先进树脂基复合材料RTM成型工艺研究及应用进展

复合材料的成型工艺是改进并提升先进树脂基复合材料性能的关键,而树脂传递模塑(RTM)成型工艺是一种环保高效、成本低、高精度的闭模成型工艺。概述并分析了传统RTM成型工艺过程及优缺点,并对高压树脂传递模塑成型(HPRTM)、轻质树脂传递模塑成型(LRTM)、真空辅助树脂灌注工艺(VARTM)、西门(Seeman)树脂浸渍技术(SCRIM P)等RTM衍生成型工艺的研究进展与应用进行了介绍分析。     

真空辅助RTM工艺中孔隙的形成机理及实时控制研究

根据国内外的研究成果对真空辅助树脂传递成型(RTM)工艺过程中气泡的形成机理进行了分析总结,同时介绍了几种真空辅助RTM实时过程控制方法.研究结果表明,实时过程控制能够减少孔隙形成的几率,改善流动前沿均匀性,缩短注胶时间,是提高复合材料产品质量的重要方法.     

RTM树脂材料及其辅助成型工艺研究进展

简要介绍RTM工艺的成型原理,详细介绍用于RTM的新型树脂及改性树脂材料的研究进展情况、各种RTM辅助成型的工艺进展情况,并展望RTM技术在航天航空等领域的应用。     

高性能复合材料树脂传递膜技术(RTM)研究

树脂传递模塑法（RTM）是一种低成本、效益好的复合材料成型工艺。研究了RTM用树脂体系、预成型技术、成型模具、成型工艺以及RTM在航空航天领域的应用。     

模拟液态模塑成型软件

<正> 美国ESI集团公司(ESI GROUP)已推出一种用于辅助设计复合材料部件制造应用工艺的软件包,适用于树脂传递模塑(RTM)、真空辅助树脂传递模塑(VARTM)和树脂薄膜浸渍成型(RFI)工艺。     

软模/真空辅助RTM工艺用模具设计与制备

以一个典型构件缩比件为例,介绍了软模及真空辅助RTM工艺用模具的设计和制备过程.实践证明,这种工艺可应用于复杂结构复合材料构件成型技术领域.     

树脂传递模塑（RTM）成型工艺及应用

本文概述了树脂传递模塑(RTM)的成型工艺过程及其应用前景。由此可了解 RTM 技术的全貌。通过对 RTM 与其它几种主要的复合材料加工工艺的比较,如SRIM(结构反应注射成型),SMC(片材成型)等,可以清楚地认识到 RTM 作为新一代复合材料加工工艺在航空、航天、航海、汽车和建筑等各个领域的发展潜力。     

复合材料液体模塑成型工艺与装备进展

本文介绍了复合材料液体模塑成型技术(LCM)的发展历程,对发展过程中出现的一些具有代表性的工艺方法,包括树脂传递模塑(RTM)、真空辅助树脂传递模塑(VARTM)、树脂浸渍模塑(SCRIMP)、树脂膜渗透(RFI)、结构反应注射模塑(SRIM)和脉动灌注(PP)等的技术特点、研发现状及装备发展进行了回顾和总结。并对液体模塑成型工艺的发展趋势进行了展望,认为复合材料液体模塑成型工艺未来将向整体化、自动化、数字化和智能化的方向发展。     

真空灌注低成本成型工艺及其应用研究

介绍了复合材料低成本制造工艺——真空辅助灌注成型技术的基本原理、主要工艺流程，详细阐述其工艺优点，针对国内外真空辅助灌注成型技术进行研究和应用状况概述，并介绍了真空辅助灌注成型在航空航天、船舶制造等领域中的应用。     

复合材料RTM成型工艺综述

本文主要是综述RTM成型工艺的基本原理、工艺特点,讨论了适于RTM的增强材料和树脂休系并讨论了工艺参数对RTM模制品质量的影响以及RTM在成型三维复合材料方面的应用。     

Low temperature cure of vinyl ester resins

Vinyl ester resins are well known for their versatility as a composite matrix. With the development of a promising room temperature molding technology, vacuum-assisted resin transfer molding, e.g. Seemann Composite Resin Infusion Molding Process (SCRIMP), the processability of vinyl ester resins at low temperatures has attracted considerable attention from the composite industry. The objective of this paper is to provide a better understanding of the reaction kinetics of this resin system at low temperatures. In this study, a differential scanning calorimeter (DSC) coupled with a Fourier transform infrared (FTIR) spectrometer was employed to measure the reaction profile of a vinyl ester resin with different promoter and styrene contents. A kinetic model based on the free radical co-polymerization mechanism was developed for simulating the reaction rates and conversions of styrene vinyl and vinyl ester vinylene groups. The model parameters were determined from several FTIR experiments under isothermal conditions. This model, in conjunction with heat transfer analysis, was able to successfully predict the temperature profiles during curing in two SCRIMP molding cases based on groove type resin distribution system.     

兆瓦级风力发电机叶片用环氧树脂

针对兆瓦级风机叶片用纤维/环氧复合材料的特殊要求,开展了适用于真空辅助灌注(VARTM)工艺的环氧基体树脂的国产化研究。采用国产环氧树脂与实验室自制的稀释剂制备环氧树脂与胺类固化剂配合使用,通过示差扫描量热分析,IR光谱,力学性能,耐热性、粘度及吸水性测试等研究了环氧树脂与固化剂配比对其工艺和固化物性能的影响,获得了初始粘度低、粘度对温度不敏感、操作时间长的环氧基体树脂,其树脂浇注体的拉伸性能、弯曲性能均优于国外环氧树脂固化体系,可满足兆瓦级风机叶片用高性能复合材料的使用需求。     

Effect of dual-initiator on low temperature curing of unsaturated polyester resins

In low temperature composite manufacturing processes, a major concern is how to control the resin gel time and cure time and how to achieve a high resin conversion with low residual volatile organic chemicals. In this study, a cobalt promoter catalyzed dual-initiator system was used to control the reaction rate and resin conversion of unsaturated polyester resins. A mechanistic kinetic model was developed to predict the reaction kinetics with dual initiators. This model can be used to simulate the isothermal and dynamic reaction rate and conversion profiles. It can also be utilized to predict the effect of promoter concentration on UP resin cured at low temperatures. The dual-initiator system was applied in the vacuum-assisted resin transfer molding process at room temperature. The kinetic model, in conjunction with the heat transfer analysis, was able to successfully predict the temperature profiles during the molding processes.     

Fire retardancy of a buckypaper membrane

A carbon nanotube membrane (buckypaper) was incorporated onto the surface of a Polyhedral Oligomeric Silsesquioxanes /glass fiber composite by vacuum-assisted resin transfer molding to improve the flame retardancy. The flammability was investigated with a cone calorimeter. With buckypaper on the surface, the heat release rate, peak heat release rate, smoke production rate and CO yield of the composite were decreased dramatically during the combustion.     

气囊辅助RTM工艺用复合裙模具的设计与制备

针对某型号上用VARTM工艺制造的复合裙纤维体积含量偏低的缺点,提出用气囊辅助RTM工艺制造该复合裙。该工艺通过向气囊内充压,对预成型体施加一定的成型压力,从而提高构件纤维体积含量及力学性能。本文设计制备了气囊辅助RTM工艺用复合裙模具。工艺实验表明,借助该模具能顺利实施气囊辅助RTM工艺,制备出高性能的复合裙。     

Tow impregnation during resin transfer molding of bi-directional nonwoven fabrics

A model has been developed for analyzing resin impregnation of fiber tows during resin transfer molding of bi-directional nonwoven fiber performs. The model is based on the existence of two main regions of resin flow: the macropore space formed among fiber tows and the micropore space formed among individual fiber filaments within a tow. The large difference in permeability between these two regions of flow leads to the potential for void formation during resin transfer molding. The model was formulated for both constant flow rate and constant pressure mold filling. For ambient pressure mold filling, the model predicts a difference in the size of the voids and distribution between axial tows (oriented along the flow direction) and transverse tows (oriented in the transverse direction). When vacuum is imposed on the mold, the model predicts the same resin impregnation behavior for both axial and transverse tows. Furthermore, given sufficient time, voids generated under vacuum mold filling will eventually collapse because of the absence of an opposing internal void pressure. In addition to insights on void formation, the model also provides a basis for the study of the relationship between resin transfer molding parameters and the resin impregnation process.     

Preparation and properties of nanoparticle and long-fiber-reinforced unsaturated polyester composites

In this study, a new approach was used to prepare polymer composites reinforced by both nanoparticles and continuous fibers. Carbon nanofibers were prebound onto glass fiber mats, and then unsaturated polyester composites were prepared by vacuum-assisted resin transfer molding. Mechanical and thermal properties of these composites were measured and compared with those of the composites synthesized by premixing carbon nanofibers with the polymer resin. Flexural strength and modulus of composites improved with the incorporation of nanoparticles. Specifically, the property improvement was higher in the case of the composites prepared by the new prebound method. It was also found that carbon nanofibers increased the glass transition temperature and reduced the thermal expansion coefficient of unsaturated polyester composites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

真空辅助RTM用环氧树脂成型工艺研究

对环氧树脂LT-5078体系进行了粘度-温度、粘度-时间测试,研究了其粘度特性,通过动态DSC法测定了树脂的固化反应热,并通过外推法得到其特征固化温度和成型工艺条件。实验表明,LT-5078的凝胶温度、固化温度、后处理温度分别为42℃、102℃、185℃,固化工艺为25℃×24 h+120℃×4 h。该树脂25℃时由初始粘度250 mPa.s上升到800 mPa.s所用时间为170 min左右,常温下有较长的低粘度时长,适合真空辅助RTM成型。     

Improved thermal conductivity for chemically functionalized exfoliated graphite/epoxy composites

Chemically functionalized exfoliated graphite-filled epoxy composites were prepared with load levels from 2% to 20% by weight. The viscosities of the composites having load levels >4% by weight were over the processing window for the vacuum-assisted resin transfer molding process. Wide-angle X-ray diffraction revealed a rhombohedral carbon structure in the filler. Enhanced interaction between the epoxy and the graphite filler was evidenced by an improvement in the rubber modulus for the chemically functionalized graphite/epoxy composites. The thermal and electrical properties of the nanoparticle-filled epoxy composites were measured. The electrical property of the chemically functionalized graphite/epoxy composite deteriorated. Thermal conductivity of the chemically functionalized graphite/epoxy composite, however, increased by 28-fold over the pure epoxy resin at the 20% by-weight load level, increasing from 0.2 to 5.8 W/m K.     

Effects of a chelating agent - 2,4-pentanedione on low temperature composite molding of vinyl ester and unsaturated polyester resins

A major concern in low temperature composite manufacturing processes is how to design and control the mold filling and curing time. Inhibitors or retarders are often used to prevent premature gelation and provide a sufficiently long time to fill the mold completely. However, the addition of these chemical species tends to result in a low mold curing rate and a low final resin conversion. In this study, a chelating agent 2,4-pentanedione (2,4-P) was used to manipulate resin gelation and curing. This agent is known to affect the catalytic activity of the promoters (i.e. metal compounds such as cobalt carboxylates) in the decomposition of initiators. It can function as either a retarder or a co-promoter in the co-polymerization of styrene/polyester and styrene/vinyl ester resins depending on the acidity of the resin system. Based on this observation, an improved room temperature vacuum-assisted resin transfer molding process was designed. This design allows 2,4-P to serve first as a retarder during mold filling to achieve a long gel time, it then as a co-promoter during curing to increase the curing rate. The 2,4-P also increases the resin conversion as the acidity of the resin increases.