双环戊二烯酚型环氧树脂的固化反应研究

研究了ＤＣＰＤ酚环氧树脂与酸酐及胺类固化剂的固化反应活性。通过ＤＳＣ热分析方法表征了ＤＣＰＤ酚环氧树脂与甲基六氢苯酐（ＭeHHPA)及４,４′－二氨基二苯甲烷（ＤＤＭ）的固化反应过程,测定了反应热焓,并分析了固化温度、时间及固化剂结构等对ＤＣＰＤ酚环氧树脂凝胶时间及固化度的影响,探讨了温度、时间对ＤＣＰＤ酚环氧树脂固化反应活性的影响。     

Vitrification effect during the reaction injection molding (RIM) process of epoxy resin

Vitrification occurs during the reaction injection molding (RIM) of epoxy resin, and the curing reaction rate is reduced as the T_g of the reacting mixture exceeds or approaches the local reaction temperature inside the mold cavity. The effect will be manifested in the distribution of the glass transition temperature across the thickness direction of the molded product. The reaction kinetic equation which includes the vitrification term in the form of the WLF equation is used in the computer simulation of the epoxy RIM process and the effect of the vitrification is shown by comparing with models with no vitrification considerations.     

Vitrification and further structural relaxation in the isothermal curing of an epoxy resin

Isothermal curing of an epoxy resin based on diglycidyl ether of bisphenol A, using a hardener derived from phthalic anhydride, has been performed at curing temperatures between 30 and 130°C. Samples were cured isothermally at various intervals of time and analyzed by differential scanning calorimetry (DSC), the glass transition temperature T_g, and the conversion degree being determined by the residual enthalpy technique. The vitrification phenomenon and a further structural relaxation process, occurring at curing temperatures (T_c) lower than the maximum T_g (109°C), at which T_g equalizes T_c, have been studied at curing temperatures between 30 and 100°C. The structural relaxation process is analyzed by the endothermic peak that appears superposed on T_g in dynamic DSC scans. The area of this peak (Q) is a measure of the recovery enthalpy, and thus of the extent of the relaxation process. This process begins at higher curing times (t_c) when T_c decreases because the vitrification of the system starts later. Both the enthalpy recovery (Q) and the temperature of the endothermic peak (T_m) increase with the annealing time (t_a), calculated as the difference between t_c and the time in which vitrification occurs, and tend to have a limiting value due to the fact that the system loses mobility when the free volume decreases during its asymptotic approach toward the metastable equilibrium state. Furthermore, the dependence of Q and T_m on t_a at different T_c shows that the relaxation process in partially cured resins depends on the conversion degree of the system and consequently on the crosslinking density of the network.     

水性环氧树脂固化反应的研究

通过测定凝胶时间,利用红外光谱仪、差示扫描量热仪等对水性环氧树脂的固化反应进行了研究,并根据K issinger和Ozawa方法分别求得水性环氧树脂体系固化反应的表观活化能。结果表明,凝胶时间随着环氧与胺氢物质的量比的增大而增加,且环氧与胺氢物质的量比为1∶1时较好。环氧基特征吸收峰的强度随着固化反应时间的延长明显变弱,且固化4 h后,环氧的特征峰几乎全部消失。水性环氧体系固化的初始温度、峰值温度和终止温度随着升温速率的增加,均向高温方向移动,用Kissinger和Ozawa法求得水性环氧树脂固化的表观活化能分别为27.35 kJ/mol、32.77 kJ/mol,表明体系的表观活化能很低,固化反应很容易进行。     

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。     

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。     

改性双氰胺衍生物固化环氧树脂的研究

针对双氰胺固化环氧树脂时固化温度过高的缺点,从自行设计并合成的一系列改性双氰胺中筛选出一种,将其与环氧树脂复配制成单组分潜伏性环氧树脂胶粘剂,利用差示扫描量热法(DSC)和红外光谱法(FT-IR) 对单组分环氧树脂固化体系的固化反应进行了分析和研究。结果表明,改性双氰胺与双氰胺相比,具有较高的活性,显著降低了固化反应的反应温度;所配制的单组分环氧树脂胶粘剂具有较长的贮存期和良好的固化性能。     

端胺基聚氨酯／环氧树脂胶粘剂的固化过程特点研究

采用差示扫描量热法(DSC)研究了两种含有柔性链和刚性结构单元的端胺基聚氨酯(ATPU-2和 ATPU-1．5)对环氧树脂E-44固化反应过程特点的影响。结果表明,ATPU在胶粘剂中的含量对固化放热特征、 固化放热量和固化程度有显著的影响,随着ATPU的增加,固化放热量增加,固化度亦增加。     

腰果酚缩醛胺与环氧树脂固化反应的研究

研究了腰果酚缩醛胺(PCD)固化剂加成固化环氧树脂(EP)聚合物的合成,考察了不同因素对该聚合物性能的影响。结果表明:当m(PCD):m(EP)=30:70时,PCD/EP聚合物的综合性能最佳;此时,PCD/EP聚合物对基材表面的附着力为1级,其柔韧性为1mm,拉伸强度为43.52MPa,压缩强度为85.09MPa,断裂伸长率为8.9%,热变形温度为125℃,硬度为2H(铅笔法),并具有优异的耐化学介质性能。     

环境温度对环氧—聚氨酯固化反应的影响

论述了环氧树脂,环氧－醇胺加成物,环氧－沥青混合物与聚氨酯加成物（MDI、TDI）固化剂混合后在不同环境下的粘度变化曲线,及促进剂,缓聚剂等对固化反应的影响。     

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。     

新型环氧固化剂的合成及固化动力学研究

介绍了2步法合成1,4-双(2,4-二氨基苯氧基)苯(14BDAPOB)的方法,并将其用作环氧树脂固化剂。采用非等温差示扫描量热法(DSC)对酚醛环氧树脂/14BDAPOB的固化过程进行了研究,并利用Kissinger、Crane和Arrhenius方程对该固化反应进行了动力学分析,求得了体系的固化动力学参数;测定了体系的拉伸剪切强度。结果表明,体系的活化能为66.97 kJ/mol,反应级数为0.90;经14BDAPOB固化后的酚醛环氧体系拉伸剪切强度可达21.3 MPa。     

纳米二氧化钛对环氧树脂固化反应的影响

采用非等温DSC研究了纳米二氧化钛改性环氧树脂体系(EP)的固化动力学,采用Flynn-Wall-Ozawa和Vyazovkin非线性等转化率方法(NLV)法分析了固化活化能与转化率的关系,利用Kissinger和Crane方程研究了固化动力学参数,根据不同升温速率下DSC固化反应曲线确定了固化工艺参数。结果表明,纳米二氧化钛促进了环氧树脂的固化,降低了固化反应的活化能,但没有改变环氧树脂的固化机理。     

环氧树脂/苯乙烯-马来酸酐共聚物体系固化动力学研究

用示差扫描量热仪(DSC)对环氧树脂/苯乙烯-马来酸酐共聚物/甲基咪唑体系的固化反应过程进行了分析,并用Kissinger和Ozawa方法分别求得固化反应的表观活化能ΔE为58.27 kJ/mol和64.93 kJ/mol;根据Crane理论计算得到该体系的固化反应级数n=0.85,为该环氧树脂体系的固化工艺确定提供理论依据。     

环氧树脂固化促进剂的研究

以甲苯二异氰酸酯(TDI)和3-二甲氨基丙胺为单体、甲苯为溶剂,合成了环氧树脂(EP)的固化促进剂——甲苯-2,4-二(N,N′-二甲氨基丙脲)。为了验证自制促进剂的性能,以EP/双氰胺/促进剂为基体,并辅以填料、增韧剂、沉淀硫酸钡和流平剂等助剂,制备了粉末涂料。结果表明:制备促进剂的最佳工艺条件为n(TDI)∶n(3-二甲氨基丙胺)=1∶1.8、3-二甲氨基丙胺/甲苯溶液的滴加时间为1.5 h;当w(促进剂)=2.0%、固化温度为160℃时,粉末涂料的固化时间为6.5 min、胶化时间约100 s,并且其硬度、附着力和柔韧性俱佳,完全满足生产要求和使用要求。     

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     

硫脲改性物对环氧树脂固化促进作用的研究

对硫脲的热稳定性、硫脲对环氧树脂的固化能力及硫脲与脂肪胺和芳香胺的反应活性进行了研究。结果表明,硫脲170℃分解,其不能单独作环氧固化剂,硫脲与脂肪胺的反应活性大于与芳香胺的反应活性。研究了在硫脲改性胺类环氧固化剂反应中,硫脲反应程度和用量对改性固化剂反应活性的影响。结果表明在保证改性固化剂为液态的条件下,硫脲反应程度尽可能低较好,n二乙烯三胺∶n硫脲为1.5∶1为宜。     

微波固化碳纤维/环氧树脂胶的研究

介绍了微波固化热固性树脂的原理和特点,利用微波炉设备和选择的一种较好微波吸收剂,探讨了微波固化工艺。研究表明,利用微波固化环氧胶时,不仅固化时间短,而且剪切强度优于加热固化。     

低共熔点芳胺固化环氧树脂动力学研究

采用低熔点的间苯二胺(m-PDA)对新型固化剂长链柔性芳香胺(LCDA)进行物理共混改性,得到了1种低共熔点的芳胺环氧固化剂。n(m-PDA)∶n(LCDA)=1∶1时,混合物具有低共熔温度为50.9℃。研究了该低共熔点芳胺与环氧树脂(E-51)的固化行为,根据Melak方法和Kissinger方法确定了体系的固化动力学模型及固化动力学参数。结果表明:该体系的固化动力学模型符合n级固化反应方程,其表观活化能△E为54.49 kJ/mol,频率因子A为7.28×105和反应级数n为0.813。此外,运用外推法得体系起始固化温度Tgel为110℃,恒温固化温度Tcure为150℃,后处理温度Ttreat为185℃,还对体系的固化工艺进行了探讨。     

ToF‐SIMS investigation of epoxy resin curing reaction at different resin to hardener ratios

Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and principal components analysis (PCA) were used to analyze diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of bisphenol F (DGEBF) epoxy resin blend cured with isophorone diamine (IPD) hardener at different resin to hardener ratios. The aim was to establish correlations between the hardener concentration and the nature and progress of the crosslinking reaction. Insights into the cured resin structure revealed using ToF‐SIMS are discussed. Three sets of significant secondary ions have been identified by PCA. Secondary ions such as C₁₄H₇O⁺, CHO⁺, CH₃O⁺, and C₂₁H₂₄O₄⁺ showed variance related to the completion of the curing reaction. Relative intensities of C_xH_yN_z⁺ ions in the cured resin samples are indicative of the un‐reacted and partially reacted hardener molecules, and are found to be proportional to the resin to hardener mixing ratio. The relative ion intensities of the aliphatic hydrocarbon ions are shown to relate to the cured resin crosslinking density. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008