Synthesis and characterization of aqueous (polyurethane/aromatic polyamide sulfone) copolymer dispersions from castor oil

Aqueous dispersions of castor oil-based polyurethane (PUCO)/aromatic polyamide sulfone (APAS) block copolymers (PUCO-co-APAS) were successfully synthesized via a copolymerization reaction. PUCO was prepared by an emulsion polymerization process in four steps, namely isocyanate-terminated prepolymer preparation step (PUCO_NCO), neutralization step, chain extension step and dispersion step, using castor oil (CO), toluene diisocyanate (TDI), dimethylol propionic acid (DMPA) and ethylene diamine (EDA) as a chain extender. APAS was prepared by a polycondensation reaction between bis(4-aminophenyl)sulfone (in molar excess) and terephthaloyl chloride to produce amino-terminated APAS. Three PUCO-co-APAS were prepared via a copolymerization reaction between the amino-terminated APAS and isocyanate-terminated PUCO_NCO prepolymer. APAS, PUCO and PUCO-co-APAS copolymers were characterized using FTIR, ¹H NMR, particle size distribution (PSD), zeta potential (ZP), thermal analysis (DSC and TGA) and GPC. The effect of the copolymerization process on the thermal, chemical, physical and mechanical properties of PUCO films was studied. The obtained results revealed that the mean particle size of PUCO decreased from 80 nm to 46–49 nm after the copolymerization process. Additionally, narrower size distribution was obtained by the copolymerization process. However, the molecular weight increased with increasing the amount of APAS in the copolymer chains. The copolymerized samples showed better thermal stability than PUCO as a result of the stronger hydrogen bonds and the rigid aromatic groups introduced by APAS in the copolymeric chains.     

聚酰胺酸/环氧树脂的固化动力学研究

在高沸点的DMAc(N,N′-二甲基乙酰胺)溶液中制备了环氧树脂/聚酰胺酸(EP/PAA)共混物。采用非等温DSC(差示扫描量热)法研究了EP/PAA体系的固化动力学及其固化工艺,并通过Kissinger法、Ozawa法和Crane法计算出该体系的动力学参数。结果表明:该EP/PAA体系的固化条件为"100℃/2 h→120℃/2 h",后处理工艺为140℃/2 h;其平均表观活化能为61.15 kJ/mol,反应级数为0.95,近似于1级反应;升温速率不同时,EP/PAA固化体系的频率因子(A)、峰温时的反应速率常数(KP)均不相同。     

水性环氧树脂固化剂研究进展

介绍了水性环氧固化剂改性原理、改性方法以及国内外水性环氧固化剂的研究进展。     

含癸二酰胺的共聚酰胺固化剂的合成及性能

用癸二酸和二聚酸与多胺共缩聚合成了含癸二酰胺的共聚酰胺固化剂,研究了癸二酸加入量对合成固化剂胺值、粘度的影响,及对固化剂与环氧树脂E-44混合体系力学性能的影响。加入癸二酸后,树脂粘度有大幅度的下降,但癸二酸的加入量超过5%以后,合成的共聚酰胺固化剂粘度逐渐增加;产物的胺值与E-44的固化体系的固化度、拉伸强度和剪切强度都随癸二酸加入量的提高而提高。其凝胶时间缩短,比较发现,当癸二酸加入量为二聚酸加入量的20%时,与四乙烯五胺合成的固化剂各方面性能较好,其体系的粘度为二聚酸性聚酰胺的80%左右。在酸组分不变的情况下,混合体系的裂解温度随胺分子质量的增加而下降,失重率则相反。     

Cure behavior of epoxy resin containing castor oil and cashew nut shell liquid and its derivative

The cure behavior of epoxy resin with a conventional amide‐type hardener (HD) was investigated in the presence of castor oil (CO), cashew nut shell liquid (CNSL), and cashew nut shell liquid–formaldehyde resin (CFR) with dynamic differential scanning calorimetry (DSC). The activation energy of the curing reaction was also calculated on the basis of nonisothermal DSC thermograms at various heating rates. A one‐stage curing was noted in the case of epoxy resin filled with CO, whereas the epoxy resin with CNSL and CFR showed a two‐stage curing process. A competitive cure reaction was noted for the epoxy resin/CNSL(or CFR)/HD blends. In the absence of HD, CFR showed lower values of curing enthalpy than that of CNSL. The activation energy of epoxy resin curing increased with increasing CNSL and CFR loading. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

超支化聚酰胺酯增韧增强环氧树脂的性能研究

以四氢甲基苯酐(MeTHPA)为固化剂,超支化聚酰胺酯(HBP)为增韧剂,制备了HBP/MeTHPA/环氧树脂(EP)固化体系。采用红外光谱(FT-IR)对HBP/MeTHPA/EP复合体系的固化机理进行了研究,并讨论了不同含量的HBP对固化体系热力学性能的影响。实验结果表明,HBP的加入会促进体系的固化反应;当w(HBP)=10%时力学性能最佳,冲击强度和拉伸强度分别增加了142.71%和34.44%,而玻璃化转变温度(Tg)有所下降,储能模量在玻璃态时均明显提高。     

Influence of two-step process and of different stoichiometric ratios on morphologies generated in castor oil epoxy resins

Phase separation during polymerization was studied in a model system consisting of a diepoxide based on diglycidyl ether of bisphenol A (DGEBA), variable amounts of ethylenediamine (EDA) and the mass of castor oil (CO) necessary to obtain a mass fraction equal to 0-15 in a final system where the stoichiometric ratio of amine to epoxy equivalents, r, was equal to 1. A two-step polymerization process was performed by curing first a system with r = 0-5, during variable times before phase separation, and then carrying the system to r = 1. Thermodynamic analysis of samples with different r values led to a linear relationship between the Flory-Huggins interaction parameter and r. The concentration (P) and average size (D?) of dispersed-phase particles followed opposite trends, i.e. P increased while D? decreased, when either r was increased or the time of curing in the first step of a two-step process was decreased. This was explained by assuming that the competition between nucleation and growth was determined by the viscosity at the cloud point, η_cp. Low values of η_cp favoured growth over nucleation and led to fewer but larger particles.     

桐油制备C_(21)二元酸聚酰胺固化剂合并生物柴油

由桐酸甲酯和丙烯酸经Diels-Alder加成反应制备了C21二元酸(TMAA),并以此为原料制备了C21二元酸聚酰胺固化剂。TMAA的最佳合成条件为:反应温度180℃,反应时间3 h,桐酸甲酯和丙烯酸的质量比为1∶0.247,阻聚剂对苯二酚的加入量为丙烯酸质量的1%,产率为85%。TMAA聚酰胺固化物和C36二聚酸聚酰胺固化物相比,具有更高的弹性模量、弯曲强度、弯曲模量、压缩强度、压缩模量和玻璃化温度。但由于其碳链短,断裂伸长率较低。从加成反应物中可分离出未反应的脂肪酸甲酯,分离条件:180~240℃/0.267 kPa,得率(相对于未反应脂肪酸总质量)85%。性能测试表明该脂肪酸甲酯与生物柴油(BDF)性能相似,可作为液体燃料使用。     

蓖麻油型单组分聚氨酯发泡胶的制备

研究了以蓖麻油、聚醚多元醇、聚酯多元醇、PAPI为原料合成系列发泡单组分聚氯酯胶粘剂的工艺,研究了各因素对预聚体的合成、产品性能及贮存稳定性的影响。结果表明,异氰酸酯指数为28～30,蓖麻油为多元醇总质量的40％,预聚催化剂为T-12,固化催化剂为吗啉类和LX-1,溶剂为乙酸乙酯和二氧甲烷,在70-80℃下反应3h,得到符合建材工业要求的产品。     

环氧胶粘涂层冲蚀磨损特性研究

研究了环氧胶粘涂层在不同的磨料粒度和浆体浓度下冲蚀磨损时耐磨性能的变化,对比了T-31、低分子聚酰胺两种固化剂和粉煤灰、有机蒙脱土两种填料对环氧胶粘涂层性能的影响,探讨了纳米粒子在环氧胶粘涂层中的作用,推荐了纳米环氧胶粘涂层的最佳配方。     

Properties of alkoxysilane castor oil synthesized via thiol-ene and its polyurethane/siloxane hybrid coating films

We developed a new silanized castor oil (MSCO) composed of castor oil and 3-mercaptopropyl trimethoxy silane via thiol-ene coupling (TEC). This MSCO was used as a functional polyol in the preparation of a series of bio-based polyurethane/siloxane (SiPU) hybrid coatings through reactions with different castor-oil-and-isophorone-diisocyanate (IPDI) ratios. The SiPU films exhibited better mechanical and thermal properties than castor oil-based coatings without MSCO. The cross-linked structure of the obtained hybrid materials was confirmed by Fourier transform infrared (FTIR) spectroscopy, whereas the morphologies and surface roughness of the hybrid-coating films were observed by scanning electron microscopy (SEM). A slight phase separation was observed in the obtained hybrid materials. The introduction of a silica network can reduce the surface energy of the obtained hybrid materials. The thermal stability of the obtained hybrid materials increases with increasing Si content. The obtained hybrid materials can be applied in coatings as a result of these characteristics, and this study provides an alternative method of preparing hybrid materials from renewable sources.     

Effects of composition of hardener on the curing and aging for an epoxy resin system

Different mixture ratios of Shell Epon 828 (based on diglycidyl ether of bisphenol A, DGEBA) and Shell EPI‐CURE 3046 (based on triethylenetetramine, TETA) were evaluated under different environments of isothermal curing at 80°C in DSC, room temperature curing in air, and aging in water at 45°C. The curing reactions were monitored using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and infrared spectroscopy (IR). It was shown that the initial curing rate increased with the amount of hardener. However, the epoxy groups in samples with excess hardener were prone to reaction with primary amines located at the ends of TETA molecules, resulting in a less dense epoxy network. During aging in water at 45°C, significant effects of water on the postcure and the increased water absorption with an increase of hardener amount were observed. The DMA results show that the samples with hardener around stoichiometric composition have the greatest storage modulus while curing in air environment. However, the samples with hardener much less than stoichiometric composition have greater storage modulus under aging in water at 45°C. in water at 45°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 580–588, 2006     

One-component epoxy adhesive for repair of cell phone board

The development of a one-component epoxy adhesive for cell phone board repair was described. The most important goal of this study is to obtain long storage stability in conjunction with the curing reaction process at a relatively low temperature of 95 °C. Bisphenol-A type, bisphenol-F type, and NBR-based epoxy resins were used as the basic resins. Dicyandiamide (DICY) was used as a curing agent, and 2-methylimidazole (2MI) was used as an accelerator. 2MI was encapsulated using a copolymer of methacrylic acid and dodecyl methacrylate to achieve latent curing performance. After mixing the epoxy resin with DICY and encapsulated 2MI, this curing system showed excellent storage stability with almost no viscosity increase for 2 months at 20 °C, and full curing was achieved at 95 °C for 50 min. We determined the optimum formulation of the epoxy adhesive for adhesion of a cell phone board after the measurement of physical properties.     

γ-异氰酸酯基丙基三乙氧基硅烷改性环氧树脂/聚酰胺膜层的吸水性

为了提高环氧/聚酰胺(EP/PAI)树脂体系的耐水性,在环氧树脂的主链上成功地接枝了γ-异氰酸酯基丙基三乙氧基硅烷(IPTES)。用差示扫描量热法(DSC)测试了两种树脂在氯化钠溶液中浸泡不同时间后的玻璃化温度(Tg)。采用旋转法在铝合金表面形成IPTES改性EP/PAI和未改性EP/PAI树脂保护膜层。用电化学阻抗谱(EIS)法测定了IPTES改性与未改性两种EP/PAI树脂膜层在氯化钠溶液中浸泡不同时间的电容大小,由此计算出两种膜层在浸泡不同时间吸水的体积百分数,并分析了水在两种膜层中的吸附行为。结果发现,改性树脂的Tg随浸泡时间增长而增加,改性树脂膜层的吸水性显著降低,水在改性树脂膜层中的扩散不遵从菲克第二定律。     

Electrochemical impedance studies of corrosion protected surfaces covered by epoxy polyamide coating systems

Electrochemical impedance spectroscopy (EIS) was used to study the corrosion behavior of different types of commercial quality epoxy polyamide dry coatings on mild steel, with thickness between 150 and 250 μm, which were previously weather accelerated in a wet chamber. The following data were established on the basis of impedance curves and corresponding equivalent circuits: the coating capacity that relates to the coating dimension, the pore resistance that represents conductive paths through the pores, and Warburg coefficients, which are the measure of ion diffusion through the coating. EIS data were compared with a criterion in the European standard, and samples were classified on the basis of their quality, also receiving a final ranking by summing-up all the individual rankings. Suggestions have been made, namely that the use of anticorrosive active pigments is obsolete, when the thickness of the coatings exceeds 200 μm.     

A simple and rapid polarimetric method for quantitative determination of castor oil

A simple and rapid polarimetric method is developed for quantitation of adulteration of castor oil in edible oils such as cottonseed, coconut, mustard, olive, palm, peanut, rice bran, safflower, soybean, and sunflower. The method is based on the optical activity of ricinoleic acid (12-hydroxy octadecenoic acid), a major constituent of castor oil. There is a good correlation between optical rotation and castor oil content in admixtures above 5%. Highly colored and viscous oils interfere in the measurement of optical activity. The method is highly specific and cost-effective. No solvents and chemicals are required for the analysis because no sample processing is involved in the present method.     

Synthesis of polysiloxane‐type multifunctional flame retardant and its application in epoxy systems

Polymethyl(3‐glycidyloxypropyl)siloxane (PMGS) was synthesized as a flame‐retardant additive, which were cocured with diglycidyl ether of bisphenol‐A (DGEBA) using 4,4′‐diaminodiphenylsulfone as a curing agent. The structure of PMGS was confirmed through Fourier transform infrared and ¹H‐NMR spectra. The cured products were characterized with dynamic mechanical thermal analysis, thermogravimetric analysis, and oxygen index analyzer. With PMGS incorporated, the cured epoxy resin showed better thermal stability, higher limited oxygen index, and higher char yield. At moderate loading of PMGS, the storage modulus and glass transition temperature of the cured epoxy resin based on neat DGEBA were obviously improved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

室温固化环氧树脂灌封胶的制备

选用奇士增韧剂QS-070N做为增韧剂,合成具有较高活性的环氧树脂为甲组分,自制的固化剂为乙组分,2-乙基-4-甲基咪唑促进剂为丙组分制成了室温固化环氧树脂灌封胶,该胶机械性能、电性能优良,可广泛应用于航空航天等高科技领域。     

聚酰胺热熔胶性能研究及其应用

概述了近年新开发的聚酰胺热熔胶的特性、分类及特点,并对其应用及最新进展和发展趋势作了总结。