基于MF/Malek法的FM94胶黏剂固化反应动力学建模

采用非等温差示扫描量热法(DSC)对环氧树脂FM94胶黏剂的固化动力学进行了研究。基于Model-Free法,分析了不同升温速率下的DSC曲线,解释了FM94胶黏剂的固化机理,求解了反应活化能E值,并通过Malek法确定了固化机理函数为自催化模型。结果表明,采用Model-Free法与Malek法结合获得的自催化模型与实验数据吻合得较好,求解得到的模型在升温速率为2 K/min～10 K/min下能较为准确地描述环氧树脂FM94胶黏剂的固化反应过程。     

环氧树脂/玻璃纤维模压预浸料固化反应动力学研究

采用非等温DSC方法研究了一种模压预浸料（环氧树脂/玻璃纤维）的固化动力学,应用Kissinger和Crane方程拟合求得固化动力学参数,并建立了该预浸料固化动力学唯象模型。通过无转子硫化仪测试预浸料在不同温度下的凝胶时间,通过线性拟合得到固化温度与凝胶时间的函数关系,并对预浸料的固化工艺进行优化。结果表明,通过Kissinger和Crane方法算得该预浸料的固化反应动力学表观活化能为89.9 kJ/mol,指前因子为1.17×10¹¹ min^-1,反应级数为0.93;预浸料在模具温度为150 ℃下预热40 s,环氧树脂具有一定的流动性,并在2 MPa压力下固化300 s,可制备综合性能良好的复合材料制品。     

玻璃纤维对环氧基体预浸料固化特征的影响研究

采用动态差示扫描量热法(DSC)研究了玻璃纤维/环氧树脂预浸料体系的固化过程,考察了玻璃纤维对环氧树脂固化动力学的影响;利用Kissinger法和Crane公式计算了体系的反应活化能、指前因子、反应级数等固化动力学参数。结果表明,玻璃纤维使环氧树脂体系的理论凝胶化温度、固化温度和后处理温度升高;同时,增大了固化反应活化能,而固化反应的反应级数基本不变。说明玻璃纤维使环氧树脂体系固化反应变难,但不改变其固化反应机理。     

CMC/E44/DDM体系固化过程及动力学

采用红外光谱和非等温DSC法研究了羧甲基纤维素(CMC)/E44环氧树脂/4,4'-二氨基二苯基甲烷(DDM)体系的固化过程和动力学.红外光谱研究表明,CMC可促使E44/DDM体系在固化过程中生成更多的聚醚结构.DSC非等温固化反应动力学研究表明,CMC的加入在反应初始阶段降低了E44/DDM体系的反应活化能,促进固化反应的进行.采用等转化率法和自催化模型对固化反应的过程进行研究,建立动力学方程.由Starink等转化率法获得E44/DDM和CMC/E44/DDM体系的活化能随转化率的变化情况.E44/DDM体系的活化能随转化率升高而显著降低;CMC/E44/DDM体系的活化能随转化率升高变化不明显,在相同含量时,相对分子质量高的CMC体系活化能高.采用SB自催化模型研究E44/DDM和CMC/E44/DDM体系的固化过程并获得模型参数.对CMC/E44/DDM体系,SB模型对实验结果拟合较好;对E44/DDM体系,SB模型和实验结果吻合效果较差.由于E44/DDM体系活化能随固化度有显著变化,因此采用改进的变活化能自催化模型描述其实验现象,结果显示该法获得的模型能够较好地描述实验现象.动力学模型的建立能够为工艺参数的选择和工艺窗口优化提供理论依据.     

聚乙二醇接枝改性纳米炭黑对环氧树脂固化过程的影响

采用差示扫描量热法研究了以聚乙二醇(PEG)接枝改性的纳米炭黑(NC)(NC-PEG)为填料对环氧树脂/4,4-二氨基二苯砜非等温固化反应的影响,通过Flynn-Wall-Ozawa法和Malek法确定了固化反应的动力学参数.结果表明:两参数的自催化模型能够很好地描述环氧树脂及其复合材料的固化反应过程,各试样的模型拟合结果与实验数据相吻合.NC-PEG能够促进环氧树脂的固化,使固化活化能降低,其中,NC-PEG用量为3 phr时,活化能最低.     

异佛尔酮二胺/环氧树脂非等温固化动力学研究

采用差示扫描量热法(DSC)对异佛尔酮二胺和环氧树脂体系的固化反应动力学进行了研究。分别通过n级反应法和Málek的最大概然机理函数法确定固化反应机理函数,求出固化反应动力学参数,得到相应的固化反应动力学模型。结果表明,通过Kissinger,Crane方法求解动力学参数所得到的n级反应模型与实验值差别较大;而采用Málek方法判别机理,表明该固化反应按照自催化反应机理进行,由esták-Berggren(S-B)自催化模型计算所得到的曲线与实验得到的数据曲线较吻合,能较好地描述该体系的固化反应过程。     

可降解生物基含酯键环氧树脂的固化动力学研究

采用非等温差示扫描量热(DSC)法研究了可降解生物基含酯键环氧树脂固化动力学,分别建立了n级反应动力学模型、自催化模型以及结合n级反应和自催化模型的分段模型,并将模型预测值与实验数据进行了对比分析。结果表明,n级反应模型与实验曲线的偏差较大,自催化模型与实验曲线变化趋势基本一致,但仍然存在一定偏差,而结合两者的分段模型与实验曲线吻合较好,表明分段模型能更准确地描述该环氧树脂体系的固化反应过程,为其树脂基复合材料固化成型工艺条件优化提供理论指导。     

环氧树脂/对甲基苯基双胍固化反应动力学研究

根据非等温和等温DSC数据,采用等转化率法和模型拟合法对环氧树脂/对甲基苯基双胍体系的固化反应过程进行了研究,分析了固化体系在非等温和等温条件下的固化规律。并通过Malek最大概然函数机理法确定了固化反应机理函数,计算出固化反应动力学模型参数。结果表明,考虑了扩散影响的等温自催化反应速率模型对该体系等温固化过程的预测数据与DSC实验数据吻合得更好。同时,在比较非等温和等温自催化动力学模型的计算值与实验值的基础上,结合活化能随固化度的变化规律,对不同温度条件、不同转化率下固化体系的反应历程和机理进行分析,为工业应用中固化工艺条件的优化提供了理论依据。     

MOCA/环氧树脂等温固化行为研究

用差示扫描量热法对亚甲基双邻氯苯胺(MOCA)/环氧树脂体系的等温固化反应进行了研究。用Kamal自催化模型分析MOCA/环氧树脂体系的等温固化动力学,结果表明,该固化过程具有自催化反应的特征,固化过程符合Kamal自催化模型。采用非模型拟合法中的非线性Vyazov kin(NLV)法计算该体系的活化能。     

非等温DSC法研究苯并恶嗪树脂固化反应动力学

采用非等温DSC法对M型苯并恶嗪(MBOZ)固化动力学进行了研究。分别通过n级反应模型和自催化模型求解出反应动力学参数,进而得到固化反应动力学模型。结果表明,n级反应模型与实验值的差别较大;而采用自催化模型得到的曲线与实验得到的DSC曲线吻合较好,所确立的模型在5～15 K/min的升温速率下能较好地描述MBOZ的固化反应过程,并为其树脂基复合材料工艺优化条件提供了理论依据。     

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     

Resin transfer molding (RTM) process of a high performance epoxy resin. I: Kinetic studies of cure reaction

The cure kinetics of a high performance PR500 epoxy resin in the temperature range of 160–197°C for the resin transfer molding (RTM) process have been investigated. The thermal analysis of the curing kinetics of PR500 resin was carried out by differential scanning calorimetry (DSC), with the ultimate heat of reaction measured in the dynamic mode and the rate of cure reaction and the degree of cure being determined under isothermal conditions. A modified Kamal's kinetic model was adapted to describe the autocatalytic and diffusion‐controlled curing behavior of the resin. A reasonable agreement between the experimental data and the kinetic model has been obtained over the whole processing temperature range, including the mold filling and the final curing stages of the RTM process.     

Study of the effect of BDMA catalyst in the epoxy novolac curing process by isothermal DSC

Epoxy novolac/anhydride cure kinetics has been studied by differential scanning calorimetry under isothermal conditions. The system used in this study was an epoxy novolac resin (DEN431), with nadic methyl anhydride as hardener and benzyldimethylamine as accelerator. Kinetic parameters including the reaction order, activation energy and kinetic rate constants, were investigated. The cure reaction was described with the catalyst concentration, and a normalized kinetic model developed for it. It is shown that the cure reaction is dependent on the cure temperature and catalyst concentration, and that it proceeds through an autocatalytic kinetic mechanism. The curing kinetic constants and the cure activation energies were obtained using the Arrhenius kinetic model. A suggested kinetic model with a diffusion term was successfully used to describe and predict the cure kinetics of epoxy novolac resin compositions as a function of the catalyst content and temperature. Copyright © 2003 Society of Chemical Industry     

A study on the cure characteristics of epoxy/diaminodiphenylmethane system prepared at room temperature

The curing behavior and kinetics of epoxy resin with diaminodiphenylmethane (DDM) as the curing agent was studied by many researchers, however all of them prepared the system at a high‐temperature condition (i.e., T ≥ 80°C). In this study, a mixture of epoxy/DDM was prepared at ambient temperature and its curing characteristics were studied by using differential scanning calorimetry (DSC). The autocatalytic model was used to calculate the kinetic factors in the dynamic experiments. The kinetics of the curing reaction was also evaluated by two different isoconversional models; namely Friedman method and the Advanced Isoconversional method proposed by Vyazovkin to investigate the activation energy behavior during the curing reaction. The activation energy of the curing reaction was found to be in the range of 48 ± 2 kJ/mol and might be considered to be constant during the curing. In fact, our findings were different from the result reported by other researchers for the system which was prepared at elevated temperature. Therefore, it seems that the preparation temperature of the samples influenced considerably on the curing behavior of epoxy with DDM. Finally, a time–temperature–transformation (TTT) diagram was established to determine the cure process and glass transition properties of the system. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Curing kinetics study of an epoxy resin system for T800 carbon fiber filament wound composites by dynamic and isothermal DSC

Curing kinetics of DGEAC/DDM/DETDA/DGEB epoxy resin system was studied using dynamic and isothermal differential scanning calorimetry (DSC) for the preparation of T800 carbon fiber filament wound composites. In dynamic experiment, four kinds of epoxy resin systems were studied. Curing characteristics, such as curing range and curing temperatures of the epoxy resin system with mixed hardeners (DGEAC/DDM/DETDA), were found lying within those of the two epoxy resin systems with a single hardener (DGEAC/DDM, DGEAC/DETDA). The addition of reactive diluter (DGEB) caused increase in curing range and exothermic heat. In addition, the activation energies calculated by the isoconversional method of all four resin systems decreased to the minimum value in the early stage due to the autocatalytic role of hydroxyl groups in the curing reaction and then increased due to the increased viscosity and crosslink of epoxy systems. The addition of reactive diluter led to the decrease in activation energies on the initial stage (conversion = 0.1–0.3). In isothermal experiment, a series of isothermal DSC runs provided information about the curing kinetics of the DGEAC/DDM/DETDA/DGEB system over a wide temperature range. The results showed that the isothermal kinetic reaction of the epoxy resin followed an autocatalytic kinetic mechanism. The autocatalytic kinetic expression chosen in this work was suitable to analyze the curing kinetics of this system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

没食子酸环氧树脂/蓖麻油酸多胺体系固化动力学及性能

以蓖麻油和三乙烯四胺为原料合成蓖麻油酸多胺固化剂（COAPA）,再将其与没食子酸环氧树脂（GAER）混合组成全生物基GAER/COAPA固化体系,采用非等温差示扫描量热法（DSC）对其固化反应过程进行了研究,确定了固化体系最佳质量配比为7∶3（GAER∶COAPA）,获得了最佳固化工艺温度参数;利用Kissinger方程和?esták?Bergg?ren自催化模型拟合得到固化反应活化能和动力学参数,并将固化后的GAER体系与双酚A型环氧树脂体系的性能进行了对比。结果表明,GAER/COAPA体系的平均表观活化能为62.28 kJ/mol,当固化反应转化率（α）小于60 %时符合?esták?Berggren自催化模型;与双酚A型环氧树脂体系相比,GAER/COAPA的热分解温度参数偏低,800 ℃时残炭率较高,拉伸强度和弯曲模量较低、弯曲强度和玻璃化转变温度稍高。     

最概然Malek法分析TDE 85/MeNA环氧树脂体系固化机理

 采用非等温DSC法对三官能团环氧树脂TDE 85与甲基纳迪克酸酐（MeNA）固化体系进行了放热特性分析,升 温速率分别为5k/min、10k/min、15k/min、20k/min、25k/min及35k/min。在此基础上重点提出最概然Malek Flynn Wall Ozawa分析法,对其固化反应机理进行固化动力学参数分析,建立了能够正确描述固化反应过程的机 理模型。该方法求得固化体系反应表观活化能为E=67.05kJ/mol,表观指前因子为A=5.05×109s 1,反应机理函数 为f(a)=22.24(1-a)1.76。最后通过实验数据对最概然Malek Flynn Wall Ozawa分析法进行验证,证明该方法 能够精确的描述固化反应过程和机理特征。     

TDE-85/DICY/取代脲中温固化体系的固化动力学

采用DSC研究了以双氰胺/取代脲为潜伏型中温固化体系的三官能团环氧树脂TDE-85的固化反应动力学,探讨了反应机理并确定了最佳的固化工艺参数。结果表明,固化温度<140℃时,受扩散效应和双氰胺在环氧树脂中溶解速率的影响,体系的等温固化行为与自催化模型存在偏差;固化温度>150℃后,体系的等温固化行为可用自催化反应模型很好地描述,其表观活化能为86.33 kJ/mol,指前因子为2.68×1010,总反应级数(m+n)为2～3。综合变温DSC和等温DSC的实验结果,可确定体系的最佳固化工艺条件为:120℃下预固化1 h后再升温至150℃保温1 h。     

Structural Carbon/Epoxy Prepregs Properties Comparison by Thermal and Rheological Analyses

Two different carbon/epoxy prepreg materials were characterized and compared using thermal (DSC, TGA, and DMA) and rheological analyses. A prepreg system (carbon fiber preimpregnated with epoxy resin F584) that is currently used in the commercial airplane industry was compared with a prepreg system that is a prospective candidate for the same applications (carbon fiber prepreg/epoxy resin 8552). The differences in the curing kinetics mechanisms of both prepreg systems were identified through the DSC, TGA, DMA, and rheological analyses. Based on these thermal analysis techniques, it was verified that the curing of both epoxy resin systems follow a cure kinetic of n order. Even though their reaction heats were found to be slightly different, the kinetics of these systems were nevertheless very similar. The activation energies for both prepreg systems were determined by DSC analysis, using Arrhenius's method, and were found to be quite similar. DMA measurements of the cured prepregs demonstrated that they exhibited similar degrees of cure and different glass transition temperatures. Furthermore, the use of the rheological analysis revealed small differences in the gel temperatures of the two prepreg systems that were examined.