改性环氧树脂体系固化动力学及实际固化工艺的研究

主要采用差示扫描量热分析法研究了一种改性环氧树脂基体的固化反应动力学.利用Kissinger-Ozawa方程进行数据处理,获得其固化反应动力学参数,建立了该改性树脂的固化动力学模型.研究结果表明:该固化体系的表观活化能AE=150.56 kJ/mol,反应能级n ≈ 0.95,固化参考温度在177℃左右,并根据此参数研...     

水溶性丙烯酸酯树脂热固化反应研究

用动力学扭辫分析(TBA)法研究了水溶性丙烯酸酯树脂与六甲氧基甲基三聚氰胺的固化反应。实验证明,仅含羧基或羟基的树脂,其固化反应是一步完成的,所得力学阻尼-温度曲线中只出现一个内耗峰;而既含羧基又含羟基的树脂,其固化反应分二步进行,在该曲线中出现两个对应的峰。同时,也用DSC法研究了丙烯酸树脂的热固化反应,得到与TBA法一致的结论。     

芳基乙炔树脂的固化反应动力学及流变行为研究

通过对芳基乙炔树脂的固化动力学研究确定其适宜的固化工艺。采用DSC和流变分析得到芳基乙炔树脂的特征固化参数及其固化度与温度的关系曲线。结果表明,树脂的起始反应温度为127.1℃,反应峰值温度164.2℃,终止反应温度195.1℃。固化动力学参数为:表观活化能E=190.12kJ/mol,反应级数n=1.87,频率因子A=1.995×1019。芳基乙炔树脂的加压固化温度为110～115℃,其起始固化温度为115℃。固化工艺为:115℃/8h+120℃/8h+140℃/2h+160℃/2h+180℃/2h+200℃/2h+220℃/4h。芳基乙炔树脂凝胶前固化过程由化学反应控制,凝胶后属于扩散控制,因此在凝胶时需延长固化时间。     

改性双马来酰亚胺树脂体系固化反应动力学参数的测定

用PERKIN—ELMER公司的DSC—7仪器测定了改性双马来酰亚胺树脂体系的固化反应。根据DSC测试原理和Arrhenius公式建立的固化反应动力学方程,借助DSC—7动力学软件,求出该树脂体系的固化反应动力学参数—Ea、n、z。利用已得到的动力学参数,进一步预测其固化反应程度(a)、固化反应温度(T)和固化反应时间(t)三者之间的关系。并求出该体系的凝胶化温度(Tgel)、固化温度(Tcure)和后处理温度(Ttreat)的近似数值。     

改性双马来酰亚胺树脂固化反应动力学的研究

用 PE DSC-7仪器测定了 N,N,N′,N′—四烯丙基二苯甲烷二胺改性双马来酰亚胺树脂的比热容,并借助DSC-7动力学软件得到该树脂的固化反应级数n=1.39±0.10、反应活化能E_a=138±7.77kJ/mol和表观频率因子InZ=28.6±1.921/sec;还预测了树脂的固化反应程度(d),固化反应温度(T)和固化反应时间 (t)三者间相互关系,并计算了凝胶化温度(Tgel)、固化温度(Tcure)和后处理温度(Ttreat)。     

BMI-5100双马来酰亚胺树脂的固化动力学研究

采用示差扫描量热法(DSC)研究了BMI-5100双马来酰亚胺树脂及其加入质量分数5％的双叔丁基过氧异丙基苯(BIBP)固化剂体系的固化反应动力学.通过线性拟合得到BMI-5100树脂体系的特征温度及固化动力学参数.结果表明:纯BMI-5100的非等温固化DSC曲线呈现单峰反应,其凝胶温度、固化温度和后处理温度分别为2...     

DSC法研究不饱和聚酯树脂的固化反应动力学及其固化过程

采用示差扫描量热法（DSC）分别研究了Ashland UP（R36）以及DSMUP（972B）这两种不饱和聚酯树脂（UP）的固化过程,并利用了KiSSinger方程、Crane经验方程等分析了这两种树脂的固化反应,得到了其固化反应的表观活化能、Arrhenius指前因子（频率因子）、反应级数等动力学参数,最后利用Y—B外推法确定了这两种不同树脂的凝胶温度、固化温度和后固化温度等固化工艺温度。     

刺五加药渣碱法木质素酚醛树脂固化动力学研究

以刺五加药渣为原料,通过碱法得到刺五加药渣碱法木质素并进行羟甲基化改性,与酚醛树脂按比例混合常温搅拌,得到木质素酚醛树脂。采用差示扫描量热法对木质素酚醛树脂固化动力学进行研究,其固化反应的表观活化能为134.6,反应级数为0.95,固化反应的To、Tp和Tf值分别为99.5℃、121.5℃和141.5℃。木质素酚醛树脂固化后,红外谱图l210～l240cm-1,l020~l032cm-1处的吸收峰强度均降低,说明木质素酚醛树脂固化反应主要有两个途径:羟基之间的缩合反应;芳环上活泼氢与羟基之间缩合反应。     

动态DSC法研究BMI改性酚醛树脂固化反应动力学

采用非等温DSC(差示扫描量热)法研究BMI(双马来酰亚胺)改性PF(酚醛树脂)体系的固化动力学,借助升温速率-温度(β-T)外推法和红外光谱(FT-IR)跟踪固化反应过程,确定了BAN(BMI改性PF)体系的固化工艺和固化动力学参数。结果表明:BAN的固化工艺为"120℃/2 h→140℃/2 h→160℃/2 h→180℃/2 h",后处理工艺为220℃/3 h,BAN固化体系的动力学参数是表观活化能Ea=123.4 kJ/mol、频率因子A=1.96×1012s-1和反应级数n=1.05;根据n级动力学反应模型求解出该树脂的反应动力学方程,其计算值与试验值基本吻合,说明该模型能较好描述BAN的固化反应过程。     

双酚A二烯丙基醚/双马来酰亚胺树脂固化动力学研究

以BBE(双酚A二烯丙基醚)作为BDM(4,4′-二氨基二苯甲烷双马来酰亚胺)树脂的改性剂,采用旋转黏度计和非等温DSC(差示扫描量热)法分别研究了BBE/BDM树脂体系在不同温度时的黏度和固化反应动力学过程。研究结果表明:该树脂体系在90~215℃范围内具有较低的黏度(低于1 000 mPa·s),完全满足RTM(树脂传递模塑)的工艺要求;该树脂体系的凝胶温度为210.7℃、固化温度为254.7℃和后处理温度为287.7℃,其固化体系的表观活化能为209.79 kJ/mol、频率因子为3.23×1018s-1和反应级数为0.955(近似1级反应)。     

Cure behaviour of epoxy resin matrices for carbon fibre composites

The cure behaviour of two resin formulations (with high and low curing agent content respectively) of an epoxy resin system, used as matrix for carbon fibre composites, was studied through calorimetric analysis. The aim of this work is to investigate the kinetics of this specific epoxy system in order to be able to choose a proper set of processing parameters which will give good composite material properties. The shape of the conversion curves gives evidence of the differences in the cure kinetics of the two systems. Furthermore, the values of the activation energies were determined both for formulation in the conversion range where vitrification occurs, following a phenomenological approach. These values give an indication of the differences in the curing mechanisms, when varying the content of curing agent. In particular, for both systems, the same reaction represents the onset of the cure process, ie the autocatalytic epoxy ring opening through addition reaction to the primary amine. This reaction dominates the entire cure process of the epoxy formulation at high curing agent content. Conversely, in the formulations with a low curing agent content, after depletion of the primary amines, different reactions may take place (with secondary amines and hydroxyl groups), depending on the cure temperature and the resin viscosity. © 1999 Society of Chemical Industry     

Cure kinetics of epoxy resin used for advanced composites

The cure kinetics of an epoxy resin used for the preparation of advanced polymeric composite structures was studied by isothermal differential scanning calorimetry (DSC). A series of isothermal DSC runs provided information about the kinetics of cure over a wide temperature range. According to the heat evolution behavior during the curing process, several influencing factors of isothermal curing reactions were evaluated. The results showed that the isothermal kinetic reaction of this epoxy resin followed an autocatalytic kinetic mechanism. In the latter reaction stage, the curing reaction became controlled mainly by diffusion. Cure rate was then modeled using a modified Kamal autocatalytic model that accounts for the shift from a chemically controlled reaction to a diffusion‐controlled reaction. The model parameters were determined by a nonlinear multiple regression method. Copyright © 2004 Society of Chemical Industry     

Differential Scanning Calorimetry Cure Studies of Tetra-N-glycidyldiaminodiphenylmethane Epoxy Resins 3 - Reaction with Dicyandiamide

Continuation of work on the curing characteristics of an epoxy resin which is widely used as a composite matrix is reported. Results are given of study of the cure of the resin with dicyandiamide as hardener and diuron as accelerator, using differential scanning calorimetry to monitor the cure. The effect of diuron on the cure of the resin with an aromatic amine curing agent is also described. Distinctive effects of composition are found and values of the apparent activation energy of the curing reaction are derived.     

Cure kinetics of biphenyl epoxy resin system using latent catalysts

The investigation of the cure kinetics of a biphenyl epoxy–phenol resin system with different kinds of latent catalysts was performed by differential scanning calorimetry using an isothermal approach. All kinetic parameters of the curing reaction including the reaction order, activation energy, and rate constant were calculated and reported. The results indicated that the curing reaction of the biphenyl epoxy resin system in this experiment proceeded through an autocatalytic kinetic mechanism, irrespective of the kind of catalyst. The epoxy resin system with acid/diazabicycloundecene (DBU) salt as the latent catalyst showed a second overall reaction order; however, a third reaction order was represented for microencapsulated triphenylphosphine (TPP). The storage stability tests for these systems were performed, and a good shelf life was observed in the epoxy resin system with pyromellitic acid/DBU salt, trimellitic acid/DBU salt, and microencapsulated TPP as the latent catalyst. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2711–2720, 2001     

Cure characterization of Cycom 977‐2A carbon/epoxy composites for quickstep processing

In this effort, Quickstep, a relatively a new technique, have been employed for manufacturing of composite materials. The cure schedule provided by a prepreg manufacturer is usually designed for autoclave or other traditional processing techniques and thermosetting resin systems are formulated for ramp rate curing 2–3 K min^?1. While in case of Quickstep processing, ramp rates of 15 K min^?1 can be achieved, thus changing the chemorheology of resin. The cure process of 977‐2A carbon/epoxy composites was evaluated for Quickstep processing using differential scanning calorimetry (DSC), dynamic mechanical and thermal analysis, and Fourier transformed infrared and results were compared with cure cycle employed for autoclave curing. Optimum hold time for Quickstep processing at upper curing temperature (180°C) was determined using DSC. The hold time of 120 min at 180°C was found to be suitable for Quickstep cure cycle, producing a panel of similar degree of cure to that achieved through autoclave processing schedule. Final degree of cure was dependent on time spent at upper cure temperature and slightly on initial steps of the cure cycle which was used to control the resin flow, fiber wetting, and void removal. Quickstep processed samples exhibited higher T_g and crosslink density and similar molecular network structure to the autoclave cured samples. POLYM. ENG. SCI., 54:887–898, 2014. © 2013 Society of Plastics Engineers     

二氧化硅粉体改性E—Si／CE固化动力学的研究

采用非等温差示扫描量热法（DSC）研究了纳米二氧化硅（SiO2）和微米SiO2的混合粉体改性环氧基硅烷（E—Si）／氰酸酯（CE）树脂体系固化动力学;用Kissinger、Crane和Ozawa法确定固化动力学参数。结果表明,Kissinger式求得的表观活化能为66．09kJ／mol;Ozawa法求得的表观活化能为7001kJ／mol;根据Crane理论计算该体系的固化反应级数为0.89。计算了不同升温速率所对应的不同温度的频率因子和反应速率常数;求得了改性体系的固化工艺参数：凝胶温度130．74℃、固化温度160．96℃和后处理温度199.16℃,确定了体系的最佳固化工艺。与E—Si／CE体系对比表明,SiO2的加入可以降低E—Si／CE体系的活化能,使其固化能在较低温度下进行。     

低温固化改性BMI树脂基体动力学研究

采用催化剂、3,3′-二烯丙基双酚A(DP)和多官能团单体C改性4,4′-二氨基二苯甲烷双马来酰亚胺(BMI)树脂,制取低温固化、高温性能优良的改性BMI树脂。采用差示扫描量热法(DSC)研究了改性BMI树脂的固化反应动力学,计算了固化反应体系的动力学参数,进而提出了该改性BMI树脂固化成型过程的动力学模型,并结合傅里叶红外光谱(FT-IR)对反应机理进行了探讨。研究结果表明,催化剂对固化反应的进行有重要的促进作用,改性BMI树脂的固化温度由259℃降为178℃;烯丙基与马来酰亚胺基的"ene"反应非常显著,且改性剂C与DP的"ene"反应历程相似;改性BMI树脂的固化工艺确定为120℃×6h+140℃×2h+160℃×2h+180℃×2h,后处理工艺为200℃×6h。     

Torsional braid analysis of the cure of some tetra-N-glycidyl-4,4′-diaminodiphenylmethane systems

Torsional braid analysis has been used to study the curing reaction of some resin systems based upon tetraglycidyldiaminodiphenylmethane. TBA gives isothermal times to gelation and vitrification and hence the processing window for the particular systems studied at any intermediate isothermal temperature. The activation energies for the processes involved were also derived allowing extrapolation outside the range of the experiments.     

APG工艺用环氧树脂体系的固化及流变模型

研究了自动压力凝胶工艺用环氧树脂混合体系在动态升温过程中的固化反应,采用Malek法确定了动力学模型并预测了相应的参数。该体系符合两参数自催化SB模型。用旋转流变仪测定了该体系在动态升温过程中黏度相对于温度的变化曲线,采用WLF和Macosko混合方程描述该体系的化学流变模型,用非线性拟合方法预测了模型中的参数。模型预测与实验数据比较吻合。     

有机硅改性AS—70环氧树脂固化反应的研究

本文报道用差示扫描量热法（DSC）研究自制的有机硅改性AS—70环氧树脂固化反应的结果．讨论该树脂与几种常用固化剂固化反应的温度，反应热和反应活化能及在一定温度下固化反应的速率．