一维RFI工艺流动模型的建立及数值模拟

在已知叠层结构预制件渗透率的基础上,根据树脂的流动特点,建立一维树脂膜熔渗(RFI)工艺的流动模型,通过数值模拟推导在不同纤维含量预制件中,树脂湿润高度、树脂湿润区域内树脂流动速度和压力分布规律,为设计制件结构尺寸,优化真空袋固化成型工艺参数提供了理论依据。     

单胞法预测玻璃纤维平纹织物的渗透率

运用树脂在纤维束内和纤维束间的耦合流动模型,结合Darcy定律,建立平纹织物的单胞模型,模拟预测单胞Z方向的渗透率,并通过改变单胞厚度尺寸参数研究纤维体积分数与渗透率的关系。结果表明:单胞的渗透率随着纤维体积分数的增加而减小,模拟结果与Kozeny-Carman方程对比,二者偏差很小,且在纤维体积分数52.5%处重合,表明该计算方案是合理的。     

氰酸酯树脂体系的流变特性研究

本文以改性RTM氰酸酯树脂体系流变特性为研究对象,深入研究了树脂体系的流变行为,建立了氰酸酯树脂在恒温和动态条件下的流变特性方程。研究表明,恒温条件和动态条件下的树脂流变行为符合Arrhen ius流变模型,模型计算结果与流变测试结果符合很好。本研究为氰酸酯树脂体系的成型工艺的制定和优化提供有力的依据。     

树脂基复合材料模压工艺加压时机优化研究

本文提出以树脂粘度为依据选择加压时机，针对不同加压时机进行了算例研究。以树脂粘度为控制变量进行加压时机优化，即给定材料体系以及工艺条件，以最终产品的纤维体积分数为目标函数，以粘度为优化变量，确定加压时机的树脂粘度值。     

熔融浸渍工艺参数对纤维束渗透率影响的研究

在连续长纤维增强热塑性复合材料浸渍模型中,渗透率是一个十分重要的参数。准确测量熔融浸渍工艺中高黏度树脂熔体浸润纤维束的渗透率,有助于浸渍模型更好指导熔融浸渍模具设计和工艺参数优化,制备出性能优异的热塑性树脂基复合材料。本文通过自制实验装置,测定了熔融浸渍工艺中高黏度树脂浸渍单向纤维束时纤维束张力和浸渍压力变化对渗透率的影响,根据实验结果拟合出工艺参数与渗透率关系的计算公式。结果表明：纤维束张力越大渗透率越低;浸渍压力越大,纤维束渗透率越大,但增大幅度随张力增大而降低。     

树脂膜熔渗工艺及其数值分析方法

本文首先介绍了树脂膜熔渗RFI成型工艺的发展现状、技术原理、材料要求及工艺特点,然后重点阐述了RFI工艺过程的数值模拟方法,对如何建立能够反映RFI工艺过程中树脂流动、固化和热传递等物理化学现象的数学模型进行了讨论.RFI工艺过程涉及参数较多,单纯采用试验方法来研究各种参数变化带来的影响不仅耗时,而且也不经济,结合数值模拟方法对RFI工艺进行研究,可以减少盲目性和提高效率,从而为优化工艺参数提供理论依据.     

RFI用改性双马树脂膜的黏度特性

采用热塑性树脂改性双马来酰亚胺树脂,获得了适用于RFI成型的改性双马来酰亚胺树脂膜。采用DSC方法和黏度测试研究了该树脂的固化特性和黏度特性,并根据黏度特性建立了Arrhenius模型。结果表明,改性双马来酰亚胺树脂膜的黏度特性能够满足RFI工艺的要求,建立的Arrhenius模型能够较好地预测黏度特性,可为RFI工艺参数的制定提供理论指导。     

VARI制备高长径比复合材料的树脂流动研究

对VARI制备高长径比复合材料过程中的树脂流动行为进行模拟与实验研究,利用PAM-RTM软件模拟树脂流动过程,讨论了各工艺参数对树脂流动的影响,并通过实验测试对模拟结果进行了验证与比较。研究表明,纤维增强体孔隙率越大、注射压力越大和树脂粘度越低,树脂的填充速度越快。在模具直径φ4 mm、注射压力0.3 MPa、树脂粘度≤0.9Pa˙s和纤维体积分数≤60%的情况下,可以实现较长试件的快速注射,所需注胶时间最高不超过2 h。     

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。     

RFI工艺制备复合材料板材研究

利用自制的环氧树脂膜,采用RFI工艺制备了薄平板、曲面板、加筋板、厚平板,初步确定了成型工艺参数并对板材的性能进行了研究。结果表明,自制的环氧树脂膜可用于RFI工艺制备薄平板、曲面板,树脂浸润性良好,纤维体积含量达到了44.8%,力学性能优良;加筋板与厚平板有贫胶现象。     

风机叶片用环氧树脂体系流变性能研究

本文对风机叶片用环氧树脂体系的流变性能进行了研究,在粘度实验的基础上,依据双阿累尼乌斯方程建立了与实验数据较为吻合的流变模型。结果表明,两种树脂体系的粘度随温度变化情况基本一致,在23～50℃范围内,其粘度都低于300mPa.s,且低粘度保持时间大于30min,符合风机叶片真空成型对树脂低粘度的要求。所建立的粘度模型可有效预测和模拟树脂体系在不同工艺条件下的粘度行为,揭示树脂体系的优化工艺参数和低粘度平台工艺窗口,为合理拟订工艺参数和保证产品质量提供必要的科学依据。     

5228环氧树脂体系化学流变特性研究

本文对5228环氧树脂体系的化学流变特性进行研究。采用DSC热分析技术和粘度测量手段,研究该树脂体系固化特性和固化过程中粘度与温度的关系,根据对等温和动态粘度曲线的分析,建立了工程恒温粘度模型,通过积分变换将模型推广到非恒温条件下使用,验证了所建立的粘度模型在工程中的准确性。所建立的工程粘度模型能有效地预测体系热压工艺的粘度变化和工艺窗口,具有工程实用性,为复合材料成型工艺模拟分析及工艺参数的确定奠定了基础。     

Effect of furfuryl alcohol addition on the cure of furfuryl alcohol resin used in the glassy carbon manufacture

Glassy carbon can be manufactured practically without pores, named Monolithic Vitreous Carbon (MVC) or presenting up to 98% in transport pore volume, foam form, denominated Reticulated Vitreous Carbon (RVC). The glassy carbon processing is affected by some processing parameters, among them it can be cited the resin viscosity. The present work involves the optimization of RVC manufacture by monitoring the polyurethane (PU) foam impregnation with furfuryl alcohol resin with different viscosity values, which were obtained by dilution of the resin with different amounts of furfuryl alcohol. The resin samples used in the PU impregnation were characterized by thermal and rheological analyses. These results were correlated with scanning electron microscopy observations and compression test results of the impregnated polyurethane foam. The results show that the rheological behavior of the resin has significant influence on the polymerization step, affecting the homogeneity of impregnated foam and, consequently, its final properties, mainly the mechanical one. The impregnated foam prepared with the furfuryl alcohol resin diluted with 10% of furfuryl alcohol (η = 11.4 Pa s) showed higher compression values (0.26 MPa). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

PP医用输液瓶专用树脂的工业开发

在115kt／a浆液法聚丙烯装置上进行了医用输液瓶专用树脂B205的工艺路线设计及工业开发，根据此专用树脂的物理机械性能、光学性能、卫生指标、外观及加工流变性能等方面的要求，确定了工艺技术方案。B205的熔体流动指数为0．9—1．3g／10min，屈服抽伸强度大于或等于27MPa，冲击强度大于或等于4．5kJ/m^2，符合医药卫生级树脂标准要求。用B205制成的聚丙烯瓶具有机械强度高、透明性好、透水性小、耐蠕变和瓶壁薄的特点。     

Surfactant effect on DLP fabrication of silica fibre preforms

Three-dimensional (3D) printing based on digital light processing (DLP), for its great advantage in dealing with material and structural complexities, is being engaged for the fabrication of custom-designed silica optical fibre preforms. Resin preparation and printing are key processes critical to DLP fabrication of optical fibre preforms with high silica loading. In this work, the surfactant effect on preparation of resin and DLP printing of optical fibre preforms for higher silica loading is investigated. Based on our experimental studies of the rheological and photocuring properties of resins and the quality of printed silica fibre preforms, we find that, in the case where 2-phenoxyethanol (POE) is usually added as the surfactant, the resin has higher viscosity and results in poorer preform quality. By removing POE from resin ingredients and designing a multi-step resin processing with appropriate settling and degassing processes, fibre preforms with high silica loading up to 0.8 (w/w) have been successfully fabricated.     

建立科学的聚氯乙烯性能评价体系

介绍了PVC树脂的质量指标对PVC加工性能的意义。通过对4种国内外不同厂家生产的PVC树脂进行形态结构、物理性能、加工流变性能、力学性能及热性能的对比分析,发现国产PVC树脂质量与国外PVC产品存在明显的差异,并提出了改进PVC树脂性能的方法,为提高我国PVC树脂的质量找到了相关依据。     

两种典型环氧树脂基覆铜板加工工艺的对比研究

采用差示扫描量热仪和旋转流变仪对比研究了双氰胺(DICY)/环氧树脂和酚醛树脂(PN)/环氧树脂两种典型的环氧树脂基覆铜板用环氧树脂体系的固化行为和流变特性,求出了固化动力学参数,同时考察了填料对PN/环氧树脂固化体系流变特性的影响,优化了层压工艺参数.     

Effects of resin storage aging on rheological property and consolidation of composite laminates

The ability to predict the viscosity of thermoset resin is important to understand the manufacturing process of composites and optimize the processing parameters. During resin or prepreg storage course, the cure reaction may happen and the degree of cure increases gradually. The storage aging effect reduces the fluidity of resin, and hence alters the processability of resin. In this article, the rheological properties of an epoxy resin and a bismaleimide resin used in composite autoclave process were measured and a viscosity model was established, which can predict the viscosity progression during cure for different aging degree of resin. Moreover, a computer simulation method was used to study the effects of aging degree on the composite consolidation and the processing operations. It is found that the viscosity model of aged resin can be obtained by modified dual Arrhenius model of fresh resin with the dynamic rheological measurement. The resin aging strongly alters the flowability, so influences composite consolidation. According to the simulated results, the processing parameters need to be adjusted to achieve cured composites with appropriate fiber content. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Analysis of the structure and mass transport properties of clay nanocomposites based on amorphous PET

The aim of this work is to characterize the rheological and permeability behavior of nanocomposites based on amorphous poly(ethylene terephthalate) (PETg) and organically modified montmorillonites (omMMT), obtained by melt intercalation. The use of PETg instead of semicrystalline PET is believed to reduce the risks associated to organic modifier degradation during processing at high temperatures. X‐ray and transmission electron microscopy analysis performed on the PETg nanocomposites showed that processing for long time at temperatures lower than melting of semicrystalline PET allowed to obtain a partially intercalated structure with some degree of exfoliation. The rheological behavior of PETg nanocomposites was studied as a function of shear rate in a cone–plate rheometer in order to correlate the viscosity with the aggregation state of omMMT. A simple model accounting for an apparent increase of rheological units size, associated with the intercalation of PETg macromolecules into omMMT galleries, is proposed. The glass transition temperature, T_g, as a function of the volume fraction of omMMT content of the nanocomposite, was measured using differential scanning calorimetry. Finally, the water vapour permeability of PETg nanocomposites was correlated to the volume fraction of the impermeable inorganic part of the omMMT. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010