Neutron reflectivity investigation of bis-amino silane films

Neutron reflectivity is used to elucidate the morphology of silane films deposited on silicon wafers, and the response of these films to vapors of swelling solvents. Bis-silyl functional silanes studied here have six hydrolyzable groups and are believed to be more crosslinked than tri- and tetra-functional analogs. The enhanced crosslinking leads to better barrier properties in anti-corrosion applications. In this study, solvent swelling is used to assess the degree of condensation and the crosslink density in bis-[trimethoxysilylpropyl]amine (bis-amino) films. Nitrobenzene swells the films but does not react chemically with the films. The results show that bis-amino silane films are highly condensed, with a nitrobenzene-depleted layer near the silicon substrate. D₂O both swells (at 25°C and 80°C) and chemically alters the films (at 80°C). The reflectivity data upon exposure to D₂O vapors at 80°C are consistent with exchange of the amino proton (¹H) with deuterium (D). A hydrophilic layer is postulated at both the air and substrate interfaces.     

Strength of Epoxy/Glass Interfaces after Hygrothermal Aging

The stability of epoxy/glass interfaces subjected to hygrothermal aging was assessed using a fracture-mechanics approach. An epoxy system consisting of diglycidyl ether of bisphenol F cured with 2-ethyl-4-methyl-imidazole was bonded to borosilicate glass adherends that were treated with various types of adhesion promoters to provide a variety of interfaces. Adhesive strength was measured under dry, as-processed conditions and as a function of exposure time to an 85°C/85% relative humidity (RH) environment. As expected, the strain-energy-release rate, G _c , dropped significantly with aging time for the bare epoxy/glass interface. The drop in G _c is assumed to be due to a loss of interfacial forces. The use of two silane-based adhesion promoters, 3-aminopropyltriethoxysilane (APS) and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (ECH) resulted in improved adhesive strength both before and after hygrothermal aging. The improvement in adhesive strength can be explained by the introduction of chemical bonds at the interface. The drop in G _c is assumed to be due to a loss of interfacial forces and hydrolysis of siloxane bonds. In addition to the use of organosilane-based adhesion promoters, a series of polyhydroxyaminoethers (PHAE) thermoplastic adhesive resins was also investigated as potential adhesion promoters. It was found that 2% PHAE in Dowanol® PM, a hydroxyl-group-containing solvent, was the best system for the PHAE-based adhesion promoters. Interestingly, both the acetic acid concentration in the solvent and maleic anhydride content in the PHAE resin were shown to affect the adhesive strength.     

Strength of Epoxy/Glass Interfaces after Hygrothermal Aging

The stability of epoxy/glass interfaces subjected to hygrothermal aging was assessed using a fracture-mechanics approach. An epoxy system consisting of diglycidyl ether of bisphenol F cured with 2-ethyl-4-methyl-imidazole was bonded to borosilicate glass adherends that were treated with various types of adhesion promoters to provide a variety of interfaces. Adhesive strength was measured under dry, as-processed conditions and as a function of exposure time to an 85°C/85% relative humidity (RH) environment. As expected, the strain-energy-release rate, G_c, dropped significantly with aging time for the bare epoxy/glass interface. The drop in G_c is assumed to be due to a loss of interfacial forces. The use of two silane-based adhesion promoters, 3-aminopropyltriethoxysilane (APS) and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (ECH) resulted in improved adhesive strength both before and after hygrothermal aging. The improvement in adhesive strength can be explained by the introduction of chemical bonds at the interface. The drop in G_c is assumed to be due to a loss of interfacial forces and hydrolysis of siloxane bonds. In addition to the use of organosilane-based adhesion promoters, a series of polyhydroxyaminoethers (PHAE) thermoplastic adhesive resins was also investigated as potential adhesion promoters. It was found that 2% PHAE in Dowanol® PM, a hydroxyl-group-containing solvent, was the best system for the PHAE-based adhesion promoters. Interestingly, both the acetic acid concentration in the solvent and maleic anhydride content in the PHAE resin were shown to affect the adhesive strength.     

Plasma polymerization coating of silica fillers for Epoxy Molding Compounds (EMCs)

Silica fillers for Epoxy Molding Compounds (EMCs) were modified via plasma polymerization coating of acrylonitile, acrylic acid and dimethyl phosphite with RF plasma (13.56 MHz). The resulting samples were characterized by DSC, FT-IR and contact angle measurements. EMC samples were prepared from silica fillers, biphenyl epoxy resin, phenol novolac and triphenyl phosphine, and cured at 175°C for 4 h. Flexural strength of the EMC samples was evaluated in a 3-point bending mode with an Instron 5567 at a crosshead speed of 1 mm/min both at RT and 250°C, and failure surfaces were analyzed by SEM. Some samples were exposed to 121°C, 2 atm pressure and 100% RH for 12, 24 and 32 h, and then to 250°C for 10 min prior to testing at RT. Plasma polymer coating of silica with acrylonitrile greatly improved the flexural strength of EMC at RT as well as at 250°C, followed by acrylic acid and dimethyl phosphite. Exposing EMC samples to 121 °C, 2 atm pressure and 100% RH for 32 h decreased the flexural strength by 13% when the silica was coated with acrylonitrile plasma polymer, compared to the 21% decrease in the control sample. Plasma polymer coating of silica also increased the Tg of the EMC, and lowered water absorption and CTE in the rubbery region. Therefore, enhanced properties by plasma polymer coating of silica with acrylonitrile or acrylic acid can be attributed to nitrile or carboxylic acid groups, as confirmed by FT-IR, which can react with epoxy groups in the base resin, as evidenced by DSC analysis.     

Enhancement of Corrosion Performance of Epoxy Coatings by Chemical Modification With GPTMS Silane Monomer

In this paper, commercial epoxy resin was chemically modified by different amounts of 3-glycidoxypropyltrimethoxysilane (GPTMS) monomer using an organotin compound as catalyst, aiming to improve the anti-corrosion performance of epoxy coatings on 2024-T3 aluminum alloy substrate. Electrochemical impedance spectroscopy (EIS) was used to evaluate the barrier properties against water permeation and protectiveness of silane-modified epoxy coatings. The results showed that all the modified coatings presented higher barrier performance and better corrosion performance than pure epoxy coating, which were characterized by higher charge transfer resistance (R _ct) and lower double-layer capacitance (C _dl) at the electrolyte/metal interface. The improvements in corrosion performance and wet adhesion of modified epoxy coatings were also observed by the Machu test and boiling water test, respectively. Interestingly, it was found that the glass-transition temperature (T _g) of silane-modified epoxy coatings decreased only slightly during immersion in 3.5 wt% NaCl solution, in contrast with pure epoxy coating, which was observed to decrease significantly after water permeation. The corrosion performance of epoxy coatings was, thus, improved when the amount of chemically grafted silane monomer increased in the content range investigated in the present work.     

The Miscibility of Novel Bisphenol-Propylene Epoxy Resin With Liquid NBR

A novel kind of bisphenol-type epoxy resin with a vinyl side-chain was developed and its miscibility behavior with liquid nitrile-butadiene rubber (NBR) was investigated. The diglycidyl ether of bisphenol propylene (DGEBP) was prepared by the condensation of phenol with acrolein in the presence of an acid catalyst and the subsequent epoxidization with epichlorohydrin (ECH). The structures of the bisphenol and corresponding epoxy resin were characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectral analyses and the epoxy value was determined to be 0.34 mol/100 g by titration. The mixture of DGEBP with the liquid NBR containing diglycidyl ether of bisphenol acetone (DGEBA) was prepared and cured with diaminodiphenylmethane (DDM). The miscibility and morphology of the mixture system were studied by dynamic mechanical thermal analysis (DMTA) and transmission electron microscopy (TEM), respectively. The cured mixture of DGEBP/NBR/DDM exhibited good miscibility and, therefore, no separation, along with a transparent appearance at rubber contents of 10 wt% and 30 wt%. For cured DGEBP/DGEBA/NBR/DDM systems at 20 wt% rubber content, the dispersed rubber phase and rubber particles were not observed by DMTA or TEM at DGEBP content above 40 wt%. The DMTA plot showed a single peak related to the glass transition temperature (T _g) which decreased with increasing DGEBP content. The appearance of the system varied from transparent to opaque and the rubber separated from the epoxy matrix to form two phases when the DGEBP content decreased. The T _g values of the rubber- and epoxy-rich phases were strongly dependent on the DGEBP content in the mixed system. The miscibility of epoxy resin with liquid NBR can be altered by varying the ratio of DGEBP to DGEBA.     

水性环氧地坪涂料的研制

选用低相对分子质量的液体环氧树脂作为甲组分,采用适宜的水性胺固化剂、颜填料、及助剂制成乙组分,制备了性能优良的水性环氧地坪涂料,可广泛用于各类室内工业地坪涂装。     

水性环氧防腐涂料的研制

采用低相对分子质量的液态环氧树脂和具有乳化作用的水性环氧固化剂为主要成膜物质,配以适宜的颜填料、助剂、去离子水,配制成具有防腐性能良好的水性环氧防腐涂料。着重讨论了树脂基料对漆膜防腐性能的影响。     

自乳化水性环氧涂料的研究

制备一种潜伏型的非离子自乳化环氧固化剂,用FT-IR验证了固化剂的结构并表征了其物理性质。用该固化剂制备出了粒径较小的水性环氧乳液及性能优异的涂料。讨论了含水量对乳液黏度、电导率的影响;分析了水性环氧涂料的固化机理,并建立了固化模型;考察了影响水性环氧涂料性能的因素。结果表明:利用潜伏型非离子自乳化环氧固化剂制备的涂料具有适宜的表干时间,优异的柔韧性、附着力、铅笔硬度、耐冲击性和热学性能。确定了制备自乳化水性环氧涂料的条件:最佳多元胺为二乙烯三胺,含水量为40%~50%,固化温度为40~50℃,胺氢与环氧基物质的量比为0.8∶1~1.0∶1,促进剂用量为1.0%~1.5%。     

水性环氧涂膜的亲水改性研究

采用水溶性高分子聚丙烯酰胺(PAM)作为接枝改性剂,对水性环氧涂料进行亲水改性,分析了亲水改性的机理,采用傅里叶变换红外光谱仪对改性前后所得涂膜的结构进行表征,证实了接枝反应的存在,用液滴状分析仪(DSA)测量涂膜的接触角,用Neumann法计算涂膜的表面能,并研究了聚丙烯酰胺溶液用量、固化剂用量和聚丙烯酰胺溶液的质量浓度对涂膜亲水性的影响。     

The Effect of Accelerated Weathering on the Mechanical Properties of Alkali Treated Hemp Fibre/Epoxy Composites

In this study, 65 wt% aligned untreated long hemp fibre/epoxy (AUL) and aligned alkali treated long hemp fibre/epoxy (AAL) composites cured at 70°C using compression moulding were subjected to accelerated weathering using an accelerated weathering chamber with UV-irradiation and water spray at 50°C for four different time periods (250, 500, 750 and 1000 h). After accelerated weathering, tensile strength (TS), flexural strength, Young's modulus (YM), flexural modulus and fracture toughness (K _Ic) were found to decrease and impact energy (IE) was found to increase for both AUL and AAL composites. AUL composite had greater overall reduction in mechanical properties than that for AAL composite upon exposure to accelerated weathering environment. FTIR, TGA and WAXRD analyses of the accelerated weathered composites support the results of the deterioration of mechanical properties upon exposure to accelerated weathering environment.     

无溶剂环氧饮水舱涂料的制备

介绍了无溶剂环氧饮水舱涂料的配制,配方设计及技术性能指标,表明该涂料涂膜坚韧、密封性强,具有优良的耐水、防腐功能,无异味、异色和异常,堪称船舶的饮水舱、压载水舱、各种淡水柜及食品贮存室内壁等的一代新型高性能环保涂料。     

IPDI改性紫外光固化环氧丙烯酸酯涂料的研究

通过异佛尔酮二异氰酸酯(IPDI)改性环氧丙烯酸酯(四氢邻苯二甲酸二缩水甘油丙烯酸酯),以此改性预聚物配合活性稀释剂、光引发剂制得紫外光固化涂料。考察了不同—NCO与—OH配比对产物黏度的影响。通过FT-IR对预聚物的结构进行表征,用TGA研究固化膜的热性能,拉伸实验研究固化膜的力学性能。结果表明,反应物中当—NCO与—OH的物质的量比小于1时,—NCO与—OH比值越高则产物的黏度越大;改性后的光固化薄膜的拉伸强度能达到23 MPa以上,断裂伸长率比未改性以前提高了3倍以上,开始热分解的温度为150℃。     

改性环氧防腐涂料的研究进展

综述了近年来环氧防腐涂料改性的方法和进展,简述了这些改性方法对环氧防腐涂料性能的影响,最后对环氧防腐涂料的发展趋势进行了展望。     

浅色水性环氧导静电防腐涂料的研制

研制的水性环氧导静电防腐涂料为双组分涂料,甲组分由水性胺加成物固化剂、导电填料、防锈颜填料及助剂组成;乙组分由环氧树脂E51或OER-95、活性稀释剂、掺杂聚苯胺及偶联剂组成,按环氧/胺当量比为1.1∶1配漆,涂层具有优异的导静电性和防腐蚀性能。     

溶胶-凝胶/环氧杂化涂料的应用

溶胶-凝胶/环氧杂化涂料的配方已经进行了研究,杂化涂料具有更强的机械强度(如硬度),更加耐磨蚀。当固化温度提高到80℃,全部研究的杂化涂料都能通过湿性黏结试验,但在室温下固化时仅有部分的杂化涂料通过湿性黏结试验。多数杂化涂料在室温下固化时对水的敏感性问题尚待解决。     

长效无溶剂纯环氧压载舱防腐涂料

介绍了对环境友好的长效无溶剂纯环氧压载舱防腐涂料的研制过程及其优良的技术性能,它可广泛地用于压载舱内壁的防护装饰.     

紫外光固化环氧树脂涂层性质的研究

以双酚A型环氧树脂紫外光阳离子固化体系为对象，系统研究了光引发剂和各种单体组成对光固化速度及固化膜机械物理性质的影响。结果表明，光引发剂的种类不但可以有效地影响光固化速度，还能对涂层硬度产生影响；环氧稀释剂在降低体系黏度的同时，对光固化速度和硬度产生负面影响；而羟基化合物对光固化速度几乎不产生影响，但是可以大幅度提高涂层的硬度和柔韧性；三元体系中，由于存在加合作用，在光固化速度和物理机械性质两方面都得到了很好的结果。这就使得能够根据具体要求，配制出各种性能都较好的材料，将大大扩展阳离子紫外光固化技术的应用领域。     

环氧玻璃鳞片长效防腐涂料的制备

研制了一种环氧玻璃鳞片长效防腐涂料,玻璃鳞片经复合硅烷处理剂处理后,其用量在20％～30％时,涂层的防护效果最佳。盐雾试验4000h,湿热试验3000h,涂层无变化,具有优异的防腐性能,可用于海洋平台、石油化工等重防腐领域。     

高固体分环氧船舶压载舱涂料的制备

介绍了一种高固体分船舶压载舱涂料的制备方法。该涂料的特点是安全环保、高固体分、低温速干,涂层预期寿命15a,单道涂层干膜厚度160μm,名义干膜厚度320μm,涂层类型为浅色硬涂层,符合PSPC要求,适用于船舶压载舱内表面的涂层防护。