Isothermal and nonisothermal cure kinetics of an epoxy/poly(oxypropylene)diamine/octadecylammonium modified montmorillonite system

The effect of an octadecylammonium‐exchanged montmorillonite on the curing kinetics of a thermoset system based on a bisphenol A epoxy resin and a poly(oxypropylene)diamine curing agent were studied with differential scanning calorimetry (DSC) in isothermal and dynamic (constant‐heating‐rate) conditions. Montmorillonite and the prepared composites were characterized by X‐ray diffraction analysis and simultaneous DSC and thermogravimetric analysis. The analysis of the DSC data indicated that the intercalated octadecylammonium cations catalyzed the epoxy–amine polymerization. A kinetic model, arising from an autocatalyzed reaction mechanism, was applied to the DSC data. Fairly good agreement between the experimental data and the modeling data was obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1765–1771, 2006     

Isothermal Curing Kinetics and Thermal Degradation of o-CFER/MeTHPA/O-MMT Nanocomposite

The isothermal curing kinetics of nanocomposite of o-cresol-formaldehyde epoxy resin (o-CFER), 3-methyl-tetrahydrophthalic anhydride (MeTHPA) with organic montmorillonite (O-MMT) were investigated by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC) using N,N-dimethyl-benzylamine as a curing accelerant. The XRD result indicates that an exfoliated O-MMT nanocomposite was obtained. The analysis of DSC data indicated that an autocatalytic behavior appeared in the first stages of the cure for the system, which could be well described by the Kamal model. In the later stages, the reaction is mainly controlled by diffusion and a diffusion factor, f(α), was introduced into Kamal's equation. In this way, the curing kinetics were predicted well over the entire range of conversion. The thermal degradation kinetics of this composite were investigated by thermogravimetric analysis (TGA), which revealed that with increasing O-MMT content, TG curves shift to higher temperature.     

BMI／ER／DDS三元体系固化反应动力学研究

用差示扫描量热(DSC)研究了BMI／ER／DDS三元固化体系的反应动力学,计算出了表观活化能△E、碰撞因子A和反应级数n,并结合傅里叶变换红外光谱(FTIR)对反应机理进行了探讨,指出了反应过程中生成的叔胺对固化反应的进行有重要促进作用,为进一步研究耐高温复合材料、胶粘剂等奠定了基础。     

F-51／DDS／PES三元树脂体系的固化反应动力学研究

结合测量凝胶化8寸间以及粘度与温度的关系,用差示扫描量热法(DSC)研究了F-51／DDS／PES三元树脂体系的固化反应动力学,计算出了表观活化能△E、碰撞因子A和反应级数n,并结合傅里叶变换红外光谱对反应机理进行了探讨,指出了反应过程中多元胺类固化剂分步反应对固化反应的进行有重要促进作用,为进一步研究耐高温复合材料、胶粘剂等奠定了基础。     

双马来酰亚胺/苯并噁嗪/石墨烯共聚物固化动力学及力学性能的研究

通过差示扫描量热法对双马来酰亚胺/苯并噁嗪/石墨烯（BMI /BOZ/GNS）共聚物进行了动力学研究。通过Kissinger法和Ozawa法求得了BMI /BOZ/GNS共聚物的固化动力学参数,进而研究了GNS对BMI /BOZ共聚物力学性能的影响。结果表明,随着GNS含量的增加,BMI /BOZ/GNS树脂体系的拉伸性能先增加后减小;当GNS含量为0.15 %（质量分数,下同）时,BMI /BOZ/GNS树脂体系的力学性能最优。     

Cure kinetics of epoxy resins and aromatic diamines

An analysis of the cure kinetics of several different formulations composed of bifunctional epoxy resins and aromatic diamines was performed. A series of isothermal differential scanning calorimetry (DSC) runs (at higher temperature) and Fourier transform infrared spectroscopy (FT-IR) runs (at lower temperature) provided information about the kinetics of cure in the temperature range 18–160°C. All kinetic parameters of the curing reaction, including the reaction rate order, activation energy, and frequency factor were calculated and reported. Dynamic and isothermal DSC yielded different results. An explanation was offered in terms of different curing mechanisms which prevail under different curing conditions. A mechanism scheme was proposed to account for various possible reactions during cure.     

nano-SiO_2/BCE/BMI复合材料的固化动力学的研究

采用非等温差示扫描量热法（DSC）研究了nano-SiO2填充BCE/BMI（nano-SiO2/BCE/BMI）体系的固化动力学,用Kissinger、Crane和Ozawa法确定固化动力学参数。结果表明,nano-SiO2/BCE/BMI体系的固化反应表观活化能和频率因子为293.69 kJ.mol-1和4.5×1033 s-1;反应级数为0.97;nano-SiO2/BCE/BMI体系的固化工艺参数：凝胶温度为117.28℃、固化温度为184.78℃及后处理温度为234.84℃。     

环氧树脂/超支化聚酰胺-胺固化动力学研究

采用示差扫描量热仪,通过动态DSC法研究了环氧树脂/超支化聚酰胺-胺固化体系在5,10,15,20℃/min等4个不同升温速度下的固化过程。采用Kissinger法求得表观活化能Ea为54.9 kJ/mol,通过Malek法对DSC曲线处理得到了动力学参数。根据特征函数y(α)与Z(α)的形状与特征值,得到了最佳动力学模型为两参数(m,n)的自催化模型-Sestak-Berggren方程。通过对比可知理论曲线与实验的DSC曲线有很好的一致性。     

纳米二氧化钛对环氧树脂固化反应的影响

采用非等温DSC研究了纳米二氧化钛改性环氧树脂体系(EP)的固化动力学,采用Flynn-Wall-Ozawa和Vyazovkin非线性等转化率方法(NLV)法分析了固化活化能与转化率的关系,利用Kissinger和Crane方程研究了固化动力学参数,根据不同升温速率下DSC固化反应曲线确定了固化工艺参数。结果表明,纳米二氧化钛促进了环氧树脂的固化,降低了固化反应的活化能,但没有改变环氧树脂的固化机理。     

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.     

Curing kinetics and thermal property characterization of o‐CFER/MeTHPA/O‐MMT nanocomposite

The kinetics of the cure reaction for a system of o‐cresol‐formaldehyde epoxy resin (o‐CFER), 3‐methyl‐tetrahydrophthalic anhydride (MeTHPA), N,N‐dimethyl‐benzylamine, and organic montmorillonite(O‐MMT) were investigated by means of X‐ray diffraction (XRD) and differential scanning calorimetry (DSC). The XRD result indicates that an exfoliated nanocomposite was obtained. The analysis of DSC data indicated the behavior was shown in the first stages of the cure for the system, which could be well described by the model proposed by Kamal. In the later stages, the reaction is mainly controlled by diffusion, and diffusion factor, f(α), was introduced into Kamal's equation. In this way, the curing kinetics was predicted well over the entire range of conversion. Molecular mechanism for curing reaction was discussed. The thermal degradation kinetics of the system were investigated by thermogravimetric analysis (TGA), which revealed that with the increase of O‐MMT content, TG curves shift to higher temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3023–3032, 2006     

偶联剂表面处理nano-SiO2填充BCE/BMI体系的固化动力学研究

采用非等温差示扫描量热法（DSC）研究了偶联剂KH560处理的nano-SiO2填充BCE/BMI体系（nano-SiO2/BCE/BMI）的固化动力学,用Kissinger、Crane和Ozawa法确定固化动力学参数。结果表明,nano-SiO2/BCE/BMI体系的固化反应表观活化能为65.05 kJ.mol-1和6.61×106 s-1;反应级数为0.89;nano-SiO2/BCE/BMI体系的固化工艺参数：凝胶温度为116.33℃、固化温度为163.34℃及后处理温度为213.27℃。     

Effects of diffusion on the kinetic study and TTT cure diagram for an epoxy/diamine system

The curing reactions of an epoxy system consisting of a diglycidyl ether of bisphenol A (BADGE n = 0) and 1,2-diamine cyclohexane (DCH) were studied to determine a time–temperature–transformation (TTT) isothermal cure diagram for this system. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and a solubility test were used to obtain the different experimental data reported. Two models, one based solely on chemical kinetics and the other accounting for diffusion, were used and compared to the experimental data. The inclusion of a diffusion factor in the second model allowed for the cure kinetics to be predicted over the whole range of conversion covering both pre- and post-vitrification stages. The investigation was made in the temperature range 60–100°C, which is considered optimum for the isothermal curing of the epoxy system studied. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1931–1938, 1998     

Curing kinetics and mechanical properties of fast curing epoxy resins with isophorone diamine and N-(3-aminopropyl)-imidazole

Fast curing epoxy resins were prepared by the reactions of diglycidyl ether of bisphenol A with isophorone diamine (IPD) and N-(3-aminopropyl)-imidazole (API), and their curing kinetics and mechanical properties influenced by IPD content were also investigated. The analysis of curing kinetics was based on the nonisothermal differential scanning calorimetry (DSC) data with the typical Kissinger, Ozawa, and Flynn–Wall–Ozawa models, respectively. The glass-transition temperature was also measured by the same technique. Additionally, the mechanical properties including flexural, impact, and tensile performances were tested, and the curing time was estimated by isothermal DSC. The degree of cure (α) dependency of activation energy (E_a ) revealed the complexity of curing reaction. Detailed analysis of the curing kinetics at the molecular level indicated that the dependence of E_a on the α was a combined effect of addition reaction, autocatalytic reaction, viscosity, and steric hindrance. From the nonisothermal curves, the curing reaction mechanism could be proposed according to the increasingly obvious low temperature peaks generated by the addition reaction of epoxy group with the primary amines in API and IPD molecules. Using the preferred resin formulation, the resin system could be cured within 10 min at 120 °C with a relatively good mechanical performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47950.     

Curing of unsaturated polyester resins with low exotherm peak

The curing behavior of an unsaturated polyester resin with low exotherm peak was studied by a standard procedure and by differential scanning calorimetry (DSC). A copper salt and α-methylstyrene were used as the polymerization retarders. The influence of the retarders on the exotherm peak temperature, gelation time, exothermic heat and the polymerization kinetics was investigated.     

Influence of the epoxy functionalization of multiwall carbon nanotubes on the nonisothermal cure kinetics and thermal properties of epoxy/multiwall carbon nanotube nanocomposites

Multiwall carbon nanotubes were functionalized with epoxy groups by chemical modification in four stages. At each stage, the compound was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). Epoxy composite samples were prepared by mixing diglycidyl ether of bisphenol A‐based epoxy resin and synthetic epoxy‐functionalized multiwall carbon nanotube (E‐MWCNT) with different percentages (1, 3, 6, 9, 12, and 15%) in acetone. Ultrasonic dispersion was used to produce homogenous blends. The optimum ratio of the reacting components (9%) was investigated by total enthalpy of the curing reaction from differential scanning calorimetry (DSC) thermograms. The kinetics of the curing reaction for epoxy composites with 4,4′‐diaminodiphenylsolfon as a curing agent was studied by means of a DSC nonisothermal technique. The kinetic parameters such as activation energy, pre‐exponential factor, and rate constant were obtained from DSC data. The structure ofthe nanocomposites and dispersion of the E‐MWCNTs in the nanocomposites were observed using SEM, and the thermal properties were studied by thermogravimetric analysis. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Curing behavior of epoxy resin/tung oil anhydride exfoliated nanocomposite by differential scanning calorimetry

The nanocomposite of epoxy resin/tung oil anhydride/organic montmorillonite was prepared by casting and curing. The distance of the clay gallery rose and the exfoliated nanocomposite was formed. The exfoliation behaviors of the nanocomposite had been investigated by X‐ray diffraction (XRD). The curing mechanism and kinetics of epoxy resin with the different amounts of organic montmorillonite were studied using isothermal and dynamic methods by differential scanning calorimetry (DSC). Some parameters, the activation energy and reaction orders, were calculated by the modified Avrami equation in analysis of the isothermal experiment. The total curing mechanism and kinetics of curing reaction were also analyzed by the Flynn–Wall–Ozawa method. It was noted that the instantaneous activity energy during the curing process could be obtained by the Flynn–Wall–Ozawa method and the trend of the results was in agreement with those obtained from the modified Avrami equation. These results show that the activity energy decreases with the addition of organic montmorillonite. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3822–3829, 2004     

Curing behavior and network formation of cyanate ester resin/polyethylene glycol

The mechanism and kinetics of the curing reaction of cyanate ester (CE) resin modified with polyethylene glycol were investigated by means of differential scanning calorimetry (DSC) and Fourier‐transform infrared spectroscopy (FTIR). The relationship of heat flow versus conversion rate was used to evaluate the effects of polyethylene glycol (PEG) on the curing reaction of CE. DSC results showed that the addition of PEG decreased the curing temperature of CE effectively when its content was less than 20 wt %. The curing behavior of CE/PEG still complies with the self‐catalytic kinetic model proposed by Kamal. The effects of PEG content on the kinetics parameters and conversion rate of the curing reaction were discussed. FTIR results indicated that the –OH groups in PEG participated in the polymeric reaction of CE and formed –O–C (=NH) –O– structure through block copolymerization, which extended the chain length between triazine rings and reduced the density of triazine rings. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41841.     

TPP/PMMA复合物促进环氧树脂/酸酐体系的固化动力学研究

以三苯基膦(TPP)和甲基丙烯酸甲酯(MMA)为原料合成了TPP/PMMA复合物,用DSC研究了TPP/PMMA催化双酚A二缩水甘油醚(EP828)/甲基四氢苯酐(MTHPA)体系固化反应动力学。非等温固化动力学研究结果表明,转化率在20%～60%范围内,用Ozawa法能较好地描述环氧树脂/酸酐体系的固化反应过程。