树脂膜熔渗工艺浸渍过程的模拟与分析

针对树脂膜熔渗(RFI)成型工艺过程中充模阶段树脂在预制件中的流动行为进行分析,根据牛顿流体在多孔介质中的渗流理论,在Darcy定律基础上使用有限元控制体技术建立二维等温流动控制方程,再对试验件进行几何建模和网格剖分,使用C++语言编写模拟成型工艺中树脂流动过程的程序。由计算实例可见,该方法能够很好地预测树脂浸渍过程中浸渍时间与预浸高度的关系,并确定流动前沿及模腔中的压力的变化规律。     

Analysis of Transversal Permeability for Different Types of Glass Fiber Reinforcement

In some of the new processes to produce elements in composite materials, the innovation is due to the fact that the resin flow is perpendicular to the plane of the reinforcement during the impregnation.So a very important parameter is the transversal permeability of the reinforcing materials used in these processes. In fact for a high value of this parameter it is possible to increase the product quality and to reduce the process time.In this work, using Darcy's law and a particular permeameter, the transversal permeability of preforms constituted by fabric and mat layers of fiber glass has been valued for different injection pressures. In particular, the permeability of two types of preform, consisting respectively of only mat layers and of only fabric layers, have been determined by tests and calculated by Kozeny–Carman equation. The research has been also focalised on the evaluation of the permeability of preforms constituted by a mix of the two different types of reinforcement. Furthermore an analytical model has been studied to calculate the permeability of preforms consisting of layers of different reinforcement types, starting from the permeability data characterizing the single reinforcement type and determined by the tests or by Kozeny–Carman equation.     

复合材料RFI成形的树脂膜揭取性研究

采用树脂膜/离型纸的T型剥离实验方法来表征RFI树脂膜操作过程中的揭取特性,实验研究了几种基本RFI树脂膜的T形剥离载荷-位移关系在不同加载速度及不同实验温度下的表现形式.结果显示内聚破坏与界面破坏情况下载荷位移曲线有明显不同的形式.提高温度有利于出现内聚破坏,而提高实验速度则易于出现界面破坏.进一步从实验数据总结出树脂膜揭取的工艺范围应当在出现界面破坏的温度范围内.     

复合材料RFI成形用树脂膜的成膜工艺性研究

针对先进复合材料树脂膜渗透成形技术(RFI)中的树脂膜,分析了其成形的基本过程,在测定树脂体系的基本粘度-温度关系基础上,采用树脂膜/离型纸的拉伸剪切实验方法测定了树脂膜的拉伸剪切强度,研究了树脂膜在不同温度及速度下的剪切载荷-位移关系及内聚破坏及界面破坏的转变温度范围.结果显示,破坏形式的转化是决定剪切强度-温度依赖性的关键.确定了实验树脂体系的成膜工艺区间的下限.     

RFI成型工艺的数值模拟研究进展

综述了树脂膜熔渗(RFI)成型工艺数值模拟所依赖的数学模型以及核心算法的研究进展,着重总结了树脂的流动、抑制孔隙产生、热传递以及固化动力学等方面数学模型的研究进展.对这些模型的研究有利于更加深入地理解成型工艺中复杂的物理和化学变化,通过数值模拟可以预测工艺参数,从而优化整个工艺过程、缩短研发周期.     

不饱和聚酯树脂体系化学流变特性研究

采用DSC热分析技术和黏度实验方法,研究LSP-8020B不饱和聚酯树脂体系的固化特性和化学流变特性,建立与实验数据较为吻合的工程黏度流变模型.模型可揭示树脂体系在不同工艺条件下的黏度变化规律,定量预报树脂体系的低黏度平台工艺窗口,为该树脂体系真空导入模塑工艺参数优化和保证大型复合材料构件整体成型质量提供一定的科学依据.     

由液化物树脂制备多孔碳纳米纤维及其表征

以壳粉为原料,在碱性条件下制备液化物树脂(LPF),经静电纺丝、固化、碳化得到多孔碳纳米纤维(PCNF)。探讨了聚乙烯醇(PVA)用量对纺丝液特性及纤维形貌的影响。同时,采用傅里叶变换红外光谱(FTIR)、热重分析仪(TG)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、全自动比表面积及孔隙分析仪(BET)等方法对不同碳化温度下的样品进行表征。结果表明:少量PVA可以明显提高LPF的纺丝性,且随PVA用量的增加,纤维的形貌更规整、直径更小;随着碳化温度的升高,LPF/PVA纤维逐渐裂解,多数官能团消失,基体为多苯稠环结构;同时,层间距d_((002))逐渐减小,平面尺寸L_c和L_c/d_((002))增加,纤维内部的类石墨结构逐渐向更规整、有序的石墨微晶结构转变;当碳化温度为800℃时,LPF/PVA的含碳量达55%以上,随着PVA用量的增加,纤维的比表面积明显增大且多以微孔为主,当PVA用量为8%时,得到比表面积为590m~2/g的多孔碳纳米纤维。     

丙烯酸系高吸水性树脂多孔结构的形成和控制

采用反相悬浮聚合法制备多孔AA-AANa-AM共聚物微球。经FT-IR、SEM、EDS等手段对微球组成、结构与微区进行分析,认为:通过对AA-AANa-AM共聚物组成的设计,可有效控制高吸水性树脂(SAR)微球的成孔情况;随PAM含量增多,微球内孔数增加,孔径略有增加,当AM与AA比值为1/2时,所制得SAR微球的成孔情况最佳;微球所形成的多孔结构均为连通开孔结构。探索微球成孔机理,认为树脂组成上的差异和外界的诱导作用是孔洞形成的原因。经检测,微球吸水倍率为1150 g/g,吸100倍水最快只需15 s。     

Exothermic Temperature History in the Processing of Resin Infused Composite Structural Components

Resin Infusion Processes such as SCRIMP, VA-RTM, and variations thereof, are increasingly being considered for the fabrication of large structural components such as bridge decks and ship hulls wherein preform elements consist not only of varying fabric architectures but also include foam cores. Based on the method of infusion – high permeability distribution media or resin channels/microgrooves, flow through the preform can be tailored to be either 1-D, 2-D, 3-D or a combination thereof. This paper emphasizes the effect of exothermic temperature history on flow & cure phenomena, and mechanical properties of a series of structural elements ranging from a flat plate to a typical truss-core type structure. The effect of geometry and flow on exothermic characteristics is experimentally monitored, and results correlated to provide guidance in the further use of the process. Critical areas lacking in detailed understanding are identified and a set of preforming and process induced defects that cause changes in thermal history are described.     

热固性硅树脂压注法制备多孔硅基陶瓷型芯研究

以石英玻璃粉为基体, 热固性硅树脂为增塑剂, 利用压注方法制备了多孔硅基陶瓷型芯, 研究了烧结温度和保温时间对样品性能的影响。研究结果表明: 随着烧结温度的升高, 反玻璃化进程加快, 在烧结温度1250℃, 随着保温时间的延长, 玻璃相发生了转变, 逐渐析出方石英, 且含量不断增加; 样品的线收缩率和失重随烧结温度的升高略微增加, 但烧结时间的影响较小。样品的失重主要是由于硅树脂的分解引起的。在1250℃烧结10 h后, 得到样品的收缩率为0.93%, 显气孔率为32.8%, 抗弯强度为9.08 MPa。     

Porous Media Analysis by Modified MLPG Formulations

This work proposes a modified procedure, based on analytical integrations, to analyse poroelastic models discretized by time-domain Meshless Local Petrov-Galerkin formulations. In this context, Taylor series expansions of the incognita fields are considered, and the related integrals of the meshless formulations are solved analytically, rendering a so called modified methodology. The work is based on the u-p formulation and the incognita fields of the coupled analysis in focus are the solid skeleton displacements and the interstitial fluid pore pressures. Independent spatial discretization is considered for each phase of the model, rendering a more flexible and efficient methodology. The Moving Least Squares approximation is employed for the spatial variation of the displacement and pore-pressure fields and two variants of the meshless local Petrov-Galerkin formulation are discussed here, which are based on the use of Heaviside or Gaussian weight test functions. Modified expressions to properly compute the shape function derivatives are also considered. At the end of the paper, numerical examples illustrate the performance and potentialities of the proposed techniques.     

己二酸/酚醛树脂共聚炭化制备多孔炭材料及其电性能研究

以酚醛树脂(PF)为炭前驱体, 己二酸(DA)为致孔链段, 利用聚合物共聚炭化法制备双电层电容器用多孔炭材料. 通过红外和热重分析证实己二酸与酚醛树脂发生了化学反应, DA以链段或支链的形式存在于酚醛树脂固化体系中, 并在后续炭化过程中热解逸出. 氮气吸附分析表明酚醛树脂固化体系中的DA起到了一定的造孔作用, 随着DA加入量增加, 多孔炭比表面积先增大后减小, 当w(PF)/w(DA)=3:1时所得多孔炭的比表面积为550 cm²/g, 孔容为0.27 cm³/g. 采用直流充放电法、交流阻抗法和循环伏安法测定以上述多孔炭为电极材料的双电层电容器的电化学性能, 结果表明: w(PF)/w(DA)=3:1时制得的多孔炭电极在30% KOH电解液中比电容为145 F/g, 电流密度增大50倍, 比电容保持率达到70 %.     

热塑性树脂增韧酚醛树脂基复合材料研究

研究热塑性树脂的含量、端基、分子量对酚醛树脂基复合材料性能的影响，用扫描电镜观察增韧体系的断口形貌，对增韧机理进行了探索。结果表明，以热塑性树脂膜和固化后的酚醛树脂膜形成连续相、酚醛树脂固化球粒为分散相的“网膜-球粒”结构使酚醛树脂基复合材料的韧性提高。     

树脂基复合材料关键制造技术的研究进展与制约因素分析

详细介绍了树脂基复合材料的关键制造技术——成型工艺技术、固化工艺技术及连接工艺技术的特点、适用范围、国内外研究进展及我国与国外的差距,重点分析了我国树脂基复合材料发展的主要制约因素,并提出了促进复合材料产业快速发展的研究建议。     

水溶性环氧树脂对注凝成型Al2O3泡沫陶瓷结构和性能的影响

以异丁烯和马来酸酐共聚物(PIBM)为分散剂和凝胶剂, 同时添加两种表面活性剂, 通过机械发泡和注凝成型工艺制备高气孔率Al₂O₃泡沫陶瓷, 并研究了DE211环氧树脂对Al₂O₃泡沫陶瓷结构和性能的影响。结果表明, 该工艺能够制备气孔率达92.4%的Al₂O₃泡沫陶瓷。随着DE211环氧树脂的加入, 泡沫陶瓷的气孔率略有降低, 抗压强度由0.5 MPa提高到3 MPa, 平均气孔尺寸由582 μm下降到331 μm, 孔壁塌陷少。这归因于DE211环氧树脂的环氧基能够与PIBM的酸酐发生反应, 加快凝胶固化速度, 从而有利于稳定泡沫结构。     

RTM用双马来酰亚胺树脂流变特性研究

树脂粘度对于树脂传递模塑成型工艺而言是必要的参数之一。本工作对一种RTM用双马来酰亚胺树脂的流变特性进行较为系统的研究，并根据双阿罗尼乌斯方程，建立了与实验数据较为相符的化学流变模型，同时对该树脂进行牯彦预测．为确审该树脂的RTM工艺窗口提供了可靠的理论依据。     

用于CIRTM工艺的环氧树脂酚醛树脂的固化工艺研究

采用动态差示扫描量热(DSC)法,研究了用于CIRTM工艺的E-44/GA327(DDM改性芳胺)环氧体系和苯并噁嗪酚醛树脂的固化过程,以及升温速率对固化体系DSC曲线的影响,并采用最佳固化温度外推法确定了两种树脂的最佳共固化制度。结果表明,苯并噁嗪固化反应表观活化能Ea为70.35kJ/mol,表观指前因子A为1.27×107s-1,反应级数n为0.897;E-44/GA327体系固化反应表观活化能Ea为44.04kJ/mol,表观指前因子A为1.78×104s-1,反应级数n为0.884。两种树脂的最佳共固化制度为140℃/240min+180℃/240min,按所确定的共注射树脂的固化工艺制备了浇铸体,苯并噁嗪和E-44/GA327的固化度分别达到了96.7%和98.3%,固化物力学性能良好,验证了固化工艺的合理性。     

硼酚醛-环氧树脂体系固化过程分析

采用Friedman法求解了硼酚醛-环氧树脂体系的固化反应动力学参数及固化机理模型,预测了170℃硼酚醛-环氧树脂体系的等温固化曲线,确定了此体系的等温理论转化率与时间的关系,得到不同时间的理论转化率。并且采用170℃的电热鼓风干燥箱对此体系做等温固化试验,取不同固化时间的试样,用差示扫描量热仪测得树脂的实验转化率,并且与理论值进行比较。结果表明,硼酚醛-环氧树脂体系的固化反应模型属于An型,固化反应机制函数为[-ln(1-α)]1.39=1.80×10-4t,在低固化阶段,理论转化率与实验转化率相接近,但随着固化程度的增加,理论值明显高于试验值。     

Pore‐Scale Flow Characterization of Polymer Solutions in Microfluidic Porous Media

Polymer solutions are frequently used in enhanced oil recovery and groundwater remediation to improve the recovery of trapped nonaqueous fluids. However, applications are limited by an incomplete understanding of the flow in porous media. The tortuous pore structure imposes both shear and extension, which elongates polymers; moreover, the flow is often at large Weissenberg numbers, Wi, at which polymer elasticity in turn strongly alters the flow. This dynamic elongation can even produce flow instabilities with strong spatial and temporal fluctuations despite the low Reynolds number, Re. Unfortunately, macroscopic approaches are limited in their ability to characterize the pore‐scale flow. Thus, understanding how polymer conformations, flow dynamics, and pore geometry together determine these nontrivial flow patterns and impact macroscopic transport remains an outstanding challenge. This review describes how microfluidic tools can shed light on the physics underlying the flow of polymer solutions in porous media at high Wi and low Re. Specifically, microfluidic studies elucidate how steady and unsteady flow behavior depends on pore geometry and solution properties, and how polymer‐induced effects impact nonaqueous fluid recovery. This work thus provides new insights for polymer dynamics, non‐Newtonian fluid mechanics, and applications such as enhanced oil recovery and groundwater remediation.