复合材料液体模塑成型技术

复合材料液体模塑成型技术(简称LCM)是指将液态聚合物注入铺有纤维预成型体的闭合模腔中，或加热熔化，预先放入模腔内的树脂膜，液态聚合物在流动充模的同时完成树脂／纤维的浸润并经固化成型为制品的一类制备技术。树脂传递模塑、真空辅助树脂传递模塑、树脂浸渍模塑成型工艺、树脂膜渗透成型工艺和结构反应注射模塑成型是最常见的先进LCM工艺技术。这类工艺的共同特点是将纤维预成型体放入模腔内，     

大型复合材料容器旋转固化测温装置性能实验研究

缠绕成型是连续纤维增强热固性树脂复合材料容器最常用的一种成型方法,而温度则是热固性树脂基复合材料缠绕固化成型的重要影响因素之一。在大型复合材料容器旋转固化成型过程中密闭固化炉或烘箱内的温度很高,无法利用现有的温度测量装备对其实施在线测量,进而为固化制度优化提供理论依据。该文提出一种应用于复合材料容器旋转固化状态下的无线测温装置,首先介绍其组成结构和工作原理,然后对其工作性能进行试验验证和调试,从而为优化热固性树脂基复合材料的固化工艺制度以及提高能源利用率提供一种理论工具。     

树脂传递模塑充填过程的数值模拟

树脂传递模塑成型（RTM）工艺是在一定温度及压力下把低黏度的树脂注入预先置有增强纤维的模具中,然后固化成型的一种复合材料液体成型方法。本文建立了RTM工艺充模过程的数学模型,并采用有限元/控制体积法实现了对复杂薄壁构件的充填模式、压力场和速度场的模拟。     

紫外光固化树脂及其复合材料研究进展

纤维增强树脂基复合材料(FRP)多采用热固化方式成型,成型周期长,无法满足汽车等领域复合材料结构快速、高效的生产要求。树脂紫外光固化技术具有固化速度快、生产效率高、环保节能等显著优势,可满足FRP大规模工业化生产要求。综合近年来紫外光固化树脂及复合材料领域的研究热点,主要从反应原理、固化动力学、树脂及配方研究、光固化复合材料成型工艺及应用等领域介绍目前的研究现状,对紫外光固化树脂及复合材料的未来发展进行简要展望。     

树脂传递模塑工艺中工艺参数对树脂-纤维界面的影响

本文系统研究了工艺参数对由树脂传递模塑成型的复合材料的拉伸强度和树脂-纤维界面的影响.这些参数包括注射压力和模腔/纤维毡的温度.在较低的注射压力和较高的成型温度下,纤维得到良好的浸润和粘结,成型复合材料的拉伸强度也较高.     

树脂固化仪在环氧树脂固化过程研究中的应用

<正>HLX—Ⅰ型树脂固化仪能快速定量追踪热固性树脂和树脂基复合材料在实际成型过程中的固化过程,是确定热固性树脂、胶粘剂和树脂基复合材料的配方筛选、最佳工艺条件(固化时间和温度)的选择以及生产质量控制和监测的有效工具。     

Nomex蜂窝夹层复合材料的成型工艺研究

针对Nomex蜂窝填充双马树脂基复合材料夹层结构在固化成型过程中易出现的蜂窝芯边缘塌陷问题进行研究。通过采用不同的成型工艺方法,以及对共固化工艺参数进行调整,研制出相应的双马来酰亚胺树脂基碳纤维/蜂窝夹层结构层板,并且对夹层结构的力学性能、内部质量以及平面拉伸性能进行测试。在此基础上分析了成型压力参数对夹层结构质量的影响。相关工艺试验表明蜂窝芯塌陷的原因主要是固化过程中蜂窝芯边缘的滑移引起的蜂窝局部失稳,通过采取分步成型、蜂窝先胶接后修型的方法能够有效地解决Nomex蜂窝夹层结构填充双马树脂基复合材料结构成型过程中的蜂窝芯塌陷问题。     

复合材料RTM和VIP工艺技术培训班通知

正中国硅酸盐学会玻璃钢分会文件中硅玻璃钢分会秘发[2014]05号RTM(Resin Transfer Molding)成型工艺,即在模腔中铺放设计好的增强材料预成型体,在压力或真空或两者共同的作用下将低粘度的树脂注入模腔,树脂在流动冲模的过程中完成对增强材料的浸润并固化而得到复合材料制品的工艺方法。该工艺具有工作环境好、低能耗、高效率、低投资且工艺适应性强等优点,已广泛用于建筑、交通、电讯、卫生、运动器材以及航空航天     

复合材料RTM和VIP工艺技术培训班通知

正中国硅酸盐学会玻璃钢分会文件中硅玻璃钢分会秘发[2014]05号RTM(Resin Transfer Molding)成型工艺,即在模腔中铺放设计好的增强材料预成型体,在压力或真空或两者共同的作用下将低粘度的树脂注入模腔,树脂在流动冲模的过程中完成对增强材料的浸润并固化而得到复合材料制品的工艺方法。该工艺具有工作环境好、低能耗、高效率、低投资且工艺适应性强等优点,已广泛用于建筑、交通、电讯、卫生、运动器材以及航空航天     

吸胶膜对复合材料构件固化过程中树脂流动行为的影响

热固性树脂基复合材料构件成型过程中的树脂流动行为决定了其最终成型后的纤维体积分布情况,严重影响构件的最终成型质量。而吸胶膜作为预浸料中的多余树脂流出构件后的吸收载体,其材料特性对树脂的流动过程起主导作用。以吸胶膜为关注重点,基于AS4/3501-6复合材料体系,建立了厚截面复合材料构件在热压罐中固化压实的仿真模型,模型包括了固化反应、热传导和紧密压实三个模块。模型与实验中构件的压实情况对比,验证模型的可行性。通过模型计算结果研究了吸胶膜的孔隙率、渗透率及厚度等关键参数在压力、温度等工艺条件的协同作用下对树脂流动行为的影响规律。结果表明:吸胶膜的孔隙率和厚度作为吸收树脂载体的空间度量,对构件的最终压实厚度起主要作用;吸胶膜的渗透率通过树脂流动速度影响固化压实过程,渗透率过小时,构件的压实厚度明显减小。     

A structure and property based process window for void free thermoset composites

A process window providing guidelines to minimize internal stress levels and to prevent void formation during cure of thermoset composite materials is presented. A model taking into account the applied pressure and the level of stress borne by the fiber assembly was introduced to calculate the hydrostatic internal stress state in the resin during cure. Based on the fundamental mechanisms of matrix shrinkage and evolution of viscoelastic properties under the given processing conditions, the internal stress in the resin was calculated as a function of fiber volume fraction, fiber stacking sequence, applied pressure and resin conversion. This level of stress is compared to a criterion for void initiation in the resin. A process window was hence constructed for preventing void formation during cure. Composite laminates with different stacking sequences and fiber volume fractions were cured with different applied pressures within and out of the process window boundaries. The composite void contents were measured and correlated perfectly with the process boundaries. This process window construction taking into account the material vis‐coelastic properties and the composite architecture is a unique tool for determining optimum process condition of composite laminates.     

竹原纤维/聚乳酸纤维基复合材料的拉伸性能

本文采用竹纤维作为增强材料,聚乳酸作为基体,混合编织了两种衬经衬纬针织物,根据聚乳酸熔点较低的特点,利用热压复合制备形成竹原纤维/聚乳酸复合材料。此复合材料在自然环境下能够降解为绿色环保型复合材料。在复合材料的应用中,应用设计是必不可少的,而拉伸试验的目的恰是为此。在万能强力机上通过对复合材料的拉伸性能测试分析发现,复合材料板材的纵向拉伸性能好于横向和斜向,同时12根针织线圈捆绑纱形成的复合材料板材拉伸性能明显好于6根捆绑纱形成的板材,而且竹原纤维/聚乳酸复合材料板材的断裂为韧性断裂。     

On‐line mixing during injection and simultaneous curing in liquid composite molding processes

Liquid composite molding (LCM) processes such as resin transfer molding (RTM) and vacuum assisted RTM (VARTM) are used to manufacture high quality and net‐shape fiber reinforced composite parts. All LCM processes impregnate fiber preforms packed in a mold cavity with a thermoset resin. After the preform is fully saturated, the injection is discontinued but the resin continues to cure. Once the curing step is complete, the part is de‐molded. The resin has to be mixed with a curing agent to cure. Typically, the resin and the curing agent are mixed together in a pressure pot before the injection. This has several disadvantages, such as storage of large amounts of hazardous polymerizing resin, wastage, and cleaning of cured resin from the injection line. This paper proposes the implementation and calibration of an alternative to this technique. The approach is to mix the curing agent with the resin as the resin enters the mold through a separate system featuring two feed‐lines. Such a system will enable one to maintain a uniform gel time throughout the part by varying the mixing ratio of resin and the catalyst during the injection. An experimental study of such on‐line mixing to obtain simultaneous curing and to reduce the overall curing time is conducted and presented in this paper. Implementation of a control scheme that varies the curing agent during injection and its effect on cure time is benchmarked with the process in which the percentage of curing agent is held constant. The gel time for the fabricated parts was reduced by 20–25% by continuously varying the percentage of curing agent during injection. POLYM. COMPOS., 26:74–83, 2005. © 2004 Society of Plastics Engineers     

一种双酚A型氰酸酯树脂流变特性及其改性研究

本文采用平板法研究了一种双酚A型氰酸酯树脂的流变特性,通过恒温预固化的方法对其进行改性,并借助红外光谱、差示扫描量热法(DSC)和凝胶渗透色谱法(GPC)等手段分析了预固化对氰酸酯树脂化学结构的影响.在此基础上,针对S-2玻璃纤维/氰酸酯复合材料层板,采用热压机工艺考察了加压时机和预固化对层板成型质量的影响.研究结果表明,该氰酸酯树脂反应活性低且流动性高,热压工艺中树脂流动不易控制;预固化可使氰酸酯树脂发生一定程度的自聚反应,从而降低其流动性,可明显改善氰酸酯树脂的工艺性,提高了层板的成型质量.     

快速固化环氧树脂/碳纤维复合材料的性能

利用差示扫描量热分析仪研究了一种快速固化环氧树脂体系的固化工艺参数,确定了以真空辅助树脂灌注工艺制备快速固化环氧树脂/碳纤维复合材料的成型方法,并与常规固化环氧树脂体系制备的碳纤维复合材料进行对比,采用傅里叶变换红外光谱仪对两种材料的树脂基体进行了分析,考察了两种复合材料的纤维含量、孔隙率及力学性能,最后通过扫描电子显微镜观察了快速固化树脂基体与碳纤维的界面结合性。结果表明,快速固化树脂在99℃下固化6 min后固化度可达96%,能够大幅缩减碳纤维复合材料的成型时间,以其制备的碳纤维复合材料拉伸强度比常规固化环氧树脂复合材料高11.20%,弯曲强度高16.92%,纵横剪切强度高7.44%,快速固化树脂与碳纤维界面结合性良好。     

Improvement of mechanical properties of structural thermoplastic composites using a reactive (low molecular weight) matrix component

An innovative manufacturing process for continuous fiber composites with the polymeric matrix made up of polypropylene and epoxy resin, as a model reactive low molecular weight component, was developed; variable process parameters give rise to different morphologies of matrix components surrounding the woven fabric reinforcement. Furthermore, the combination of both thermoplastic and thermosetting polymers permitted intimate fibers impregnation, typical of thermosetting matrix composites, with short process cycle time, which usually occurs in manufacturing process of thermoplastic matrix composites. Polypropylene (PP) films, glass fibers fabric, and epoxy resin film were used to produce flat composite through film‐stacking technique. The preparation process focused on control of both epoxy resin cure process and polypropylene melting. The process was able to induce the two matrix components to form either a planar (sandwich‐like) structure or a three‐dimensional (3D) network by means of controlling the process parameters such as pressure and heating rate. The strong enhancement of the mechanical properties (Young's modulus and tensile strength of the composites with the 3D structure were almost twice as high of those of the composites with sandwich‐like matrix structure) was due to the different microstructures produced by the interplanar flow of the thermoplastic polymer. POLYM. COMPOS., 31:1762–1769, 2010. © 2010 Society of Plastics Engineers.     

碳纤维湿法缠绕用环氧树脂基体研究

以TDE-85树脂和AFG-90树脂为主体树脂,混合芳香胺为固化剂,研究了一种适合于碳纤维复合材料湿法缠绕成型的树脂配方。结果表明,该树脂的黏度低(＜550 mPa·s)、适用期长,其浇铸体具有优异的力学性能,其拉伸强度为107 MPa,拉伸模量为4．09 GPa,弯曲强度为161 MPa,弯曲模量为3．88 GPa,断裂伸长率超过6%。用其制备的T-700碳纤维缠绕复合材料界面粘接好,NOL环层间剪切强度达到66．8 MPa,拉伸强度达到2．44 GPa。     

Microwave irradiation of nadic-end-capped polyimide resin (RP-46) and glass–graphite–RP-46 composites: cure and process studies

Microwave energy was investigated to cure nadic-end-capped polyimide precursors (RP-46 resin) using a Cober Electronics Model LBM 1.2A/7703 microwave oven at a frequency of 2.45 GHz. Both neat resin samples and glass cloth and hybrid glass cloth–graphite cloth–RP-46 resin composites were studied. For the resin studies, the effect of various parameters, such as power level, sample size, processing temperature, time, and graphite fiber absorber, were investigated. The variables investigated with the composite study were the power level, mold material, vacuum, and low pressure. The results showed that microwave energy was effective in curing both neat resin samples and composite specimens. The presence of a small quantity of absorber (chopped carbon fiber) accelerates the cure dramatically. Moreover, soapstone mold material was found to be an efficient absorber for glass and glass–graphite composite processing, causing an effective cure in less than 1 h. Glass and glass–graphite hybrid composites with flexural strengths of 372–588 MPa (54–85 ksi) and moduli of 28.7–31.7 GPa (4.2–4.6 Msi) have been fabricated. This is equivalent to 50 to 80% of the properties of composites fabricated by conventional means. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2391–2411, 1999     

Processing‐interphase‐property relationship in fiber‐reinforced thermosetting‐matrix composites

Fabrication of thermosetting‐matrix composites is based on a critical step of cure, which involves applying a predefined temperature cycle to a fiber‐resin mixture. Several temperature‐dependent mass transport processes occur in the vicinity of the reinforcement fiber, leading to the formation of an interphase region with different chemical and physical properties from the bulk resin. The cure cycles applied on the macroscopic boundaries of the composite govern the microscopic cure kinetics near the fiber surface, which in turn determines the interphase and composite properties. A predictive approach to directly linking the cure cycles and final composite properties is not presently available and is established for the first time in this paper. A multiscale thermochemical model is developed to predict the concentration profile evolution with time near fiber surfaces at various locations across the composite thickness. The concentration profiles at the gelation time are mapped to modulus profiles within the interphase region, and a finite element analysis is used to determine the overall composite modulus in terms of the constituent interphase, fiber, and matrix properties. Relevant numerical results are presented for the first time where the composite modulus is directly linked to the cure cycle and interphase formation parameters without assumed structures or properties of the interphase. The results provide useful information for selecting material components and cure cycles parameters to achieve desired interphase and composite properties. POLYM. COMPOS., 26:193–208, 2005. © 2005 Society of Plastics Engineers     

Key factors affecting permeability measurement in the vacuum infusion molding process

The composites industry, under increased environmental constraints, is seeking to shift from existing open mold manufacturing processes for composite parts. A promising manufacturing technology known as the vacuum infusion molding process is gaining acceptance among composite-parts manufacturers since it involves low tooling cost and allows complete elimination of volatile organic compounds (VOC). The process is similar to the resin transfer molding process; however, in the vacuum infusion technique, a polymeric film, often referred to as vacuum bag, replaces the stiff mold cover. The film is sealed against the lower half of the mold, at the periphery. Air expelled from the mold cavity results in the compaction of the reinforcement by the atmospheric pressure present on the outer side of the polymeric film. Finally, resin impregnates the mold cavity, usually through a resin distribution channel. The process is mainly developed for large-scale structures, where material cost is an important parameter and users cannot afford any production pitfalls. Among process parameters that affect resin flow in the vacuum infusion molding process is the permeability of the reinforcement stack, which has to be measured and evaluated taking into consideration the requirements of the process. A possible approach is the definition of a parameter that defines the maximum infused length, and this parameter will take into account the structure of the reinforcement, the resin viscosity, the fiber volume fraction and inlet geometry.