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℃。     

POSS改性BMI树脂固化动力学及固化工艺研究

以双马来酰亚胺(BMI)、二烯丙基双酚A(BA)和七苯基倍半硅氧烷三硅醇(POSS-triol)为原料,采用非等温差示扫描量热(DSC)法研究了BMI/BA/POSS-triol体系的固化反应过程。运用Kissinger极值法、Crane法、Flynn-Wall-Ozawa(FWO)等转化率法和T-β(温度-升温速率)外推法确定了改性树脂体系的固化反应动力学参数和固化工艺参数。结果表明:改性树脂体系的固化反应活化能和反应级数(接近于1)均随POSS-triol用量增加而变化不大,说明POSS-triol的加入并没有明显改变BMI/BA体系的固化反应机理;改性树脂体系的凝胶温度为175.7℃,固化温度为226.9℃,后处理温度为271.7℃。     

Curing kinetics and mechanism of novel high performance hyperbranched polysiloxane/bismaleimide/cyanate ester resins for resin transfer molding

Curing kinetics and mechanism determine the structure and property of thermosetting resins and related composites. The curing kinetics and mechanism of a novel high performance resin system based on hyperbranched polysiloxane (HBPSi), 2,2′‐diallylbisphenol A modified bismaleimide (BD), and cyanate ester (CE) resins for Resin Transfer Molding (RTM) technique were systemically studied by Differential Scanning Calorimetry (DSC), Fourier Transform Infrared (FTIR) spectra, and torque rheometer. Results show that the addition of HBPSi to BD/CE resin not only decreases the initial curing temperature and apparent activation energy, but also changes the curing mechanism, and thus the structure and properties of resultant crosslinked networks. An “Interpenetrating network (IPN)‐coupling structure” is proposed to be formed in the HBPSi/BD/CE system, which is different from traditional “IPN” structure in BD/CE resin. The simulation of curing reaction suggests that the variety of the curing activity leads to the difference between the curing behaviors of BD/CE and HBPSi/BD/CE resins, which is in good agreement with FTIR and DSC analyses. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

纳米SiO_2改性EP/BMI/CE树脂体系固化动力学研究

采用非等温差示扫描量热(DSC)法对纳米二氧化硅/环氧树脂/双马来酰亚胺/氰酸酯(nano-SiO2/EP/BMI/CE)树脂进行了固化反应动力学和固化工艺研究。通过Kissinger法和Ozawa法求得了nano-SiO2/EP/BMI/CE树脂体系固化反应动力学的表观活化能。结果表明:改性CE树脂体系的固化工艺参数为凝胶温度112℃、固化温度195℃及后处理温度213℃,进而确定了改性CE树脂体系的最佳固化工艺条件为"150℃/3 h→180℃/3 h→200℃/2 h";改性CE树脂体系的平均表观活化能为59.90 kJ/mol。     

Electron‐beam curing of bismaleimide‐reactive diluent resins

Electron‐beam (E‐beam) curing of 4,4′‐bismaleimidodiphenylmethane (BMPM)/BMI‐1,3‐tolyl/o,o′‐diallylbisphenol A (DABPA)–based bismaleimide (BMI) systems and their mixing with various reactive diluents, such as N‐vinylpyrrolidone (NVP) and styrene, were investigated to elucidate how temperature, electron‐beam dosage, and diluent concentration affect the cure extent. The effect of free‐radical initiator on the cure reactions was also studied. It was found that low‐intensity E‐beam exposures cannot cause the polymerization of BMI. High‐intensity E‐beam exposures give high reaction conversion attributed to a high temperature increase, which induced thermal curing. It was shown that the dilution and activation of NVP in BMI cause a more complete BMI cure reaction under E‐beam radiation. BMI/NVP can be initiated easily by low‐intensity E‐beam without thermal curing. FTIR studies indicate that about 70% of the reaction is complete for BMI/NVP with 200 kGy dosage exposure at 10 kGy per pass. The sample temperature only reaches about 75°C. The free‐radical initiator, dicumyl peroxide, can accelerate the reaction rate at the beginning of E‐beam exposure, but does not affect the final reaction conversion. The increase of the concentration of NVP in the BMI/NVP systems increases the reactive conversions almost linearly. © 2004 Wiley Periodicals Inc. J Appl Polym Sci 94: 2407‐2416, 2004     

BCE/BMI/EP共聚体系动力学研究

采用双酚A型氰酸酯(BCE),双马来酰亚胺(BMI)和两种环氧树脂(EP)制备了BCE/BMI/EP共聚体系,用傅里叶变换红外法对BCE/BMI/EP体系的共聚反应进行了反应动力学研究,分别对在150,180和200℃下的固化反应历程进行了红外跟踪,测得了各个反应单体的功能基团在不同温度下的转化率曲线,求得共聚反应的活化能为65.66 kJ/mol。     

双马来酰亚胺树脂的共聚改性

介绍一种由双马来酰亚胺、取代双马来酰亚胺和二烯丙基双酚A共聚所得树脂体系,重点研究了树脂的性能如溶解性、粘度特性、凝胶时间和反应性等以及固化树脂的力学性能和耐热性等。     

Rheological study of crosslinking and gelation in bismaleimide/cyanate ester interpenetrating polymer network

In searching for high performance polymer resins that have a combination of low dielectric constant and loss, high temperature resistance, ease of being processed, and other desirable properties, an interpenetrating polymer network (IPN) based on cyanate ester (CE) and 2,2′‐diallylbisphenol A (DBA) modified bismaleimide resin (BMI) was prepared via prepolymerization followed by thermal curing. This work discusses the use of multiple waveform rheological technique to investigate the crosslinking and gelation behavior of this resin system at various temperatures. The gel point can be accurately determined from a single experiment using this technique. At the point of gelation, both the storage modulus (G′) and loss modulus (G″) of the IPN follow a similar power law equation with oscillation frequency used in the rheological measurement. Both the relaxation exponent n, a viscoelastic parameter related to the cluster size of the gel, and gel strength S, related to the mobility of the crosslinked chain segments, were determined via a curve fitting method. Both n and S were found to be temperature dependent in this BMI/DBA–CE IPN system. The apparent activation energy of gelation or curing reaction was found to be approximately 47.6 kJ/mol. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2437–2445, 2001     

SiO_2/CE/BMI复合材料固化反应动力学的研究

通过示差扫描分析法(DSC)研究了SiO2/氰酸酯树脂(CE)/含有活性稀释剂的双马来酰亚胺树脂(BMI)复合材料的固化动力学,求得其固化工艺参数为:凝胶温度87.13℃,固化温度137.27℃,后处理温度203.58℃;用Kissinger法和Ozawa法求得其固化动力学参数为:表观活化能6.692kJ/mol,反应级数1.493,Arrhenius方程中的频率因子11.9445s-1。与CE/BMI体系对比表明,SiO2的加入可以降低CE/BMI体系的活化能,使其固化反应可以在较低温度下进行。     

Preparation and characterization of soluble bismaleimide‐triazine resins based on asymmetric bismaleimide

A series of bismaleimide‐triazine resins (EBT) were prepared from 2‐(4′‐maleimido)phenyl‐2‐(4′‐maleimidophenoxyl)phenylbutane (EBA‐BMI) and 2,2‐bis(4‐cyanatophenyl)propane (BADCy). The resins show attractive processability with good solubility in low boiling point solvents and wide processing temperature windows. Introduction of diallylbisphenol A (DBA) can decrease the curing temperature of EBT resins that the curing exothermic peak temperature shifted from 291 to 237 °C as the content of DBA increased from 0 to 20%. The curing condition influenced the thermal properties of the cured EBT resins. The glass transition temperature increased as the curing temperature and curing time increased. The cured EBT resins show high glass transition temperature up to 352 °C, high thermal stability with 5% weight loss temperature over 405 °C, low coefficient of thermal expansion about 45 to 52 ppm/°C, and high storage modulus up to 2.6 GPa at 250 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44519.     

Kinetics modeling of carbon‐fiber‐reinforced bismaleimide composites under microwave and thermal curing

This article focuses on the analysis of the curing kinetics of carbon‐fiber‐reinforced bismaleimide (BMI) composites during microwave (MW) curing. A nonisothermal differential scanning calorimetry (DSC) method was used to obtain an accurate kinetic model. The degree of curing, chemical characterization, and glass‐transition temperature of the resin and composites cured by thermal and MW heating were analyzed with DSC, Fourier transform infrared spectroscopy, and dynamic mechanical analysis. The experimental results indicate that MW accelerated the crosslinking reaction of the BMI resin and had different effects on the reaction processes, especially for the glass‐transition temperature and chemical bonds. However, the curing reaction rate of the BMI resin decreased when the carbon fibers were added to the BMI resin during thermal and MW curing. According to the experimental results, the curing kinetic model of the BMI composite was used to provide a theoretical foundation for MW curing analysis. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43770.     

Modeling the curing kinetics for a modified bismaleimide resin using isothermal DSC

The kinetics of curing for a modified bismaleimide (BMI) resin was investigated to ascertain a suitable cure model for the material. The resin system used in this study was composed of 4,4′‐bismaleimidodiphenylmethane (BMIM) and 0,0′‐diallyl bisphenol A (DABPA, DABA). The BMIM was the base monomer and the DABPA was the modified agent. A series of isothermal DSC runs provided information about the kinetics of cure in the temperature range 170–220°C. Regardless of the different temperatures, the shape of the conversion curves was similar, and this modified BMI resin system underwent an nth‐order cure reaction. Kinetic parameters of this BMI resin system, including the reaction model, activation energy, and frequency factor, were calculated. From the experimental data, it was found that the cure kinetics of this resin system can be characterized by a first‐order kinetic model. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3338–3342, 2004     

Curing kinetics of diglycidyl ether of bisphenol‐A (n = 0) using an iron‐containing porphyrin as cross‐linking agent

The curing reaction of a system consisting of a diglycidyl ether of bisphenol‐A (n = 0) and hemin (a protoporphyrin IX containing an iron ion and an additional chloride ligand) was studied with a differential scanning calorimeter. A maximum value of ?488.3 ± 8.4 J g^?1 was obtained for the enthalpy of the reaction. The kinetics of the process was studied by the isothermal method, observing that it obeys to Kamal's model, with an overall reaction order equal to 3. From the dependence of the kinetic constant with temperature, the activation energy, activation enthalpy, and activation entropy were determined. The ratio of the kinetic constants associated to the autocatalytic and nth order terms of the reaction rate, together with the thermodynamic activation parameters suggest a trend to the autocatalytic path mechanism with increasing temperatures. This study demonstrates that macrocycles can be used as cross‐linking agents for curing epoxy resins and that when metallomacrocycles are used, metal ions can be introduced into the network structure. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3972–3978, 2013     

Thermal degradation study of interpenetrating polymer network based on modified bismaleimide resin and cyanate ester

Interpenetrating polymer networks (IPNs) based on different ratios of a modified bismaleimide resin (BMI/DBA) and cyanate ester (b10) have been synthesized via prepolymerization followed by thermal curing. A systematic thermal degradation study of these new BMI/DBA‐CE IPN resin systems was conducted by thermogravimetric analysis at different heating rates both in N₂ (thermal stability) and in air (thermal‐oxidative stability). The cured BMI/DBA‐CE IPN resin systems show excellent thermal stability, which could be demonstrated by 5% weight loss temperature (T_5%) ranging between 409 and 423 °C, maximum decomposition rate temperature (T_max) ranging between 423 and 451 °C, and the char yields at 800 °C ranging from 37% to 41% in nitrogen at a heating rate of 10 °C min^?1. The apparent activation energy associated with the main degradation stage of the cured BMI/DBA‐CE IPN resin systems was determined using the Kissinger method. The obtained results provide useful information in drawing correlation between thermal properties and structure. © 2003 Society of Chemical Industry     

Fluorescence method using labeled chromophores to study the curing kinetics of a polyurethane system

A fluorescence method using labeled chromophores to study the curing kinetics of a polyurethane (PU) system was developed. A PU system based on fluorescent‐labeled hexamethylene diisocyanate and a polyol (polyether/polyester) was cured at different temperatures (25, 40, 50, and 65°C). The fluorescent response from the 5‐dimethylaminonaphtalene‐1‐(N‐2‐aminoethyl)sulfonamide and 4‐methacryloylamino‐4′‐nitrostilbene moieties chemically bonded to the PU system was monitored as a function of the curing time. With the fluorescence data, it was possible to model the kinetics of the curing process. Methods based on the fluorescence intensity ratio and the first moment of the fluorescent band emission were applied to determine the degree of curing of the PU system. In addition, it was possible to calculate an apparent activation energy for the curing process, and a value of 17 kJ/mol was obtained. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2992–3000, 2002     

动态DSC法研究BMI改性酚醛树脂固化反应动力学

采用非等温DSC(差示扫描量热)法研究BMI(双马来酰亚胺)改性PF(酚醛树脂)体系的固化动力学,借助升温速率-温度(β-T)外推法和红外光谱(FT-IR)跟踪固化反应过程,确定了BAN(BMI改性PF)体系的固化工艺和固化动力学参数。结果表明:BAN的固化工艺为"120℃/2 h→140℃/2 h→160℃/2 h→180℃/2 h",后处理工艺为220℃/3 h,BAN固化体系的动力学参数是表观活化能Ea=123.4 kJ/mol、频率因子A=1.96×1012s-1和反应级数n=1.05;根据n级动力学反应模型求解出该树脂的反应动力学方程,其计算值与试验值基本吻合,说明该模型能较好描述BAN的固化反应过程。     

Moisture curing kinetics of isocyanate ended urethane quasi‐prepolymers monitored by IR spectroscopy and DSC

The study of the kinetics of the curing of isocyanate quasi‐prepolymers with water was performed by infrared spectroscopy and differential scanning calorimetry. The influence of the free isocyanate content, polyol functionality, and of the addition of an amine catalyst (2,2′‐dimorpholinediethylether) in the reaction kinetics and morphology of the final poly(urethane urea) was analyzed. A second‐order autocatalyzed model was successfully applied to reproduce the curing process under isothermal curing conditions, until gelation occurred. A kinetic model‐free approach was used to find the dependence of the effective activation energy (E_a) with the extent of cure, when the reaction was performed under nonisothermal conditions. The dependence of E_a with the reaction progress was different depending on the initial composition of the quasi‐prepolymer, which reveals the complexity of the curing process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Rice husk ash filled natural rubber. III. Role of metal oxides in kinetics of sulfur vulcanization

In preceding investigations the overall rate and apparent activation energy for the vulcanization process were calculated for natural rubber compounds, assuming that vulcanization follows first‐order kinetics. It was observed that the addition of white rice husk ash (WRHA) increased the rate of crosslinking and lowered the apparent activation energy more profoundly than commercial fillers, precipitated silica (Zeosil‐175) and carbon black (N762), with a conventional vulcanization system. In this work, a specific model for the vulcanization process accelerated by N‐cyclohexylbenzothiazole sulfenamide was used to investigate the real role of WRHA in crosslink formation. Cure studies were carried out at 150°C, and the kinetics constants were evaluated. In relation to the other fillers, WRHA seems to develop catalytic activity, resulting in a positive effect on the specific rate of crosslink formation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1519–1531, 2003     

Studies on the cure kinetics of chitosan‐glutamic acid using glutaraldehyde as crosslinker through differential scanning calorimeter

The curing of chitosan‐glutamic acid with glutaraldehyde as curing agent in the presence of chlorpheniramine maleate (CPM) is carried out with the help of differential scanning calorimeter (DSC). The effect of concentration of chitosan and percentage of crosslinker on the curing of chitosan‐glutamic acid is studied at a heating rate of 5°C/min. Cure kinetics are measured by the DSC using scans from 25 to 220°C at four different heating rates (3, 5, 7, and 10°C/min) and it is observed that the crosslinking of chitosan‐glutamic acid is an exothermic process which results in a positive peak in the DSC thermograms. The activation energy (E_α) is determined by Flynn, Wall, and Ozawa method for curing of the samples. An increase in activation energy (E_α) is observed with the extent of conversion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effects of storage aging on the cure kinetics of T700/BMI prepregs for advanced composites

The effects of room temperature aging on the cure kinetics of a bismaleimide (BMI) matrix prepreg have been characterized by different time and storage conditions. The study has focused on the stability of BMI matrix carbon fiber prepregs, when exposed to controlled environmental conditions before being used in composite manufacturing. The effects of aging on reactivity, glass transition temperature, and process window have been investigated by differential scanning calorimetrer through dynamic and isothermal tests. A theoretical kinetic model for epoxy matrix prepregs, developed in previous studies, has been applied to the cure of both aged and virgin BMI matrix. The model is able to satisfactorily describe the effect of processing variables such as temperature and degree of cure during the curing of the composite under different conditions (curing temperature and heating rate). The effects of diffusion‐controlled phenomena on the cure kinetics, associated with changes in glass transition temperature as a function of the degree of cure, have been taken into account in the formulation of an nth‐order kinetic model. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers