Conversion analysis of acrylated hyperbranched polymers UV‐cured below their ultimate glass transition temperature

The photo‐curing behavior of reactive blends of dipentaerythritol penta/hexaacrylate (DPHA) with an acrylated hyperbranched polyester and an acrylated hyperbranched polyether was investigated by means of photo differential scanning calorimetry. The chemical conversion data was analyzed using an autocatalytic model with close attention paid to the influence of composition, UV intensity, and vitrification. The autocatalytic model was found to be relevant to describe autoacceleration and diffusion controlled reaction stages, as long as the polymers were not vitrified. It was shown that the reaction order and the autocatalytic exponent were independent of UV intensity, whereas the rate constant showed strong intensity dependence, and the maximal conversion showed weak intensity dependence. A criterion for vitrification onset was proposed as the occurrence of a third stage in the conversion process. The ultimate conversion was found to be 0.16 higher than the conversion at vitrification for all investigated multifunctional acrylates independent of composition and UV intensity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2366–2376, 2007     

Using mixture experimental design to study the effect of multifunctional acrylate monomers on UV cured epoxy acrylate resins

An epoxy acrylate resin was synthesized and the resin was used along with different multifunctional acrylate monomers, i.e. trimethylol propane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), 1,6-hexanedioldiacrylate (HDDA). The effect of the chemical structure of the monomers on some of the physical–mechanical properties of the resins and their cured films, such as viscosity, T_g, hardness and scratch resistance was studied. To minimize the number of experiments, mixture method was used as an appropriate tool for experimental design.     

不同固化剂对环氧树脂玻璃化温度影响的分子动态模拟研究

提出了一个分子动态模拟方法研究环氧树脂玻璃化转变温度(Tg)随固化剂结构变化。首先,建立了固化环氧树脂的一些简单分子模型;然后是一个分子动态模拟(MD)被重复执行。用模拟得到的数据作V-T关系曲线,用曲线上的转折点确定Tg的值。该模拟值与计算值有很好的吻合,尽管与实验值有较大的偏差,固化剂对Tg的影响可以用MD模拟定性得到。所提出的方法对于开发具有提高固化效果的固化剂有潜在的意义。     

Effect of post-cure on the glass transition temperature and mechanical properties of epoxy adhesives

The effects of post-curing and cure temperature on the glass transition temperature, T _g, and the mechanical properties of epoxy adhesives were studied. T _g was measured by a dynamic mechanical analysis apparatus developed in-house and the mechanical properties of the adhesives (yield strength, Young’s modulus and failure strain) were measured by a tensile machine. The relationships between T _g and mechanical performance under various post-cure conditions were investigated. The curing process was the same for all tests, consisting of an initial stage performed at different temperatures followed by cooling at room temperature. Three sets of specimens were considered, sharing the same initial cure process, but with a different post-curing procedure. In the first set, the specimens were only subjected to a curing process; in the second set, the specimens were subjected to a curing process followed by a post-cure performed at a temperature below the T _g of the fully cured network, T _g∞; and in the third set, the specimens were subjected to a curing process followed by a post-cure performed at a temperature above the T _g∞. When post-cured at a temperature above T _g∞, the mechanical and physical properties tend to have a constant value for any cure temperature.     

Effect of external electric field on morphologies and properties of the cured epoxy and epoxy/acrylate systems

In this article, the influences of the external electric field exerted to the curing epoxy and epoxy/acrylate systems on their cured microstructures and macroscopic performances were investigated by means of morphological investigation and some characteristic analyses. Epoxy and epoxy/acrylate (an interpenetrating polymer network) systems were subjected to the action of the alternating electric field during the curing process. The changes in the nanolamellae microstructure in the cured epoxy and the nanoellipsoid microstructure in the cured epoxy/acrylate systems resulting from the electric field treatment were observed using atomic force microscopy. Dynamic mechanical analysis showed that the external electric field treatment made the low and high relaxation peaks shift to the lower and higher temperatures, respectively. Thermogravimetric analysis implied that the curing reactions of the epoxy systems with the aid of the external electric field resulted in some negative influences on their thermal stability. The dielectric measurements demonstrated that the electrical properties of the epoxy system for vacuum pressure impregnation insulation of the high-voltage electric machines could be much improved with the aid of the external electric field. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

玻璃纤维对高温固化环氧胶的增强作用研究

研究了高温固化环氧胶胶层状况不良对粘接强度的影响,采用了填充玻璃纤维的方法,运用合理的粘接实施过程,有效地解决了胶料高温流失和固化过程小分子气体残留的问题,显著提高了粘接强度。此方法可适用于刚性与脆性材质的粘接,也可应用于流动性较好的其他胶种。     

Preparation,characterization, and thermal properties of controllable metal–imidazole complex curing agents for epoxy resins

A series of complexes incorporating the epoxy–imidazole adduct of phenyl glycidyl ether with 2‐ethyl‐4‐methylimidazole (PGE‐EMI), has been prepared with the acetato and chloro transition metal salts of Mn, Co, Ni, Cu, Zn, and Ag. These complexes have been characterized using spectroscopic methods (IR, UV‐Vis, ¹H‐ and ¹³C‐NMR, where appropriate) and their thermal stabilities have been determined using elevated temperature NMR techniques. These high‐temperature NMR results indicated that the chloro complexes studied (of Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) exist in equilibrium (i.e., they dissociate reversibly in a solution of dimethylsulphoxide, DMSO, at elevated temperatures), while the corresponding acetato complexes dissociate irreversibly. For the silver complexes, thermogravimetric analysis (TGA) was used to monitor the dissociation, showing that the weight loss recorded was consistent with the dissociation of the metal salt to liberate the PGE–imidazole ligand. The thermal stabilities of the metal complexes were influenced by changing both the transition metal (e.g., from Mn to Zn) and varying the anion (e.g., from acetate to chloride). From ¹H‐NMR analysis, a decrease of ca. 10°C was observed in the thermal dissociation of the acetato complexes when compared with the chloro complexes, showing that the series of PGE‐EMI complexes with acetate anions is less thermally stable than the corresponding chlorides. This finding suggests that these PGE‐EMI complexes may be modified to accommodate their use in a variety of different curing schedules when used to cure epoxy resins. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 201–217, 2000     

The role of network architecture on the glass transition temperature of epoxy resins

A series of epoxy networks were synthesized in which the molecular weight between crosslinks (M_c) and crosslink functionality were controlled independent of the network chain backbone composition. The glass transition temperature (T_g) of these networks was found to increase as M_c decreased. However, the rate at which T_g increased depended on crosslink functionality. The dependency of M_c on T_g is well described by two models, one based on the concept of network free volume while the other model is based on the principle of corresponding states. Initially, neither model could quantitatively predict the effect of crosslink functionality in our networks. However, our tests indicated that both the glass transition and the rubbery moduli of our networks were dependent on M_c and crosslink functionality, while the glassy state moduli were independent of these structural variables. The effect of crosslink functionality on the rubbery modulus of a network has been addressed by the front factor in rubber elasticity theory. Incorporation of this factor into the glass transition temperature models allowed for a quantitative prediction of T_g as a function of M_c and crosslink functionality. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 387–395, 1997     

聚氨酯丙烯酸酯/环氧丙烯酸酯分散体系的制备

用水性聚氨酯丙烯酸酯改性环氧丙烯酸酯,制备了聚氨酯丙烯酸酯/环氧丙烯酸酯分散体系。随着分散体中聚氨酯丙烯酸酯浓度的增加,体系稳定性增加,当其浓度达到30%时,可制得稳定的分散体系。这种分散体系可作为一种紫外光固化水性涂料,其涂膜的耐磨性、柔韧性都比环氧丙烯酸酯涂膜增强,而硬度变化不大。     

含有环氧基的丙烯酸酯的合成及其固化物的研究

采用脂肪族环氧树脂(EP-664)与丙烯酸(AA)合成了低黏度的含有环氧基的丙烯酸酯(AEG),该反应性酯类化合物与双酚A型环氧树脂(E-44、EP-6002)共混,以甲基六氢苯酐(MeHHPA)为固化剂,并分别采用三级胺和2-乙基-4-甲基咪唑(2E4MZ)为促进剂,通过混合物黏度曲线的变化与其固化物力学性能的测试,研究了AEG含量对环氧树脂体系黏度的变化和固化物力学性能的影响。结果显示,AEG的添加可以有效地降低树脂体系的黏度,25℃下混合体系黏度仅为300～600mPa·s;其固化物的力学性能随AEG含量的增加先增加后降低,具有最大值。三级胺固化体系的力学性能明显优于2E4MZ固化体系,当w(AEG)为20%时,固化物的综合力学性能最好。     

环氧丙烯酸酯预聚物的合成研究进展

综述了环氧丙烯酸酯预聚物的合成与改性。介绍了合成原理,环氧树脂、催化剂、阻聚剂对合成的影响;分别用醇、酸（酸酐）、半酯及聚氨酯4类物质对环氧丙烯酸酯改性,从而得到不同性能的环氧丙烯酸酯预聚物。     

环氧有机硅油改性丙烯酸树脂的合成及性能

以偶氮二异丁腈为引发剂,通过丙烯酰氧基硅油与丙烯酸酯类单体的自由基共聚合反应,同时环氧828与丙烯酸共聚侧链羧基进行开环反应,合成以乙醇为主要溶剂的单相均匀牛顿型环氧有机硅油改性丙烯酸树脂。并对树脂涂膜的稳定性及硬度、耐水煮性,附着力等性能进行了研究。得到的树脂具有良好的热储稳定性,颜料广泛润湿性。环氧有机硅油改性丙烯酸树脂涂膜具有光泽高、硬度好、丰满度高、玻璃附着力强、耐水煮性好与透明性高等优异性能,适用于高档玻璃烤漆。     

Blends of epoxy resins and polyphenylene oxide as processing aids and toughening agents 2: Curing kinetics,rheology, structure and properties

The curing behaviour, chemorheology, morphology and dynamic mechanical properties of epoxy ? polyphenylene oxide (PPO) blends were investigated over a wide range of compositions. Two bisphenol A based di‐epoxides ? pure and oligomeric DGEBA ? were used and their cure with primary, tertiary and quaternary amines was studied. 4,4′‐methylenebis(3‐chloro‐2,6‐diethylaniline) (MCDEA) showed high levels of cure and gave the highest exotherm peak temperature, and so was chosen for blending studies. Similarly pure DGEBA was selected for blending due to its slower reaction rate because of the absence of accelerating hydroxyl groups. For the PPO:DGEBA340/MCDEA system, the reaction rate was reduced with increasing PPO content due to a dilution effect but the heat of reaction were not significantly affected. The rheological behaviour during cure indicated that phase separation occurred prior to gelation, followed by vitrification. The times for phase separation, gelation and vitrification increased with higher PPO levels due to a reduction in the rate of polymerization. Dynamic mechanical thermal analysis of PPO:DGEBA340/MCDEA clearly showed two glass transitions due to the presence of phase separated regions where the lower T_g corresponded to an epoxy‐rich phase and the higher T_g represented the PPO‐rich phase. SEM observations of the cured PPO:DGEBA340/MCDEA blends revealed PPO particles in an epoxy matrix for blends with 10 wt% PPO, co‐continuous morphology for the blend with 30 wt% PPO and epoxy‐rich particles dispersed in a PPO‐rich matrix for 40wt% and more PPO. © 2014 Society of Chemical Industry     

紫外光固化环氧丙烯酸酯涂料的制备及耐蚀性能研究

以E-51环氧树脂和丙烯酸为原料合成出光敏性环氧丙烯酸酯低聚物,制备了不同组成的紫外光固化涂料.合成产物的红外光谱分析结果表明,光敏性碳碳双键基团被引入到环氧树脂结构中;固化后涂层的红外表征结果表明,碳碳双键C=C的特征吸收峰消失,涂层固化较完全.在无水乙醇、5%NaOH和5%H2SO4溶液中的浸泡实验以及在3.5%NaCl溶液中的电化学阻抗谱测量结果表明,涂层具有较好的耐蚀性,其耐蚀性随着涂料中环氧丙烯酸酯含量的增加,呈先提高后下降的趋势.当环氧丙烯酸酯含量为40%,二缩三丙二醇双丙烯酸酯含量为50%时,所得涂层的耐蚀性最佳.     

环氧型丙烯酸酯橡胶的硫化

通过硫化曲线评定,选用苯甲酸铵作硫化剂环氧丙烯酸酯橡胶低温胶进行硫化。结果表明,共聚单体中甲基丙烯酸缩水甘油酯用量为２％－３％,苯甲酸铵用量为１．５份时,经胶的力学性能最好。二段硫化对硫胶的力学性能几乎无影响。     

Studies on the cure kinetics and networks properties of neat and polydimethylsioxane modified tetrafunctional epoxy resins

The cure kinetics of tetrafunctional epoxy resins with three different backbone structures and their modification by polydimethylsioxane (PDMS) were studied by means of differential scanning calorimetry with dynamic approach. The development of epoxy networks was characterized by dynamic viscoelastic measurements. Results showed that all the epoxy resins obeyed the autocatalytic reaction mechanism with a reaction order of about 3. Epoxy resin with softer aliphatic backbone demonstrated a higher cure reactivity and stronger tendency towards autocatalysis, as well as lower crosslinking density. The PDMS‐modified epoxy resins showed higher early cure reactivity and a lower crosslinking density due to the plasticization and restriction effect of the dispersed PDMS phase, respectively. Based on cure kinetics and dynamic viscoelastic results, the α_m was found to be an effective precursor for describing the developing of epoxy networks during the course of cure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

紫外光固化环氧丙烯酸树脂的合成

环氧丙烯酸（ＥＡ）树脂在辐射固化领域中是一种重要的感光树脂,其中双酚Ａ型环氧树脂的应用最为广泛。本文着重研究了该种树脂的合成工艺,讨论了原料投料比、反应温度、催化剂及操作方法等因素对树脂性能的影响,并通过正交试验确定了最佳反应条件。     

Probing the temperature sensitivity of induction time in latent cure epoxy resins

Two dynamic viscosity datasets for epoxy resins cured at temperatures between 100 and 150 °C were re‐analyzed to compare the interpretation of gel times and activation energies using two mathematical models. © 2012 Society of Chemical Industry     

光固化环氧丙烯酸酯体系的增韧研究

在癸二酸增韧环氧丙烯酸酯(GEA)的基础上,研究了通过加入聚氨酯丙烯酸酯(PUA),改善环氧丙烯酸酯紫外光固化材料的柔韧性,同时避免强度的较大损失。结果显示,对于癸二酸改性的环氧丙烯酸酯(癸二酸与环氧树脂的摩尔比为0.3),当GEA∶PUA∶稀释剂:光引发剂(质量比)为61.6∶15.4∶20∶3时,PUA共混改性的GEA光固化体系具有良好的综合性能,此时拉伸强度为8.84 MPa,断裂伸长率为109%,柔韧性为1 mm。     

含氟单体对环氧丙烯酸酯树脂性能的影响

以甲基丙烯酸甲酯（MMA）、甲基丙烯酸缩水甘油酯（GMA）、丙烯酸六氟丁酯（F6BA）为原料,采用溶液聚合法制备了含氟环氧丙烯酸酯共聚物。采用FT-IR、¹³C NMR 、DSC和GPC等手段对共聚物的化学结构、玻璃化转变温度和分子量及其分布的分析表明：产物是含氟类环氧丙烯酸酯共聚物,玻璃化转变温度随含氟单体用量的增大而降低,分子量分布较窄,分布指数在1.35～1.65之间。采用JC2000C1静滴接触角/界面张力仪考察了共聚物膜的表面能,发现随着共聚物中氟单体含量的增加,表面能下降,当氟单体含量达到20％时,其表面能降低到38.27 mJ·m^-2,吸水率随氟单体用量的增大从18.72％下降至4.55％,耐酸碱性能明显提高,涂膜铅笔硬度从3H下降至2H。