助剂对不饱和聚酯树脂固化反应的影响

采用非等温示差扫描量热法(DSC)研究了添加抗氧化剂和抗紫外剂对不饱和聚酯树脂(UPR)体系固化反应的影响.通过Kissinger-Crane方程和Ozawa方程求解了反应的表观活化能、指前因子、反应级数等动力学参数.运用T-β外推法确定了UPR的凝胶温度(Tgel)、固化温度(Tcure)和后处理温度(Ttreat)...     

聚醚酮改性BMI树脂的固化反应动力学研究

采用非等温DSC(差示扫描量热)法、FT-IR(红外光谱)法、Kissinger-Crane法、Ozawa法和T-β(温度-升温速率)外推法研究了PEK(聚醚酮)改性BMI/DBA(双马来酰亚胺/二烯丙基双酚A)树脂体系的固化动力学过程。研究结果表明:采用Kissinger-Crane法得到的动力学参数与Ozawa法的求解结果相近,PEK改性BMI/DBA的固化反应遵循1级反应机制;BMI/DBA/PEK树脂体系的固化温度为130~210℃,后处理温度为240℃。     

不饱和聚酯树脂固化动力学研究进展

介绍了不饱和聚酯树脂(UPR)固化反应动力学的n级反应模型和自催化模型,指前因子(A)和表观活化能(E)的求解方法:Kissinger法,Ozawa法和Friedman法以及由Crane方程或形状指数Si求解反应级数(n)的方法,综述了目前国内外DSC法研究UPR固化动力学的进展。     

不饱和聚酯树脂/可膨胀微球体系的非等温固化动力学

采用非等温DSC法对不饱和聚酯树脂/可膨胀微球复合体系的固化行为、放热峰进行了分析;并且通过Kissinger方程和Crane方程对DSC数据进行处理求得复合体系的表观活化能、碰撞因子及反应级数等固化反应过程动力学参数;利用拉曼光谱仪与热台联用技术对不饱和聚酯树脂在可膨胀微球存在下的固化行为进行了研究。结果表明:可膨胀微球的加入促进了不饱和聚酯树脂的交联固化反应,提高了交联固化速度。此外,利用外延法对复合体系的起始固化温度、恒温固化温度以及后处理温度进行初步探讨,为固化工艺的确定提供了依据。     

DSC研究不饱和聚酯/复合引发体系固化反应动力学

本文介绍了不饱和聚酯树脂（UP）常用的几种固化反应动力学模型,实验采用差示扫描量热法（DSC）研究不饱和聚酯/复合引发体系的等温固化反应动力学。选择修正的自催化模型对等温固化DSC数据进行处理,用最小二乘法进行非线性回归,确定等温反应速率常数k0和反应级数m、n,得到动力学方程。研究结果表明不同温度下该模型拟合曲线的相关系数均在98%以上,与实验数据点相吻合,因此所选模型对该体系是适用的,为不饱和聚酯基复合材料的固化研究提供了理论依据。     

E51/DDS/CTBN/POSS-NH2环氧树脂体系固化行为研究

采用非等温差示扫描量热法对环氧树脂的固化行为进行研究.配制E51/DDS/CTBN和E51/DDS/CTBN/POSS-NH2环氧树脂体系,通过对其不同升温速率的DSC曲线进行分析得到固化特征温度.通过Kissinger和Ozawa方程计算体系的活化能,得到相关动力学参数.将动力学参数代入n级动力学反应模型,建立反应动...     

非等温DSC研究PBT/TDI固化反应动力学

采用非等温差示扫描量热法(DSC)对PBT [3, 3–双(叠氮甲基)氧杂环丁烷–四氢呋喃共聚醚]/TDI(甲苯二异氰酸酯)反应体系在不同催化剂用量、不同升温速率条件下的固化反应进行了研究,并通过Kissinger-Crane方程求解得到了表观活化能和反应级数等动力学参数。结果表明,催化剂含量不会影响PBT/TDI固化反应级数,但能显著改变固化反应活化能。     

PVA对碳酸钙、淤泥/不饱和聚酯树脂体系增强的探讨

采用聚乙烯醇(PVA)对碳酸钙、淤泥进行改性并将其作为不饱和聚酯树脂填料。研究了PVA掺量对碳酸钙/不饱和聚酯树脂和淤泥/不饱和聚酯树脂体系力学性能的影响。采用IR、DSC和SEM探讨了PVA对这2类体系的改性机理。实验结果表明:加入5%PVA后,碳酸钙/树脂体系,淤泥/树脂体系弯曲强度分别提高了55.3%和58.4%。PVA对2种体系的改性增强效应均源于PVA与填料和树脂之间氢键的桥梁作用,氢键改善了无机填料与树脂的相容性,这与以往改性剂与碳酸钙反应生成酯酸钙固化物的机理是不同的。     

酚醛型环氧树脂/双酚A型氰酸酯树脂体系固化动力学的研究

应用差示扫描量热分析(DSC)对不同比例的酚醛型环氧树脂/双酚A型氰酸酯树脂体系固化动力学进行了研究,并通过Kissinger法、Ozawa法和Crane法求得了体系的固化动力学参数。结果表明,当环氧树脂与氰酸酯的摩尔比为2∶1时,由Kissinger法和Ozawa法计算得到的表观活化能在体系中最小,分别为49.05 kJ/mol和54.86 kJ/mol,Crane方程求得的表观反应级数为1~2。     

TBPB/TBPO引发不饱和聚酯树脂固化动力学研究

采用非等温DSC法研究了过氧化苯甲酸叔丁酯(TBPB)/过氧化辛酸酯(TBPO)引发不饱和聚酯体系的固化行为以及TBPO含量对固化反应温度的影响。通过Kissinger和Ozawa方程计算得到固化反应的表观活化能。研究表明,随着TBPO含量增加,固化反应温度降低。TBPO的质量分数从0增加到40%时,Kissinger方程得到的活化能从4.4 kJ/mol降为2.3 kJ/mol,Ozawa方程的结果与之趋势一致。     

纳米TiO2/UPR复合体系的固化动力学及固化工艺研究

采用动态差示扫描量热法（DSC）对纳米TiO2／UPR复合体系的固化过程进行研究,得出不同升温速率下纳米TiO2／UPR复合体系固化过程中的DSC曲线;并根据动态DSC曲线求出固化反应的表观活化能、固化反应级数及动力学方程中的指前因子等参数;建立了复合体系固化反应动力学的数学模型并且确定了分阶段变温固化新工艺。     

Photopolymerization kinetics of 2-phenylethyl (meth)acrylates studied by photo DSC

The present work deals with the photopolymerization of 2-phenylethyl (meth)acrylates and estimation of their kinetic parameters. Formulations were made by independently homogenizing the monomers with photoinitiators of two different classes. Two different compositions of photoinitiators were used to study the effect of concentration of photoinitiator on cure kinetics. These compositions obtained were tested for photo curing performance using differential photocalorimetry (DPC) or photo DSC under polychromatic radiation. The heat flow against time was recorded for all formulations under isothermal conditions and the rates of polymerization as well as the percentage conversions were estimated. It was observed that due to a longer timescale for reaction diffusion, the methacrylate formulations showed a higher conversion than acrylate formulations. Other parameters such as induction time, maximum rate and conversion attained as well as the time to attain peak maximum were noted. The photopolymerization and kinetic estimations of the formulations including evaluation of kinetic models are discussed.     

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.     

Photopolymerization kinetics of bis-aromatic based urethane acrylate macromonomers in the presence of reactive diluent

The present work deals with the photopolymerization of bis-aromatic based urethane acrylate macromonomers in the presence of excess end capping agent as reactive diluent and estimation of their kinetic parameters. Formulations were made by independently homogenizing the macromonomers with photoinitiators of three different classes. Three different compositions of photoinitiators were used to study the effect of concentration of photoinitiator on cure kinetics. These compositions obtained were tested for photo curing performance using photo DSC under polychromatic radiation. The heat flows against time were recorded for all formulations under isothermal condition and the rates of polymerization, peak maximum times as well as the percentage conversions were estimated. It was observed that due to a longer timescale for reaction diffusion, formulations with macromonomer containing propoxylated backbone showed higher conversions than the corresponding ethoxylated analogue. The photopolymerization and kinetic estimations of the formulations including evaluation of kinetic model are discussed.     

MAP-POSS改性不饱和聚酯树脂的固化反应

为改进不饱和聚酯（UP）树脂的性能,用非等温差示扫描量热法（DSC）研究了甲基丙烯酰氧丙基笼形倍半硅氧烷（MAP-POSS）与通用UP树脂的共同化反应。UP、苯乙烯和MAP—POSS有较好的相容性,可共同固化,MAP-POSS可均匀分散在UP基体中形成原位纳米分子复合材料。测定了固化动力学参数,建立了固化反应动力学数学模型。     

The effect of bismaleimide resin on curing kinetics of epoxy–amine thermosets

An analysis of the cure kinetics of several formulations composed of diglycidyl ether of bisphenol-A (DGEBPA) and aromatic diamines, methylenedianiline (MDA) and diaminodiphenyl sulfone (DDS), in the absence and presence of 4,4′-bismaleimidodiphenylmethane (BM) was performed. The dynamic differential scanning calorimetry (DSC) thermograms were analyzed with the help of ASTM kinetic software to determine the kinetic parameters of the curing reactions, including the activation energy, preexponential factor, rate constant, and 60 min ½ life temperature. The effects of substitution of one curing agent for another, their concentration, and the absence and presence of BM resin and its concentration on curing behavior, ethalpy, and kinetic parameters are discussed. © 1996 John Wiley & Sons, Inc.     

Monitoring the cure of an epoxy-anhydride resin

The cure of an epoxy-anhydride resin system used in pultrusion was characterized to develop an understanding of the cure behavior and to determine potential process controls parameters. Isothermal cures of neat resin formulations were monitored by differential scanning calorimetry (DSC), torsional braid analysis (TBA), and microdielectrometry (MDE). The processing conditions define a time/ temperature region in which monitoring would be applicable. Both DSC and MDE were found to yield useful information in this region, however, the events typically monitored by TBA either did not occur or occurred too quickly to be monitored. Significant ionic conductivity was observed in the fully cured resins at temperatures above the glass transition temperature and could possibly be used as a control parameter. This study revealed an apparent change in reaction mechanism with increasing cure temperature. DSC showed a change in activation energy with extent of reaction and a decrease in heat of reaction at the higher isothermal cure temperatures. The formation of a different network structure was indicated by a decreasing glass transition temperature of the cured resin with increasing cure temperature by both DSC and TBA.     

A kinetic model for sulfur accelerated vulcanization of a natural rubber compound

Vulcanization kinetics for a natural rubber compound were studied by a kinetic approach using the cure meter and DSC methods. A simplified but realistic model reaction scheme was used to simulate induction, curing, and overcure periods continuously. Physically significant parameters of the model were extracted from isothermal experimental data using a cure meter. The calculation demonstrated a good correspondence with isothermal cure meter data over the temperature range studied. The length of induction time, variation of maximum modulus with temperature, and the reversion phenomena observed from cure curves can be predicted. DSC data were found to be incompatible with the cure meter test, because the complex vulcanization reaction system is multiexothermal and it is difficult to isolate the heat due to crosslinking. Hence, the cure meter technique is suggested for the study of crosslink formation. The kinetic approach provides a way to incorporate vulcanization kinetics into simulation of reactive processing operations. © 1996 John Wiley & Sons, Inc.     

Isothermal differential scanning calorimetry study of the cure kinetics of a novel aromatic maleimide with an acetylene terminal

An isothermal differential scanning calorimetry (DSC) study on the cure kinetics was performed on N-(3-acetylenephenyl)maleimide (3-APMI) monomer to determine a suitable cure model. The 3-APMI monomer reported in our prior article was a novel aromatic maleimide monomer with an acetylene terminal that would be an ideal candidate for heat-resistant composites. The isothermal DSC study was carried out in the temperature range 150–200°C. Although the cure temperatures were different, the shapes of the conversion curves were similar, and all of the cure reactions could be described by an nth-order kinetic model. In particular, the cure reaction at the initial stage was a first-order kinetic reaction. The cure kinetic parameters of the 3-APMI monomer, including the reaction model, activation energy, and frequency factor, were determined. This information was very useful for defining the process parameters, final properties, and quality control of the cured 3-APMI monomer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Kinetic study of the effect of catalysts on the curing of biphenyl epoxy resin

The investigation of cure kinetics of biphenyl epoxy (4,4′-diglycidyloxy-3,3′,5,5′-tetramethyl biphenyl)dicyclopentadiene type phenolic resin system with different kinds of catalysts was performed by a differential scanning calorimeter 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 indicate that the curing reaction of the formulations using triphenylphosphine (TPP), 1-benzyl-2-methylimidazole (1B2MI), and tris(4-methoxyphenyl)phosphine (TPAP) as a catalyst proceeds through an nth-order kinetic mechanism, whereas thatof the formulations using diazabicycloundecene (DBU) and tetraphenyl phosphonium tetraphenyl borate (TPP–TPB) proceeds by an autocatalytic kinetic mechanism. To describe the cure reaction in the latter stage, we have used semiempirical relationship proposed by Chern and Poehlein. By combining an nth-order kinetic model or an auto-catalytic model with a diffusion factor, it is possible to predict the cure kinetics of each catalytic system over the whole range of conversion. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1125–1137, 1998