Polymerization kinetics and thermal properties of dicyanate/clay nanocomposites

The polymerization kinetics and thermal properties of dicyanate/clay nanocomposites were investigated. A type of organically modified clay was used as nanometer‐size fillers for the thermosetting dicyanate resin. Differential scanning calorimetry (DSC) was used to study the curing behavior of the dicyanate/clay nanocomposite systems. The polymerization rate of the nanocomposite systems increased with increasing clay content. An autocatalytic reaction mechanism could adequately describe the polymerization kinetics of the dicyanate/clay nanocomposite systems. The polymerization kinetic parameters were determined by fitting the DSC conversion data to the proposed kinetic equation. The glass‐transition temperature of the dicyanate/clay nanocomposites increased with increasing clay content. The thermal decomposition behavior of the dicyanate/clay nanocomposites was investigated by thermogravimetric analysis. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1955–1960, 2004     

Reaction kinetics and characteristics of polyurethane/clay nanocomposites

The reaction behavior and physical properties of polyurethane (PU)/clay nanocomposite systems were investigated. Organically modified clay was used as nanofillers to formulate the nanocomposites. Differential scanning calorimetry was used to study the reaction behavior of the PU/clay nanocomposite systems. The reaction rate of the nanocomposite systems increased with increasing clay content. The reaction kinetic parameters of proposed kinetic equations were determined by numerical methods. The glass transition temperatures of the PU/clay nanocomposite systems increased with increasing clay content. The thermal decomposition behavior of the PU/clay nanocomposites was measured by using thermogravimetric analysis. X‐ray diffractometer and transmission electronic microscope data showed the intercalation of PU resin between the silicate layers of the clay in the PU/clay nanocomposites. A universal testing machine was used to investigate the tensile properties of the PU/clay nanocomposites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1641–1647, 2005     

基于变活化能模型的T800/环氧树脂预浸料固化反应动力学研究

为了深入了解某新型高温固化T800/环氧树脂预浸料的固化行为,借助差示扫描量热仪(DSC),采用非等温DSC法研究了T800/环氧树脂预浸料的固化反应过程。基于唯象模型,系统研究了该预浸料的固化反应特征温度及固化动力学参数,确定该预浸料中环氧树脂的固化反应动力学模型为自催化模型。采用等转化率法,分析了预浸料中环氧树脂的反应活化能随固化度的变化情况,结果表明在整个固化反应过程中,树脂固化反应活化能变化较大,传统模型法基于全固化过程活化能不变的假设无法准确描述该固化反应。采用变活化能自催化模型,利用粒子群全局优化算法,得到了T800/环氧树脂预浸料的固化动力学方程,结果表明该模型能较好地描述实验现象,可为进一步研究该预浸料的热力学性能及其成型过程中的质量控制提供理论基础。     

Cure kinetics and properties of epoxy/dicyanate blends

The cure behavior and properties of epoxy/dicyanate blends containing a stoichiometric amount of an amine curing agent for epoxilde groups were investigated as a function of blend composition. Differential scanning calorimetry (DSC) was used to investigate the dynamic and isothermal cure behavior of the blends. The cure rate of the blend increased with increasing dicyanate content. A second order autocatalytic reaction mechanism described the cure kinetics of the blends. The kinetic parameters were determined by fitting the dynamic DSC data to the model kinetic equation. The k₁₀ and E₁ values were mainly affected by the change of dicyanate content. The glass transition temperature of the blend decreased with increasing dicyanate content. The thermal decomposition characteristics of the blends were investigated by thermogravimetric analysis (TGA). Dynamic mechanical analysis (DMA) and thermal mechanical analysis (TMA) were used to investigate the mechanical properties of the blends. With increasing dicyanate content, the cure rate increased but the thermal and mechanical properties of the cured blends were not improved.     

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.     

Synthesis,characterization, and curing of {2,6–bis‐[2‐(bis‐oxiranylmethyl‐amino)‐methylbenzyl]‐phenyl}‐bis‐oxiranylmethylamine (BPBOMA)

The curing behavior of epoxy resin prepared by reacting epichlorohydrin with amine functional aniline acetaldehyde condensate (AFAAC) was investigated using AFAAC as a curing agent. The epoxy resin, {2,6‐bis‐[2‐(bis‐oxiranylmethyl‐amino)‐methylbenzyl]‐phenyl}‐bis‐oxiranylmethylamine (BPBOMA), was characterized by FTIR and ¹H‐NMR spectroscopy, viscosity measurement, and determination of epoxy content. Analysis of the curing reaction was followed by differential scanning calorimetry (DSC) analysis. To investigate the curing kinetic with AFAAC, dynamic DSC scans were made at heating rates of 5, 10, 15, and 20°C/min. The activation energy and frequency factor of the AFAAC formulation were evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3168–3174, 2006     

Layered silicate nanocomposites based on various high‐functionality epoxy resins: The influence of an organoclay on resin cure

The influence of an organically modified clay on the curing behavior of three epoxy systems widely used in the aerospace industry and of different structures and functionalities was studied. Diglycidyl ether of bisphenol A (DGEBA), triglycidyl p‐amino phenol (TGAP) and tetraglycidyl diamino diphenylmethane (TGDDM) were mixed with an octadecyl ammonium ion modified organoclay and cured with diethyltoluene diamine (DETDA). The techniques of dynamic mechanical thermal analysis (DMTA), chemorheology and differential scanning calorimetry (DSC) were applied to investigate gelation and vitrification behavior, as well as catalytic effects of the clay on resin cure. While the formation of layered silicate nanocomposite based on the bifunctional DGEBA resin has been previously investigated to some extent, this paper represents the first detailed study of the cure behavior of different high performance, epoxy nanocomposite systems.     

Cure kinetics and physical properties of dicyanate/polyetherimide semi‐IPNs

The curing behavior and physical properties of dicyanate/polyetherimide (PEI) semi‐interpenetrating polymer network (IPN) systems were investigated. Differential scanning calorimetry (DSC) was used to study the curing behavior of the dicyanate/PEI semi‐IPN systems. The curing rate of the semi‐IPN system decreased as the PEI content increased. An autocatalytic reaction mechanism can describe well the curing kinetics of the semi‐IPN systems. The reaction kinetic parameters were determined by fitting DSC conversion data to the kinetic equation. The glass transition temperature of the semi‐IPNs decreased with increasing PEI content. Two glass transitions due to phase‐separated morphology were observed for the semi‐IPN containing over 15 phr (parts per hundred parts of dicyanate resin) PEI. The thermal stability and dynamic mechanical properties of the semi‐IPNs were measured by thermal analysis.     

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     

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。     

环氧树脂插层纳米复合材料固化动力学研究

运用自制的有机蒙脱土，采用浇模固化成型法制备环氧树脂／二乙烯三胺／有机蒙脱土纳米复合材料，对固化产物利用XRD（X射线衍射）分析有机蒙脱土的层间距变化，确定产物为插层型的纳米复合材料，并用DSC（差示扫描量热法）跟踪环氧树脂固化行为。运用Kissinger,Flynn-Wall-Ozawa,Crane方法对环氧树脂的固化反应过程进行分析，求出活化能和反应级数等动力学以在数。结果发现，加入有机化蒙脱土后使固化反应活化能和频率下降，从而有利于固化工艺的实现，便于纳米复合材料实际应用。     

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     

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。     

环氧树脂固化动力学的非等温DSC研究

用非等温DSC对环氧树脂在动态升温过程中的固化动力学进行了研究,采用Kissinger方程对固化动力学模型参数中固化反应活化能、反应级数和指前因子进行了计算,并用Ozawa法对固化反应活化能进行了验证,计算结果表明,EP/DDS固化反应符合n阶固化动力学模型,结合不同升温速率下的特征温度,对环氧树脂的固化条件进行了优化。     

聚氨酯柔性固化剂/环氧体系固化动力学及机理

通过不同升温速率下示差扫描量热分析(DSC)研究了自制的聚氨酯柔性固化剂ATPU/环氧树脂E-44体系的固化反应动力学及机理。通过Kissinger和Crane方程求解了表观活化能和反应级数等动力学参数,并运用该参数研究了固化反应速率常数、固化反应速率、固化度等的变化规律及影响因素。通过反应级数的研究证明了固化反应为一复杂反应,不同的固化交联反应同时发生,但主要进行的是伯氨基及仲氨基与环氧基之间的反应,该类反应使得体系得以固化。     

聚苯醚/环氧树脂体系的固化反应研究

用动态差示扫描量热法研究了PPO/EP体系的固化反应,其反应热和最大放热峰的峰温均随着PPO含量的增加而减小。采用程序升温DSC法,用Kissinger方程研究了PPO/EP体系的动力学特征,并计算得到了一些重要的动力学参数如表观活化能、反应级数等。红外和DSC研究表明,PPO/EP体系在固化过程中由于体系凝胶、EP分子量逐步增加以及PPO的存在引起体系的粘度升高等原因,导致固化反应没有进行完全。     

Curing behavior and properties of epoxy nanocomposites with amine functionalized multiwall carbon nanotubes

Carbon nanotubes (CNTs) with reactive functional groups such as amines would affect not only properties but also curing behavior of an epoxy nanocomposite system comprising them. Therefore, in this study, an amine functionalization of multiwall CNTs (MWNTs) was carried out via treating pristine MWNTs (PMWNT) with 4‐aminobenzoic acid in polyphosphoric acid. The functionalization was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Epoxy nanocomposites comprising the PMWNT or functionalized MWNTs (FMWNT) were prepared and their curing behavior and properties were investigated. Differential scanning calorimetry (DSC) was used to obtain experimental conversion data for curing kinetic analysis. The FMWNT accelerated the curing rate of the nanocomposite system. The functionalization induced strong interfacial bonding between the epoxy matrix and the MWNTs, and resulted in considerable improvements in the properties of the nanocomposites. The SEM image showed strong interfacial bonding between the epoxy matrix and the FMWNT. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

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     

聚苯醚/环氧体系非等温固化行为及固化工艺

采用程序升温差示扫描量热仪（DSC）法,用Kissinger方程研究了聚苯醚（PPE）/环氧（EP）体系不同配比混合物的固化反应动力学特征。非等温DSC研究表明PPE/EP体系的固化反应过程比较复杂,其动力学参数受PPE含量的影响较大,PPE/EP混合物的固化反应起始温度随PPE含量的增大而增大,最大放热峰的峰温均随着PPE含量的增加而减小。Kissinger法计算得到PPE/EP体系10% PPE、20% PPE、40% PPE含量（质量）的表观活化能依次为63.88、55.37、47.31 kJ·mol^-1, 说明PPE可以促进环氧树脂的固化反应。在此基础上,以20% PPE/EP体系为例,采用T - β 图外推法,得到了其固化工艺     

甲酚甲醛环氧树脂体系固化过程的研究——Ⅰ.热分析技术研究固化反应及其动力学

利用差示扫描量热法(DSC)、热重分析(TG)研究了甲酚甲醛环氧树脂体系中固化剂含量和促进剂含量对固化反应和树脂体系热性能的影响,同时测定了树脂体系的固化反应动力学参数,固化反应表观活化能为80.15J/mol,反应级数为0.89。