Toughening of vinyl ester resin using butadiene-acrylonitrile rubber modifiers

A common method for toughening thermoset resins is the addition of butadiene-acrylonitrile based rubber modifiers. A difficulty experienced by diglycidyl ether of bisphenol-A (DGEBA) vinyl esters (VE) compared to other thermosets is the solubility of the butadiene-acrylonitrile modifier. In this study, a miscible system was prepared by reducing the VE monomer molecular weight to 540 g/mol from industrially used monomers possessing molecular weights greater than 700 g/mol. A main objective of this study was to toughen the vinyl ester while limiting plasticization by varying rubber reactivity and concentration. All modified samples experienced a significant increase in fracture toughness with some degree of plasticization, as shown by losses in modulus and glass transition temperature (T_g). Epoxy terminated rubber (ETBN) yielded a higher toughness than vinyl terminated rubber (VTBN) due to the difference in rubber particle formation and resulting morphology. Chemical linkage of VTBN to the vinyl ester matrix hindered complete phase separation, but helped the retention of mechanical properties when compared to ETBN.     

溴化环氧乙烯基酯树脂的性能与应用

本文合成了一种溴化环氧乙烯基酯树脂,并对其力学性能、阻燃性、耐腐蚀性进行了表征.     

Incorporation of eicosapentaenoic and docosahexaenoic acids into groundnut oil by lipase-catalyzed ester interchange

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were incorporated into groundnut oil by interesterification with a 1,3-specific lipase fromMucor miehei. The resultant EPA and DHA concentrations of the groundnut oil were 9.5 and 8.0%, respectively.     

Preparation and characterization of poly(silyl ester)s containing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones

The two poly(silyl ester)s containing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones have been prepared via polycondensation reaction of di‐tert‐butyl adipate and di‐tert‐butyl fumarate with 2,2‐bis(p‐chloro dimethylsiloxy‐phenyl)propane to give tert‐butyl chloride as the condensate. The polymerizations were performed under nitrogen at 110°C for 24 h without addition of solvents and catalysts to obtain the poly(silyl ester)s with weight average molecular weights typically ranging from 5000 to 10,000 g/mol. Characterization of the poly(silyl ester)s included ¹H NMR and ¹³C NMR spectroscopies, infrared spectroscopy, ultraviolet spectroscopy, differential scanning calorimetry, thermogravimetric analysis (TGA), gel permeation chromatography, and Ubbelohde viscometer. The glass transition temperatures (T_g) of the obtained polymers were above zero because of the introducing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones. The TGA/DTG results showed that the obtained poly(silyl ester)s were stable up to 180°C and the residual weight percent at 800°C were 18 and 9%, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1937–1942, 2006     

One-step methodology for the synthesis of FA picolinyl esters from intact lipids

Picolinyl derivatives are used for structural determination of FA by GC-MS. Although they provide reliable diagnostic fragments, the usual multistep methodologies applied for their preparation require TAG hydrolysis or acid chloride formation prior to picolinyl synthesis. These reaction conditions may result in the presence of artifact molecules in the samples and thus compromise analytical quality and accuracy. To address these problems, a rapid, simple and quantitative methodology for the synthesis of FA picolinyl esters from intact lipids was developed. It involves their transesterification under basecatalyzed conditions using 3-potassiooxamethylpyridine in methylene chloride. The catalyst was prepared by proton exchange between potassium tert-butoxide and anhydrous 3-hydroxymethylpyridine. Mild reaction conditions allowed complete derivatization of TAG and phospholipids in 2 min at room temperature, and of FAME in 15 min at 45°C. The proposed procedure, which can be used on a routine basis, was applied to Ipomoae imperialis seed lipids and used to confirm occurrence of γ-linoleic acid at a level of 0.9%.     

Synthesis of novel photo-cross-linkable polymers with redissolution property

p-Styrenesulfonate derivatives having cycloaliphatic epoxide in a molecule, were synthesized. Oligomerization of the monomers and co-polymerization of the novel monomers with tert-butyl methacrylate were carried out. When the polymer films containing a photoacid generator (PAG) were irradiated, they became insoluble in solvents. The insoluble films became soluble in water on baking at 120-200 °C. The insolubilization and redissolution profiles were strongly affected by the structure of the monomer, irradiation and baking conditions, and a type of PAG used. The reaction mechanism was studied by TGA analysis and FT-IR spectroscopy.     

Hydrodeoxygenation of methyl esters on sulphided NiMo/γ-Al2O3 and CoMo/γ-Al2O3 catalysts

Wood-derived bio-oil contains high amounts of compounds with different oxygen-containing functional groups that must be removed to improve the fuel characteristics. Elimination of oxygen from carboxylic groups was studied with model compounds, methyl heptanoate and methyl hexanoate, on sulphided NiMo/γ-Al₂O₃ and CoMo/γ-Al₂O₃ catalysts in a flow reactor. Catalyst performances and reaction schemes were addressed. Aliphatic methyl esters produced hydrocarbons via three main paths: The first path gave alcohols followed by dehydration to hydrocarbons. Deesterification yielded an alcohol and a carboxylic acid in the second path. Carboxylic acid was further converted to hydrocarbons either directly or with an alcohol intermediate. Decarboxylation of the esters led to hydrocarbons in the third path. No oxygen-containing compounds were detected at complete conversions. However, the product distributions changed with time, even at complete conversions, indicating that both catalysts deactivated under the studied conditions.     

环氧乙烯基酯树脂及层合板的耐碱性能

对双酚A型环氧乙烯基酯树脂及应用于各种纤维增强层合板的耐碱性进行了分析,认为:要提高纤维增强复合材料的耐碱性,需选择耐碱性较好并能与纤维良好浸润的乙烯基树脂,选择锦纶等耐碱性较好的有机纤维。     

青霉素生产废液处理工艺改进

对青霉素废液中醋酸丁酯回收过程中酯含量偏低的问题进行了研究,提出了解决办法,通过生产验证证明改进后的工艺可以有效地提高回收醋酸丁酯的酯含量。     

含氮硼酸酯与磷酸酯添加剂在PAO10中的摩擦特性协同效应

合成一种含氮硼酸酯润滑油添加剂二羟乙基十八胺硼酸酯,利用四球摩擦磨损试验机考察其分别和磷酸三丁酯、磷酸三甲酚酯复配后在基础油PAO10中的摩擦学性能;采用扫描电子显微镜对磨损表面形貌进行分析。结果表明:合成的含氮硼酸酯与磷酸酯复配后表现出比其单剂更优异的抗磨减摩性能,两者在摩擦学性能上具有很好的协同效应;极压性能随着磷元素含量的减少而变差;含氮硼酸酯与磷酸酯复配后可使摩擦副表面磨痕变浅,磨斑减小。