶粘剂,以金属氧化物为固化剂,玻璃纤维为增强材料,通过手糊成型再经热压制得了耐高温透波复合材料.测定了不同磷/金属元素[P/M(M=Al、Cr等)]摩尔比基体胶的粘度、固化时间等参数;并用XRD分析了材料基体组分,同时探讨了基体胶的P/M摩尔比对所制得复合材料性能的影响,确定了基体胶的最佳P/M摩尔比.     

复合材料用预浸料

３预浸料的质量控制预浸料的一些性能将直接带入复合材料 ,复合材料的性能取决于预浸料的性能。对于热固性树脂预浸料而言 ,在制造过程中 ,运输、储存期间均会发生化学变化。热塑性树脂预浸料在上述情况下虽不发生化学变化 ,但聚合物分子量、分子量分布、纯度、结晶形态等对预浸料和复合材料性能及成型工艺均有很大影响 ,如树脂体系组成的微小变化、工艺过程控制不当或偶然失误 ,都会对复合材料带来无法挽回的损害 ,因此 ,对预浸料必须进行严格的质量控制。国外已形成一整套严密地质量控制程序和方法 ,建立了保证预浸料制备过程各阶段性能的…     

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。     

改性氰酸酯的预聚工艺研究

本文研究酚醛环氧改性双酚A氰酸酯,用于制备热熔预浸料.双酚A氰酸酯和酚醛环氧树脂经过适当预聚后在室温下具有一定的粘附性,可制作出具有室温铺敷性的复合材料预浸料.将金属催化剂二月桂酸二丁基锡(DBTDL)加入改性体系,复合材料成型试验结果表明,DBTDL对树脂体系的预聚工艺有明显的改善作用,树脂体系可用于热熔工艺.     

耐高温无机防静电胶粘剂的制备及性能研究

以磷酸铝胶粘剂为基体,锑掺杂的二氧化锡(ATO粉)为导电填料,制备无机防静电胶粘剂。研究了ATO粉用量对该胶粘剂的热稳定性、表面电阻率、介电性能和力学性能等影响。结果表明:当温度为200～800℃时,防静电胶粘剂具有良好的热稳定性(其热失重率仅为6%);防静电胶粘剂的表面电阻率主要与介质材料的性能有关,当w(ATO粉)=5%～30%时(相对于磷酸铝胶粘剂而言),表面电阻率在4.2～5.0 MΩ/m2之间;当w(ATO粉)=25%时,防静电胶粘剂的介电性能最优,而力学性能变化不大。     

Crystallization and fiber/matrix interaction during the molding of PEEK/carbon composites

The objective of this work was to investigate the effects of molding conditions (molding temperature, residence time at melt temperature, and cooling rate) on the crystallization behavior and the fiber/matrix interaction in PEEK/carbon composites made from both prepreg and commingled forms. In order to investigate the crystallization behavior of the PEEK matrix, the molding process was simulated by differential scanning calorimetric analysis, DSC. The results show that the prepreg and commingled systems do not have the same matrix morphology; prepreg tape was found to be at its maximum of crystallinity, whereas the commingled system was found to be only partially crystalline. The results show that processing must be carried out at a temperature sufficiently high to destroy the previous thermal history of the PEEK matrix; this is an essential requirement to produce efficient fiber/matrix adhesion in the commingled fabric system. Optical microscopic observations also suggest that matrix morphology near the fibers is dependent on the melting conditions; a well-defined transcrystalline structure at the interface is observed only when the melt temperature is sufficiently high. However, the high temperature of molding can easily result in degradation of the PEEK matrix such as chain scission and crosslinking reactions. Thermal degradation of the matrix during processing is found to affect the crystallization behavior of the composites, the fiber/matrix adhesion, and the matrix properties. This effect is more important in the case of a commingled system containing sized carbon fibers because the sizing agent decomposes in the molding temperature range of PEEK/carbon composites. This produces a decrease of the matrix crystallinity and an elimination of the nucleating ability of the carbon fibers. A transition between cohesive and adhesive fracture is observed when the cooling rate increases from 30°C/min to 71°C/min for the composite made from the commingled fabric. This critical cooling rate is found to closely correspond to a change in the mechanism of crystallization of the PEEK matrix.     

磷酸镁水泥制备及性能研究

以磷酸二氢钾、氧化镁、硼砂和粉煤灰为原料,按一定比例制备磷酸镁水泥,以工作性能和强度为指标,研究了水胶比、氧化镁与磷酸盐摩尔比(M/P)、硼砂及粉煤灰掺量对磷酸镁水泥性能的影响;采用X射线衍射仪与扫描电子显微镜研究了磷酸镁水泥水化产物及粉煤灰对其结构和性能的影响。结果表明,当水胶比为0.34,M/P=3/1,掺10%硼砂和40%粉煤灰时磷酸镁水泥强度最高,达到54.2MPa。     

Mechanical Properties of Carbon Epoxy Prepreg Insert Phenolic Resin Injection Moldings

This study focuses on the insert-injection molding process. The thermoset composite inserts in this study were carbon fiber/epoxy(CF/Epoxy) prepreg sheets. The injected molded part was glass fiber contained phenolic resin(GF/PF). The CF/Epoxy was placed in the mold cavity prior to injecting GF/PF onto the inserted injection molded CF/Epoxy specimens. The role of adhesion between the inserted part and injected resin on the mechanical properties was evaluated by 3 point bending and impact tests. In addition, the effect of prepreg orientation on the mechanical properties of the prepreg inserted-injection molding system was investigated. It was found that the prepreg with unidirectional orientation significantly improved flexural and impact strength of the inserted injection molding composites, providing better support and resistance to bending and impact loading. The main failure modes of the specimens were structural and adhesive failure.     

Influence of magnesia-to-phosphate molar ratio on microstructures,mechanical properties and thermal conductivity of magnesium potassium phosphate cement paste with large water-to-solid ratio

This paper describes the influence of the magnesia-to-phosphate (M/P) molar ratios ranging from 4 to 12, on the properties and microstructures of magnesium potassium phosphate cement (MKPC) pastes with a large water-to-solid ratio (w/s) of 0.50. The setting behavior, compressive strength, tensile bonding strength and thermal conductivity of the MKPC pastes, were investigated. The results show that an increase in the M/P ratio can slow down the setting reaction, and clearly degrade the mechanical strengths, but clearly improve the thermal conductivity of MKPC pastes. Furthermore, micro-characterizations including X-ray diffraction, scanning electron microscopy and thermogravimetric analysis, on the MKPC pastes reveal that a lower M/P ratio can facilitate better crystallization of the resultant magnesium potassium phosphate hexahydrate (MKP) and a denser microstructure. Moreover, strong linear correlations are found between the mechanical strengths and the MKP-to-space ratio, and between thermal conductivity and the volume ratio of the unreacted magnesia to the MKP.     

Study on benzoxazine-based film adhesive and its adhesion properties with CFPR composites

In this paper, a benzoxazine-based (BZ) adhesive with high temperature resistant was developed by blending benzoxazine monomer and tetrafonctional epoxy monomer as matrix modifier and polyetherimide as toughening agent. The results show that benzoxazine-based film adhesive could be cured at 190 °C, and the cured film adhesive exhibited high temperature resistance and a high glass transition temperature of 224 °C. The 5% weight loss temperature in air was 400 °C and the char yield in nitrogen at 800 °C was 48%. The cured film adhesive has good ablation resistance. The fabricated benzoxazine-based film adhesive has high adhesion reliability, with single-lap shear strength of 23.20, 28.36 and 20.04 MPa at room temperature, 140 and 175 °C respectively. The curing process of the film adhesive matches well with that of carbon fiber reinforced BZ prepreg and the film adhesive has stable adhesion properties. Its biggest advantage is that, during storage and transportation, there is no need of refrigeration. After 60 days of storage for benzoxazine-based film adhesive at room temperature, its process performance and adhesion properties remain unchanged. It is expected that the benzoxazine-based film adhesive can be used in aerospace, high-speed rail and other applications.     

Thermal and air permeation properties of a carbon fiber/toughened epoxy based prepreg system

This study addresses thermal and air permeation properties of a new toughened prepreg system. Voids in the uncured prepreg structure can affect the void content in the final composite structure. A new, toughened prepreg system, commercially available for aircraft structural application, was utilized in this study. The prepreg was subjected to thermal and rheological characterization to understand the basic prepreg properties. These experiments were followed by a prepreg air permeation study to investigate prepreg processing and its influence on the prepreg structure. Crosslinking of the resin matrix was monitored with prepreg specimens without extracting resin from the prepreg. Along with thermal property measurements, the air flow rate significantly decreased in initial static experiments, followed by equilibrium permeability values. An air permeation model divided the air permeability into intralaminar and interlaminar permeabilities. Interlaminar air permeation was found to be more pronounced than intralaminar air permeation in this particular prepreg system. These permeation measurement results were explained using optical microscopy, proving that the application of vacuum could eliminate significant porosity in the laminate. Collectively, understanding prepreg thermal and air permeation properties was considered to be important; the voids in uncured prepreg may cause the voids in the final composite structure. Voids in the prepreg can be attributed to the heterogeneity and anisotropy of the toughened prepreg structure, resulting from particular prepreg processing techniques. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 5–16, 1997     

Analysis and characterization of prepreg tack

As part of an engineering analysis and experimental methodology to characterize prepreg tack, a compression-to-tension test was optimized to enhance reproducibility and generate intrinsic property data. With the resulting stress-strain compression and tension data, a theoretical model was developed to describe tack as a bulk viscoelastic property of a prepreg laminate stack. Using the viscoelastic analysis, four intrinsic material parameters to characterize prepreg tack could be defined. These were 1) relaxed modulus, 2) unrelaxed modulus, 3) relaxation time, and 4) initial void content of the prepreg stack. Relaxed and unrelaxed moduli of the prepreg stack were independent of temperature, while the relaxation time was highly dependent on temperature and matrix viscosity. In addition, the relaxation time was found to be influenced by resin/fiber content and prepreg surface characteristics, which also influenced the void content of the prepreg stack. Using these measured parameters, good agreement was observed between theory and experimental data for both the stress-strain curve of the tack test and the simplified compression tack index (CTI*), defined as the ratio of output energy of the prepreg stack during tensile unloading to input energy during compressive loading.