Curing Kinetics of Liquid Crystalline Epoxy Resins Based on Bisphenol-S Mesogen with DDE by Nonisothermal DSC Data

The curing kinetics for a system of Sulfonyl bis(4,1-phenylene)bis[4-(2,3-epoxypro pyloxy)benzoate] (p-SBPEPB) with 4,4′-diaminodiphenyl ether (DDE) were investigated by nonisothermal differential scanning calorimetry (DSC). The dependencies of the apparent activation energy Ea and the conversion α during overall curing reaction were revealed by Ozawa's method. The results shown the Ea decreased drastially from 107 to 75 KJ/mol with α in the initial stages (α = 0–20%), the average apparent activation energy Ea of p-SBPEPB/DDE is 82.81 KJ/mol and was relatively constant in the 0.5 to 0.9 conversion interval. Some parameters were evaluated using the two kinetic models of ?esták–Berggren (S-B) equation and JMA model. The liquid crystalline (LC) phase had formed and was fixed in the system during the curing process.     

Processing parameters of the diethylenetriamine and unsaturated aldehyde resin

The dependence of processing parameters of the reaction between diethylenetriamine (DETA) and crotonaldehyde (CR) or cinnamaldehyde (CA) on reaction time were followed by calorimetric and viscosity measurements. Resins with molecular weights up to 800 g/mol and content of unreacted monomers under 1% were formed. The most reactive were the amino and aldehyde groups. The aldehyde groups are five times more reactive than double bonds. ? NHCHOH, ? CH₂NH? , ? CHNH? , and ? N?CH? groups were formed. The rates of the reactions and the rate constants decrease with increasing molar ratio between DETA and unsaturated aldehydes. The heat of the addition of DETA to CR was up to 54 KJ/mol and the total heat of reaction was up to 71 KJ/mol. The heat of addition of DETA to CA was up to 32 KJ/mol and the total heat of reaction was up to 61 KJ/mol. For DETA and CR the activation energy of condensation were 57.3 KJ/mol, and 42.0 KJ/mol for DETA and CA. The viscosity of the final products increased up to hard resins.     

烯丙基酚氧树脂改性BMI固化特征及动力学研究

采用DSC、IR分析研究了烯丙基酚氧树脂改性BMI树脂的固化反应过程 ,其结果表明 ,固化反应过程中的吸热和放热的共同作用使得固化反应仅有一个平缓的放热峰 ,固化反应接近于 1级反应 ,反应活化能为 10 0 .6Kj/mol。     

Kinetic study of polymerization/curing of filament-wound composite epoxy resin sytems with aromatic diamines

The kinetics of the polymerization/curing of an 80/20 blend of a diglycidyl ether of bisphenol A (DGEBA) and a diglycidyl ether of 1,4-butanediol (DGEBD) with a commercial mixture of methylene dianiline and m-phenylene diamine (Tonox 60/40) was studied, at amine/epoxy ratios ranging from 1.1 to 4.4. Fourier transform infrared (FT-IR) measurements were used to follow the extent of epoxy conversion at 18–122°C, and bulk viscosity measurements were used to define the working range of the resin. For an amine/epoxy ratio of 1.1, the activation energy for the polymerization/curing reaction (based on time to 50% epoxy conversion in the S-shaped conversion-time plots) was 11.9 kcal/mole by FT-IR. This value compared favorably with the corresponding value of 12.7 kcal/mole obtained by Moroni and co-workers in a complementary differential scanning calorimetry (DSC) study of the same system. The FT-IR conversion-time plots were fitted to a kinetic expression that can be accommodated by an autocatalytic mechanism; the expression contains two rate constants with activation energies of 13.7 and 10.0 kcal/mole, respectively. The viscosity of the curing epoxy resin was found to obey the Williams-Landel-Ferry equation, with a Di Benedetto expression for the glass transition temperature.     

Kinetics of reaction of ethylenediamine and dimeric fatty acids

Kinetic studies were carried out on the reaction between ethylenediamine and dimeric fatty acids in melt phase. The reaction was performed at 124, 130, 145, 160, 174, and 190°C and followed by determining the acid value of the product. The polyamidation reaction was found to be of overall second order with an activation energy of 18.2 kcal/g mol up to 90% conversion and of overall third order with an activation energy of 16.4 kcal/g mol above 90% conversion.     

Cure Kinetics and Thermal Property of Bisphenol-S Epoxy Resin and Phthalic Anhydride

Abstract

The cure kinetics of bisphenol-S epoxy resin (BPSER) and curing agent phthalic anhydride, with N,N-dimethyl phenzylamine as an accelerator, were studied by means of differential scanning calorimetry (DSC). Analysis of DSC data indicated that an autocatalytic behavior showed in the first stages of the cure. The autocatalytic behavior was well described by the model proposed by Kamal including two rate constants, k1 and k2, and two reaction orders, m and n. The overall reaction order, m + n, is in the range 2～3. The activation energies for k1 and k2 were 111.69 and 80.47 KJ/mol, respectively. Diffusion control was incorporated to describe the cure in the latter stages. The glass transition temperatures (T_gS) of the BPSER/anhydride samples isothermally cured partially were determined by means of torsional braid analysis (TBA). and the results showed that the reaction rate increased with increasing T_g in terms of the rate constant, but decreased with increasing conversion. The T_g of completely cured BPSER/anhydride system is about 40 K higher than that of BPAER. The thermal degradation kinetics of this system was investigated by thermogravimetric analysis (TGA). It illustrated that the thermal degradation of the BPSER/phthalic anhydride has n-order reaction kinetics.     

Thermal cure of phenylethynyl‐terminated AFR‐PEPA‐4 imide oligomer and a model compound

The thermal cure reactions of phenylethynyl terminated AFR‐PEPA‐4 oligomer and a model compound N‐phenyl‐[4‐(phenylethynyl) phthalimide] were investigated. The kinetics analysis of the thermal cure of AFR‐PEPA‐4 was determined using DSC, with modified DiBenedetto equation. The activation energy of thermal cure reaction of AFR‐PEPA‐4 oligomer is 34.1 kcal/mol with the kinetic order of one, when the reaction conversion is less than 80%. The activation energy of thermal reaction of N‐phenyl‐[4‐(phenylethynyl) phthalimide] is 41.5 kcal/mol with the kinetic order of 0.95. The cure reaction of AFR‐PEPA‐4 imide oligomer can be described as a fast first‐order reaction stage for the formation of polyenes followed by a slow diffusion‐controlled crosslinking reaction stage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4446–4453, 2006     

含二氮杂萘酮环氧树脂体系的固化反应动力学研究

以 4- (4-羟基苯基 ) - 2 ,3 -二氮杂萘 - 1-酮 (DHPZ)为固化剂 ,用示差扫描量热法 (DSC)对环氧E44 /DHPZ体系的固化反应过程作了系统的研究 ,计算出固化反应的表观活化能为 10 4 0 4kJ/mol,固化反应近似为一级反应。通过固化剂份数对化学反应程度影响的研究 ,得知当DHPZ份数为 4 5～ 5 5时固化反应完全     

Kinetics of curing reaction of urethane function on base-catalyzed epoxy reaction

The kinetic study on the effect of aromatic-connected carbamate (Ar-carbamate) on the curing reaction of phenyl glycidyl ether (PGE) catalyzed by tertiary amine was carried out through thermal analysis of the reaction by differential scanning calorimetry (DSC). By isothermal DSC analysis, the consumption rate of the epoxide group of PGE was found to be a first-order reaction in the presence of aromatic-connected carbamate in the reaction. It was found that the reaction system has a low activation energy (E_a = 4.63 kcal/mol) as compared to the system without Ar-carbamate (E_a = 6.89 kcal/mol). A reaction mechanism was proposed for this reaction system. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:121–127, 1998     

环氧树脂固化反应动力学研究及其活性增韧

采用动态DSC法跟踪环氧树脂E-51／固化剂5784体系的反应历程,确定固化温度,利用Kissinger方程和Crane方程对固化反应动力学进行分析,通过红外分析确定聚硫橡胶的增韧方式,研究不同聚硫橡胶用量列固化产物力学性能的影响,采用扫描电镜分析试样断口形貌。研究结果表明：该固化体系的动力学参数为表观活化能△E=63．946kJ／mol,指前因子Ak=1．90×10^5,反应能级n=0．91,聚硫橡胶增韧环氧树脂通过化学键合来实现,并且效果明显。     

Differential thermal analysis using high frequency dielectric heating II. Curing kinetics studies

A previous paper described the theory and equipment of Differential Thermal Analysis using High Frequency Dielectric Heating, DTA/HF. Curing studies using DTA/HF on cis-1,4-polyisoprene rubber filled with 50 phr of CaCO₃ and containing from 1.5 to 4.5 phr of dicumyl peroxide (DCP) curative indicated that below about 185°C, the curing reaction was first order with respect to DCP; the mean activation energy was 32.6 kcal/mole; and the heat of reaction ranged from 60 to 80 kcal/mole DCP. These results are in agreement with published results. Above 185°C both thermodynamic and kinetic evidence implied that the reaction mechanism changed; the first order peroxide decomposition no longer controlled the overall rate of reaction. The curing of both stereo styrene-butadiene rubber (SBR) and cis-1,4-polybutadiene rubber (BR) containing 50 phr of CaCO₃ and 0.5 phr of DCP was found to follow first order kinetics as expected. The magnitude of the heat of curing was used to determine the frequency of a vinyl propagation-type cross-linking reaction. Eight to 36 crosslinks per molecule of DCP were obtained. This reaction became more extensive at high temperature, in agreement with published results.     

用DSC法研究环氧树脂/环氧封端酚酞聚芳醚腈的固化特性

利用差示扫描量热法研究了AG - 80环氧树脂和环氧封端酚酞聚芳醚腈 (简称E -PCE)共混物中固化剂含量对树脂基体固化反应温度、反应热的影响。此共混环氧树脂基体的最低固化反应温度为1 61 .3℃ ,固化反应表观活化能为 60 .66kJ/mol,固化反应级数为 0 .875。     

环氧树脂/液晶固化剂固化反应动力学研究

通过差热分析 (DSC)研究了非等温过程环氧树脂 /液晶固化剂体系的固化反应动力学 ,研究了不同配比对固化反应的影响 ,固化反应转化率与固化温度的关系 ,计算了固化反应的活化能 ,确定了环氧树脂 /液晶固化剂的固化工艺条件 ,用偏光显微镜观察了环氧树脂 /液晶固化剂 / 4 ,4′ -二氨基二苯砜 (DDS)体系在不同温度下固化时的形态。结果表明 :液晶固化剂的加入量越大 ,固化反应速度越快 ;环氧树脂 /液晶固化剂体系固化反应的活化能为 71 5kJ/mol;偏光显微镜观察表明 :随着固化起始温度的增加 ,固化体系的形态由原来的具有各向异性的丝状结构变化为各向同性 ,液晶丝状条纹消失。     

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...     

Esterification of decanoic acid with methanol using Amberlyst 15: Reaction kinetics

Methyl decanoate is used as a surrogate fuel. The surrogate fuels are structurally similar to actual biodiesel. We synthesized methyl decanoate in a small batch reactor by esterification reaction using decanoic acid and methanol on solid acid catalyst Amberlyst 15 used in dry state. The outcome of different reaction parameters including catalyst loading, temperature, molar ratio, stirrer speed, water concentration effect, and adsorption on catalyst pellets were studied for optimization of rate of conversion. The effect of external and internal diffusion limitations on catalyst granules was calculated theoretically from the reaction kinetics data. An analysis of the reaction kinetics revealed that the esterification reaction was rate controlled by adsorption of methanol on the solid acid catalyst and the reaction can be modeled as Eley–Rideal model. Activation energy of the esterification reaction was 39.4?KJ/mol. Reaction enthalpy and entropy were found to be 29.81?kJ/mol and 87.38?J/mol. K, respectively.     

环氧树脂改性双马来酰亚胺/氰酸酯树脂固化工艺研究

采用差示扫描量热(DSC)法和红外光谱(FT-IR)法对缩水甘油胺型环氧树脂(AG-80)与脂环族缩水甘油酯型环氧树脂(TDE-85)共同改性双马来酰亚胺(BMI)/氰酸酯树脂(CE)的固化反应历程进行了研究,并按照Kissinger和Crane法计算出该改性树脂体系固化反应的动力学参数。结果表明:改性树脂体系的固化反应表观活化能为68.11 kJ/mol,固化反应级数为0.860(接近于1级反应);环氧树脂(EP)可促进CE固化,当固化工艺条件为"150℃/3 h→180℃/2 h"时,改性树脂体系可以固化完全。     

聚酰胺固化环氧树脂的热分解动力学研究

利用热重分析(TG)采用不同升温速率(10,15,20,25℃/min)分别在空气和氮气气氛下对聚酰胺固化环氧树脂热稳定性进行了研究.采用Coats-Redfem和Ozawa热分析处理动力学数据的方法,计算了环氧树脂热分解反应活化能E、反应级数n及频率因子A.求得空气气氛下5%～30%的失重率下反应表观活化能在70.3...     

单环氧基活性稀释剂对环氧酸酐体系的作用

考察添加不同量的单环氧基活性稀释剂(H8)对环氧树脂体系固化反应以及介电性能的影响,通过DSC热分析发现,稀释剂添加量越多,DSC曲线放热峰越往高温方向移动,并且峰形变钝,放热过程的△HC基本上随稀释剂用量的增大而减小;由介电损耗-温度谱实验数据显示,随着稀释剂加入量增多,介电损耗值也呈上升趋势,但总体上tanδ还是保持在较低值范围内,155℃tanδ最大值不超过0.04。同时利用DSC跟踪体系固化反应过程,根据Kissinger和Crane方程对该固化反应进行了非等温动力学分析,探讨得出环氧树脂体系的固化动力学参数:固化反应表观活化能△Ea=48.3 kJ/mol,反应级数n=0.89。     

Nickel-catalyzed hydrogenation of soybean oil: I. Kinetic,equilibrium and mass transfer determinations

The kinetic and equilibrium constants were determined for the hydrogenation of soybean oil on a commercial nickel catalyst in a 300-ml Parr batch reactor. These constants were used to calculate the hydrogen gas absorption coefficients by coupling mass transfer with reaction rate based on a Langmuir Hinshelwood model. The activation energy for the rate-determining step was 23 kcal/g mol whereas the adsorption energy for hydrogen was −12.5 kcal/g mol. The gas absorption coefficients varied between 0.3 to 0.7 min⁻¹ as the temperature ranged between 140–180 C.     

DSC法研究聚异氰酸酯／环氧树脂胶粘剂的固化反应动力学及固化工艺

采用差示扫描量热法(DSC)研究了聚异氰酸酯／环氧树脂的固化过程,研究了不同配比对固化反应的影晌,固化度与固化温度的关系,计算了固化反应表观活化能和反应级数,确定了聚异瓤酸酯／环氧树脂胶粘剂的固化工艺。结果表明:胶粘剂中固化剂的含量对环氧树脂的固化反应过程有显著的影响,随着聚异氰酸酯的增加,固化放热量增加。当聚异氰酸酯的含量达到1．2份时,固化反应放热量达到最大值;不同升温速率下,体系固化温度有很大差异,随着升温速率的提高,固化温度增加。通过动力学计算得到体系最佳固化温度为108℃,固化时间为6-8h,固化体系的活化能为43．31kJ／mol,反应级数为1．17。