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力为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。     

聚氨酸粉末涂料固化行为的研究

动用ＤＳＣ方法研究了聚氨酯粉末涂料固化时的基本过程及原理。得出的结论表示－ＯＨ／－ＮＣＯ摩尔比（文中简称树脂／固化剂摩尔比）在０．６３～０．６７时,固化反应有良好的平均速率;催化剂可以明显促进固化反应,但不改变反应的动力学模型。     

环氧树脂潜伏性体系固化反应的DSC研究

用差式扫描量热仪对ＢＰＥＡ－２／环氧树脂潜伏性固化体系的固化反应进行了分析。了固化剂的用量,固化温度,固化时间及升温速度时固化反应的热效应和固化度的影响。结果表明：ＢＰＥＡ－２潜伏性固化 用量以ｍ（环氧）：ｍ（固化剂）＝１００：９－１０）为宜。     

用DSC研究环氧树脂／二酰肼粘料体系的固化过程

利用差示扫描量热法（ＤＳＣ）研究了环氧树脂（ＥＰ）／癸二酸二酰肼（ＳＤＨ）粘料体系中固化剂含量和促进剂含量对固化反应和粘料体系热性能的影响，确定了固化工艺温度有固化反应动力学参数。结果表明：当ＥＰ／ＳＤＨ的摩尔比为１：１／５，促进剂含量为０．４％时，固化产物的耐热性较好，该体系的固化反应表观活化能（Ｅ）为９１．９０ＫＪ／ｍｏｌ，反应级数（ｎ）为０．９５，频率因子（ＩｎＡ）为２２．０９Ｓｅｃ＾－１。     

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。     

常温固化自乳化型水性环氧固化剂的制备及性能研究

以聚乙二醇、环氧树脂E20、间苯二甲胺（MXDA）为原料、过硫酸钾为催化剂，合成了一种非离子型常温固化自乳化型水性环氧固化剂。系统优化了反应温度、时间、催化剂用量以及原料配比对固化剂性能的影响，利用红外光谱对固化剂进行结构表征，测试了基于该固化剂乳化固化环氧树脂E44所得涂层的性能。结果表明：当过硫酸钾用量占环氧树脂和聚乙二醇总量的0.75%、n（环氧树脂）∶n（聚乙二醇）∶n(MXDA)=1∶1∶4，反应温度为180℃、时间为4 h时，所得涂膜的机械性能、耐腐蚀性能优异。     

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。     

用差示扫描量热法研究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环氧封端酚酞聚芳醚腈（简称Ｅ－ＰＣＥ）中固化剂类型对Ｅ－ＷＣＥ树脂固化反应温度、反应热的影响,结果表明,固化剂与Ｅ－ＰＣ Ｅ树脂反应的活性为ＭＤＡ＞ＤＤＥ＞ＤＤＳ;Ｅ－ＰＣＥ／ＤＤＳ体系的最低固化反应温度为１６３．２℃,固化反应峰顶温度为２２８,１℃,固化反应表观活化能为８１．２７ｋＪ／ｍｏｌ,固化反应级数为０．９０。     

固化剂

环氧树脂组成用N-苯基-对苯撑二胺固化剂；环氧树脂组成物用固化剂；含酚固化促进剂及低温固化环氧树脂组成物；硼酸酯固化促进剂及贮存稳定的环氧树脂组成物；热同性树脂用固化催化剂的制备。     

含三嗪结构环氧树脂的固化反应动力学研究

研究了邻甲酚醛环氧树脂／苯代三聚氰胺酚醛树脂的固化反应机理,邻甲酚醛环氧树脂（o—CFER）被固化剂苯代三聚氰胺酚醛树脂（BPR）固化,采用非等温扫描方法研究环氧树脂固化反应,用来确定其固化反应动力学参数以及最佳固化工艺条件。用差示扫描量热仪（DSC）对邻甲酚醛环氧树脂固化体系的固化反应过程进行了分析。采用不同升温速率,用Kissinger方法求得体系固化反应的表观活化能△E=63．6kJ／mol,根据Crane理论计算得到该体系的固化反应级数n=0．899。固化反应起始温度、峰值温度、终止温度分别为Tio=102．95℃、Tpo=132．16℃、Tpf=166．6℃,为确定苯代三聚氰胺酚醛树脂作为固化剂的固化反应条件提供了一定的理论依据。     

Kinetic analysis of curing behavior of diglycidyl ether of bisphenol A with imidazoles using differential scanning calorimetry techniques

The curing kinetics and mechanisms of diglycidyl ether of bisphenol A (DGEBA) using imidazole (H‐NI) and 1‐methyl imidazole (1‐MI) as curing agents are studied with differential scanning calorimetry (DSC) under isothermal (90–120°C) and dynamic conditions (50–250°C). The isothermal DSC thermograms of curing DGEBA with H‐NI and 1‐MI curing agents show two exothermic peaks. These peaks are assigned to the processes of adduct formation and etherification. These results indicate that there is no difference in the initiation mechanism of 1‐unsubstituted (H‐NI) and 1‐substituted (1‐MI) imidazoles in the curing reaction with epoxy resin. A kinetic analysis is performed using different kinetic models. The activation energies obtained from DSC scanning runs using the Ozawa and Kissinger methods are similar and in the range of 75–79 and 76–82 kJ/mol for DGEBA/H‐NI and DGEBA/1‐MI systems, respectively. These values compare well with the activation energies obtained from isothermal DSC experiments using the autocatalytic method (74–77 kJ/mol). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2634–2641, 2006     

Effect of microencapsulated curing agents on the curing behavior for diglycidyl ether of bisphenol A epoxy resin systems

Microcapsules containing a curing agent, 2‐phenyl imidazole (2PZ), for a diglycidyl ether of bisphenol A (DGEBA) epoxy resin were prepared by a solid‐in‐oil‐in‐water emulsion solvent evaporation technique with poly(methyl methacrylate) (PMMA) as a polymeric wall. The mean particle size of the microcapsules and the concentration of 2PZ were about 10 μm and nearly 10 wt %, respectively. The onset cure temperature and peak temperature of the DGEBA/2PZ–PMMA microcapsule system appeared to increase by nearly 30 and 10°C, respectively, versus those of the DGEBA/2PZ system because of the increased reaction energy of curing. The former could take more than 3 months at room temperature, whereas the latter was cured after only a week. The values of the reaction order (a curing kinetic parameter) for DGEBA/2PZ and DGEBA/2PZ–PMMA microcapsules were quite close, and this showed that the curing reactions of the two samples proceeded conformably. The curing mechanism was investigated, and a two‐step initiation mechanism was considered: the first was assigned to adduct formation, whereas the second was due to alkoxide‐initiated polymerization. The glass‐transition temperature of DGEBA/2PZ was 165.2°C, nearly 20°C higher than the glass‐transition temperatures of DGEBA/2PZ–PMMA microcapsules and DGEBA/2PZ/PMMA microspheres, as determined by differential scanning calorimetry measurements. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Nonisothermal cure kinetics of DGEBA with novel aromatic diamine

The effect of the molar ratio of diglycidyl ether of a bisphenol‐A based epoxy (DGEBA) and synthesized 4‐phenyl‐2,6‐bis(4‐aminophenyl)pyridine (PAP) as curing agent during nonisothermal cure reaction by the Kissinger, Ozawa, and isoconversional equations was studied. The cure mechanism was studied by FTIR analysis. Kinetic analysis of the curing reaction of DGEBA at two different concentrations (42 and 32 phr) of the curing agent was studied by using DSC analysis. With an increasing PAP content, the pre‐exponential factor increased by increasing collision probability between epoxide and primary or secondary amine groups in noncataltyic or catalytic modes. The activation energy also increased because of the increasing content of crosslink density. The activation energies obtained from three equations were in good agreement. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3076–3083, 2007.     

Novel Epoxy Curing Agents from Epoxy Resin Based Dialdehyde Derivative

Abstract

A series of epoxy based curing agents were synthesised by the reaction of dialdehyde derivative 1, 1′-(1 -methylethylidene) di[4-{ 1-(1-imino-4-benzaldehyde)-2-propanolyloxy}] benzene of epoxy resin with a different aromatic diamines. The dialdehyde derivative was synthesised by the reaction of epoxy resin (DGEBA) with 4-amino benzaldehyde (4-ABA) in presence of triethyl amine (1% by wt. Of resin) as a catalyst. All this curing agents were characterised by their number average molecular weight (Mn), elemental analyses and infrared spectrophotometry (IR). As produced, polymers may act as a epoxy curing agent, the thermal characteristics of the synthesised PK-epoxy resin system were investigated by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).     

Enzyme‐catalyzed copolymerization of oxiranes with dicarboxylic acid anhydrides

Ring‐opening copolymerizations of the oxiranes glycidyl phenyl ether (GPE) and diglycidyl ether of bisphenol A (DGEBA) with a dicarboxylic acid anhydride [methyl hexahydrophthalic anhydride, nadic anhydride, maleic anhydride (MA), or itaconic anhydride (IA)] were carried out with the lipases Candida cylindracea (CCL), Lipozyme TL‐IM (LIM), and Novozyme 435 (N435) as catalysts. The CCL‐catalyzed reaction of DGEBA with MA or IA (at a 1:2 molar ratio) at 80°C resulted in only partial curing. We monitored the reactions by Fourier transform infrared spectroscopy and by following the changes in the intensities of carbonyl stretching frequencies of the anhydride and ester groups. The reactivity of the oxirane group in GPE was higher than that in DGEBA; this may have been due to the higher viscosity of DGEBA. The reactivities of the enzymes for the copolymerization of the oxiranes and dicarboxylic acid anhydride were in the order LIM > CCL > N435. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 697–704, 2005     

Curing Behavior of Epoxy Resin Using Controllable Curing Agents Based on Nickel Complexes

Summary: The curing reaction kinetics and mechanism of the diglycidyl ether of bisphenol A (DGEBA) with three complexes of Ni(II) with diethylentriamine (Dien), Pyrazole (Pz) and Pyridine (Py) as ligands have been studied using differential scanning calorimetry (DSC). The curing reaction was characterized by high cure onset and peak maximum temperatures. The kinetics of the curing reaction were evaluated using the Ozawa method. The average values of activation energy for the three nickel complexes increased in the order: Dien‐based curing agent > Pz‐based curing agent > Py‐based curing agent. Three main curing mechanisms (catalytic, complex cation and free ligand polymerization path) have been proposed depending on the cure temperature. It was also shown that the cure kinetics of DGEBA with Dien‐ and Py‐based complexes could be described by the Sestak‐Berggren equation. The water absorption, chemical resistance and thermal stability of the thermosets were also studied. The results showed that the thermoset obtained with the Py‐based complex was more thermally stable than those obtained with the other two curing agents.

Activation energy versus conversion plots for the epoxy systems studied.     

Preparation and properties of soybean oil–based curing agents for epoxy resin

In order to improve the flexibility properties of conventional epoxy resin, two novel soybean oil–based curing agents were synthesized. The curing agent obtained from the reaction between epoxy soybean oil and ethylene diamine was named EEDA, and another curing agent derived from epoxy soybean oil and isophorone diamine was named EIPDA. Several techniques were used to systematically investigate the effects of the structure and content of the two curing agents on the properties of the cured products. The Fourier transform infrared analysis demonstrated that epoxy resin reacted with soybean oil–based curing agents. The differential scanning calorimetry analysis showed that the curing process between diglycidyl ether of bisphenol‐A (DGEBA) and soybean oil–based curing agents only had an exothermic peak. Thermogravimetric analysis indicated that the cured DGEBA/EIPDA system was more stable than the DGEBA/EEDA system below 300 °C. Mechanical tests and Shore D hardness tests suggested that excessive EEDA greatly enhanced the toughness of cured products because of the introduction of aliphatic chains.© 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44754.     

环氧树脂低温快速固化剂的合成及性能研究

以苯酚、多聚甲醛、二乙烯三胺、硫脲为单体,以DMP-30为促进剂,合成了环氧树脂低温快速固化剂.分析了反应温度、反应时间以及各材料用量对环氧树脂固化剂性能的影响,并进一步考察了固化剂与环氧树脂最佳用量比.在( 110±2)℃下反应2.5 h,苯酚、多聚甲醛、二乙烯三胺、硫脲之比为1∶1.25∶1.3∶1.1,且DMP-...     

Studies on epoxy/calcium carbonate nanocomposites

The article describes the preparation of epoxy‐calcium carbonate nanocomposites using diaminodiphenyl sulfone (DDS) as a curing agent. The curing behavior of diglycidyl ether of bisphenol‐A (DGEBA) (1 mol) in the presence of varying amounts of nanocalcium carbonate was investigated by differential scanning calorimetry (DSC) using stoichiometric amounts of diaminodiphenyl sulphone (0.5 mol) as curing agent. The amount of calcium carbonate (～ 44 nm) was varied from 2% to 10% (w/w). In the DSC scans of these samples, a broad exothermic transition due to curing was observed in the temperature range of 110–335°C. As expected, heat of curing decreased with increasing amount of nanocalcium carbonate; however it did not affect the curing characteristics, thereby indicating that the filler did not hinder the curing reaction. Thermal stability of DGEBA in the presence of varying amounts of nano‐CaCO₃ after isothermal curing [(i.e., by heating in an air oven at 80°C (1 h), 100°C (1 h), 120°C (1.5 h), and 180°C (4 h)] was evaluated by thermogravimetry. All the samples were stable upto 350°C, and char yield at 800°C increased with increasing amount of nanocalcium carbonate. Rectangular bars were prepared by mixing DGEBA, DDS, and varying amounts of CaCO₃ using silicone mold. The nanocomposites were characterized by X‐ray, scanning electron microscopy (morphological characterization), and dynamic mechanical analysis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Loss of Curing Agent During Thin Film (Droplet) Curing of Thermoset Material

Recently, it has been reported by our group and others^1.2 that loss of curing agent is encountered during the curing of small droplets or thin films of amine cured epoxies. In our earlier study³ results were reported on loss of curing agent in small droplets used in conducting the rnicrobond, single fiber test for determination of interfacial shear strength (ISS). It was reported that use of a volatile curing agent (meta-phenylene diamine (m-PDA) with DGEBA resin) resulted in increasing amounts of curing agent being lost (as measured by T₈ of the cured droplets) with decreasing droplet size during the processing procedure. Droplets smaller than 150 micrometers were seen to lose up to 40% of the curing agent leading to alteration of the mechanical properties of the droplet and, therefore, causing measured values of ISS to be exceedingly low. Use of a less volatile curing agent (Jeffamine 700, a polyether diamine, Texaco Specialty Chemicals) in combination with DGEBA resin produced results which indicated that loss of curing agent was not occuring. This study was undertaken to show the relationships between film (or droplet) size and the amount of curing agent lost (during the processing) for three different aminecured epoxy systems.