环氧树脂/芳纶纤维预浸料的质量控制试验方法研究

测定了环氧树脂／芳纶纤维预浸料的固化度（红外法）、不可溶分含量及其复合材料的力学性能与储存时间的关系。结果表明,固化度、不可溶分含量与储存时间之间在９５％的置信条件下呈显著的线性关系。固化度、不可溶分含量可以作为预浸料的质量控制参数,其试验方法可用于预浸料的质量控制。     

国外FRP预浸料发展概况

预浸料是用树脂预先浸渍,可以储存的纤维增强塑料（FRP）半成品,随时可以用来制造复合材料制品。预浸料有热固性和热塑性预浸料之分。因它们容易使用、性能稳定、空隙率低、模塑过程清洁等诸多优点,预浸料在复合材料工业中日趋普遍,前景甚好。     

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…     

两种方法对玻纤预浸料的树脂含量测试及不确定度比较

在生产过程中,树脂含量对于玻纤预浸料的性能具有重要的影响,不同的测试方法所测得的预浸料中的树脂含量也会有所不同。本研究采用溶解法和灼烧法对4组高硅氧/酚醛复合材料预浸料进行了树脂含量的测试,并对其不确定度进行评定,测试结果表明,溶解法测定预浸料树脂含量的数值偏低,灼烧法测定预浸料树脂含量的不确定度更小。对于玻纤预浸料树脂含量的测定,为获取更加准确的测试数据,建议采用灼烧法进行测试。     

预浸料技术的新进展

本文根据复合材料低成本制造技术，介绍了预浸料技术的新进展，包括可常温储存的预浸料；低温固化高温使用的预浸料；大丝束碳纤维预浸料和快速固化预浸料。     

预浸料技术的新进展

本文根据复合材料低成本制造技术，介绍了预浸料技术的新进展，包括可常温储存的预浸料；低温固化温使用的预浸料；大丝束碳纤维预浸料和快速固化预浸料。     

锥板粘度计法测定树脂及其预浸料的凝胶时间

介绍了用锥板粘度计测定树脂及其预浸料凝胶时间的方法,并通过实验与现行的电热板法进行了比较.结果表明锥板粘度计法具有设备简单、测试速度快、消除人为影响、重现性好和数据准确的特点.适于预浸料生产过程中间控制以及树脂及其预浸料的质量表征.     

值得关注的预浸料市场

预浸料是用控制量的树脂(热固性或热塑性)浸渍纤维或织物后形成的中间材料。浸渍技术有溶剂浸渍、热熔体浸渍、粉末浸渍等。预浸料可以"B阶"状态或部分固化后储存。预浸带或预浸布用于手糊、自动铺带、自动铺纤或某些缠绕成型工艺中。单向预浸带(所有纤维平行)是最常见的预浸料形式,它们提供单向增强。机织布及其他平面织物预浸料提供二维增强,它们一般成卷销售。还有用纤维预成型体和编织物制成的预浸料,它们提供三维增强。     

复合材料用预浸料

(续 5)4　预浸料的类型和性能4 1　预浸料的类型随着复合材料研究和开发的不断进步 ,使用领域日渐扩大 ,复合材料构件不同制造工艺、不同工作条件对预浸料也提出了不同要求。为了适应来自多方面的需要 ,新的预浸料不断出现 ,预浸料的类型不断增加。按物理状态分类 ,预浸料分成单向预浸料、单向织物预浸料、织物预浸料 ;按树脂基体不同 ,预浸料分成热固性树脂预浸料和热塑性树脂预浸料 ;按增强材料不同 ,分成碳纤维 (织物 )预浸料、玻璃纤维 (织物 )预浸料、芳纶 (织物 )预浸料 ;根据纤维长度不同 ,分成短纤维 (4 76ｍｍ以下 )预浸料、长纤…     

热熔膜法碳纤维/环氧树脂预浸料制备工艺

采用自制的环氧树脂膜与碳纤维一起热压制备预浸料,并通过正交试验设计改变热压温度、时间和压力这三个工艺参数来探讨制备预浸料时热压工艺参数对预浸效果的影响,制成的预浸料固化成复合材料后测定其力学性能,以此来确定预浸料的最优热压工艺参数。测得制备的预浸料挥发分质量分数为(0.6±0.1)%、树脂质量分数为(55±2)%。正交试验结果表明:当热压温度为60℃,时间为50 s,压力为1.5 MPa时,复合材料的拉伸强度最高。     

Thermochemical characterization of some thermally stable thermoplastic and thermoset polymers

The thermochemical and flammability properties of some thermally stable polymers considered for use in aircraft interiors are described. The properties studied include: (a) thermomechanical properties such as glass transition and melt temperature; (b) dynamic thermogravimetric analysis in anaerobic environment; (c) flammability properties such as oxygen index, flame spread and smoke evolution; and (d) selected physical properties. The thermoplastic polymers evaluated included polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated included epoxy, bismaleimide, a modified phenolic and polyaromatic melamine resin. These resins were primarily used in the fabrication of glass reinforced prepregs for the construction of experimental panels. Test results and relative rankings of some of the flammability parameters are presented and the relationship of the molecular structure, char yield, and flammability properties of these polymers are discussed.     

Development of an environmentally friendly solventless process for electronic prepregs

The most common commercial processes for manufacturing prepregs for electronic applications use solvent‐based resin systems. Solvents are not environmentally friendly and contribute to voids in prepregs and laminates. The resin impregnation process is performed in an open resin bath. This low‐pressure impregnation is conducive to voids in prepregs. Voids cause product variability, which is a major source of scrap in board shops. To eliminate these drawbacks, a solventless process, based on the concept of injection pultrusion, has been developed. The impregnation is performed in a die under pressure to minimize voids. In previous work, chemorheological and kinetic measurements were used to identify a potential epoxy‐based resin system. In addition, flow visualization with model fluids was used to establish the basic flow mechanism. Here we use the previous results to develop a mathematical model for the B‐staging process. A prototype B‐staging die has been built and used to verify the mathematical model. The results show that the model agrees well with the experimental data for low pulling speeds and slightly underpredicts the runs at high pulling speeds. The properties of the prepregs, the dielectric constant (DK) and dielectric loss (DF), have also been measured in this research. The measurements show that the solventless prepregs have acceptable DK and DF values according to the Institute for Printed Circuits FR‐4 designation (a permittivity and tangent loss standard). A microscope has been used to observe the void contents of the prepregs. The solventless prepregs have been compared against standard FR‐4 prepregs and shown qualitatively to have fewer voids. Based on the mathematical model, two potential process alternatives for the manufacture of solventless prepregs have been developed and analyzed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1136–1146, 2004     

Torsional strength of carbon fibre reinforced composites for the application as internal bone plates

The paper is concerned with comparative measurements of torsional strength and modulus of carbon fibre reinforced composites in the form of plates as used for internal fixation of bones. The carbon/carbon-composites have been prepared with sulfur modified CT-pitch, phenolic resin and polyphenylacetylene resin as matrix precursor. Carbon fibre reinforced plastic plates were processed using commercially available prepregs. The mechanical properties and especially the torsional strength data are discussed from the view-point of requirements in osteo-synthesis.     

Effect of NBR on epoxy/glass prepregs properties

Solid acrylonitrile‐butadiene rubber (NBR) was used in epoxy resin for toughening and also for increasing the tack of epoxy/glass prepregs. The NBR used in this study was a rubber with 33% acrylonitrile content. The changes in thermal and mechanical properties such as glass transition temperature (T_g), curing characteristics and lap‐shear strength have been studied. For this purpose, three types of prepregs with two levels of NBR content of 3 and 5%, were prepared. Prepregs were made by solvent type impregnation apparatus. In this method, resin impregnates satin textile glass fiber under the controlled and constant condition of line speed and oven temperature. Prepregs were B‐staged for about 3%. The cure characterization, T_g and flow behavior were evaluated using differential scanning calorimetry and rheological analysis. Results showed that increasing the rubber content caused the following effects: (a) delay in gel time of prepregs, (b) increase in activation energy of prepregs, and (c) decrease in total heat of curing reaction. It is interesting that NBR increased the tack of epoxy/glass prepreg but, had no effect on its resin flow behavior. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

无卤阻燃覆铜板制备方法的研究

以邻甲酚和甲醛缩合,得到高邻位线性的酚醛树脂,此酚醛树脂再与环氧氯丙烷（ECH）进行环氧化反应,合成得到了高性能酚醛环氧树脂,在此基础上加入DOPO提高其阻燃性,再用双酚A酚醛树脂对其进行固化,得到覆铜板用的胶液。通过环氧值,阻燃性,红外光谱测试,探讨了最佳实验条件为：含磷环氧树脂的合成温度在120℃左右,反应时间为4 h,最佳含磷量为2%。用盐酸丙酮法（标准HG2-741-72）测定所得树脂的环氧值达到0.497。     

Chemical toughening of epoxies. I. Structural modification of epoxy resins by reaction with hydroxy-terminated poly(butadiene-co-acrylonitrile)

In an attempt to toughen the epoxy resin matrix for fiber-reinforced composite applications, a chemical modification procedure of a commercially available bisphenol-A-based epoxy resin using reactive liquid rubber HTBN [hydroxy-terminated poly(butadiene-co-acrylonitrile)] and TDI (tolylene diisocyanate) is described. The progress of the reaction and the structural changes during modification process are studied using IR spectroscopy, viscosity data, and chemical analysis (epoxy value determination). The studies support the proposition that TDI acts as a coupling agent between the epoxy and HTBN, forming a urethane linkage with the former and an oxazolidone ring with the latter. The chemical reactions that possibly take place during the modification are discussed.     

Modeling the chemorheology of thermosetting resins during processing

The curing conditions determine the rheological changes in the resin during the lamination of prepregs into multilayered circuit boards. In order to specify the optimum curing conditions during lamination, it is necessary to understand the rheology of the resin as it cures. In this study, the chemorheological behavior of two commercial epoxy resins and one cyanate-based resin was characterized using an engineering model for the resin viscosity. A linear regression technique was used to evaluate the model parameters from the conditions at the minimum viscosity obtained during resin cures at constant heating rates. The technique was extended to predict the minimum viscosities reached by the resins when subjected to temperature conditions commonly encountered during lamination. The utility of the technique for specifying the curing conditions necessary to have a desired resin flow during lamination and for selecting resin systems for lamination based upon chemorheology has been demonstrated.     

Formation of voids in composite laminates: Coupled effect of moisture content and processing pressure

Void formation as a result of prepreg moisture content and processing pressure during cure was experimentally investigated in thermosetting composite laminates. This was achieved by determining the void contents of eight‐ply laminates fabricated from TenCate^® BT250/7781 E‐glass/epoxy prepreg at processing pressures of 1.7, 3.0, 4.4, and 5.8 atm. At each processing pressure, three types of laminates were fabricated using: (i) unconditioned prepregs (direct from the storage bag); (ii) prepregs conditioned at 25% relative humidity; and (iii) 99% relative humidity. Dynamics of prepreg moisture uptake during conditioning was measured using a moisture analyzer and was shown to exhibit Fickian diffusion behavior. The void contents of the cured laminates were found to vary from 1.6% to 5.0% depending on humidity environment the prepregs were exposed and the pressure applied during fabrication. The void contents of all laminates were observed to approach an asymptotic value of ∼1.6% as pressure was increased. The experimental results indicated the processing pressure applied during fabrication was increasingly carried by the fiber bed, reducing resin pressure during cure. Therefore, an enhanced void formation model was proposed through the addition of a pressure reduction factor and an asymptotic void content term. The proposed model was found to accurately predict the void content of laminates made of prepregs exposed to constant/varying humidity environments and fabricated at a wide range of processing pressures. POLYM. COMPOS., 36:376–384, 2015. © 2014 Society of Plastics Engineers     

酚醛树脂/碳化硼/聚硼氮烷复合物的固化行为及其热解性能

酚醛树脂作为一种热固性树脂基体具有广泛的应用。为了满足其作为高性能树脂基体在苛刻条件（耐高温和抗氧化）下的使用,进一步提高酚醛树脂的耐热性能并兼顾其工艺性能显得尤为重要。采用含有无机元素的耐热性聚合物（聚硼氮烷）和碳化硼纳米粒子协同改性酚醛树脂的方法,能够克服单独加入碳化硼导致的酚醛树脂固化温度升高的问题。固化动力学分析表明,加入聚硼氮烷的酚醛树脂改性体系,其固化转化率显著高于同温度下酚醛树脂或碳化硼改性酚醛树脂的转化率。同时,聚硼氮烷和碳化硼协同改性酚醛树脂固化物在高温阶段（800～1000℃）的热解稳定性较改性前有大幅度的提高。通过红外光谱分析了不同热解程度下酚醛树脂及其改性物的结构,进一步阐述了聚硼氮烷和碳化硼协同作用对酚醛树脂改性体系固化行为和热解过程的影响机制。上述采用耐热性活性聚合物和碳化硼陶瓷粒子协同改性热固性树脂的方法,有望在高性能复合材料树脂基体中得到运用。     

Pultruded fiber-reinforced polyurethane-toughened phenolic resin,I. Reactivity and morphology

A phenolic resin/polyurethane copolymer was synthesized by reaction of a phenolic resin, a blocked-polyurethane and p-toluene sulfonic acid. The copolymer provides a good balance between the processability (including pot life, reactivity) and toughness. The reactions that proceeded during the synthesis of the copolymer was investigated by IR spectroscopy. It was found that blocked polyurethane reacted with the hydroxy group of the phenolic resin. Glass fiber-reinforced composites showed excellent bonding between fiber and matrix as revealed by SEM photographs. An overlap peak was found from the DMA diagram; it indicated that an interaction existed between phenolic resin and polyurethane and that improved the toughness of the phenolic resin.