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91.
John L. Gardon 《Progress in Organic Coatings》1997,32(1-4):73
Aqueous binder resins are becoming increasingly diversified and encompass classical latexes, latex-like polyurethane dispersions, and various aqueous dispersion polymers. Unlike classical and urethane latexes, the dispersion polymers are synthesized in non-aqueous media, have low molecular weights and are dispersed into water by mechanical means. The preparation of classical latexes from unsaturated monomers is scientifically well understood. Modem classical latex technology provides precise particle size control and the means to impart core-shell morphology to the particles. Core-shell morphology is beneficial for improved film formation, rheology and crosslink acceptance. Polyurethane dispersions are made by extending the molecular weight of isocyanate-terminated prepolymers with aqueous diamines. Though more expensive, polyurethane dispersion binders complement classical latexes by yielding tougher and generally more solvent resistant films. The low molecular weight acrylic, alkyd, polyester and epoxy dispersion polymers have advantages in good atomization, high gloss and flow-out in film formation Current progress includes improved scientific understanding of urethane latexes and of dispersion polymers. This is paralleled by the development of novel crosslinking systems. 相似文献
92.
尿素和甲醛合成脲醛树脂粘合剂的动力学研究 总被引:9,自引:3,他引:9
本文讨论了尿素和甲醛反应生成际醛树脂粘合剂的反应机理及其可能的控制步聚,提出了反应速度方程模型。通过实验测定了在不同的温度、反应物料初始条件下的甲醛反应速率,得到了反应的动力学参数。结果表明该反应为二级不可逆反应。 相似文献
93.
脲醛树脂乳液干燥成粉末的试验研究 总被引:2,自引:0,他引:2
进行了用惰性粒子流化床干燥器将脲醛树脂乳液干燥成粉末的试验研究,产出了品质好的干粉,得出了在试验条件下的干燥强度和热效率,并作了经济性评价。 相似文献
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合成了三聚氰胺-尿素-甲醛(MUF)共缩聚树脂,考察了不同施胶量、固化剂用量及木材种类对胶合木性能的影响。结果表明,MUF共缩聚树脂用量为300g/m2,双面施胶,固化剂用量在1~2%时,生产的胶合木性能最优。 相似文献
97.
Jihua Wang Jingfeng Lou Chao Luo Ligang Zhou Mingan Wang Lan Wang 《International journal of molecular sciences》2012,13(9):11349-11364
Halimodendron halodendron has been used as forage in northwestern China for a long time. Its young leaves and flowers are edible and favored by indigenous people. In this study, eleven phenolic compounds were bioassay-guided and isolated from the aerial parts of H. halodendron for the first time. They were identified by means of physicochemical and spectrometric analysis as quercetin (1), 3,5,7,8,4′-pentahydroxy-3′-methoxy flavone (2), 3-O-methylquercetin (3), 3,3′-di-O-methylquercetin (4), 3,3′-di-O-methylquercetin-7-O-β-d-glucopyranoside (5), isorhamentin-3-O-β-d-rutinoside (6), 8-O-methylretusin (7), 8-O-methylretusin-7-O-β-d-glucopyranoside (8), salicylic acid (9), p-hydroxybenzoic acid (ferulic acid) (10), and 4-hydroxy-3-methoxy cinnamic acid (11). They were sorted as flavonols (1–6), soflavones (7 and 8), and phenolic acids (9–11). Among the compounds, flanools 1–4 revealed a strong antibacterial activity with minimum inhibitory concentration (MIC) values of 50–150 μg/mL, and median inhibitory concentration (IC50) values of 26.8–125.1 μg/mL. The two isoflavones (7 and 8) showed moderate inhibitory activity on the test bacteria. Three phenolic acids (9, 10 and 11) showed strong antibacterial activity with IC50 values of 28.1–149.7 μg/mL. Antifungal activities of the compounds were similar to their antibacterial activities. All these phenolic compounds showed significant antimicrobial activity with a broad spectrum as well as antioxidant activity based on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and β-carotene-linoleic acid bleaching assays. In general, the flavonol aglycones with relatively low polarity exhibited stronger activities than the glycosides. The results suggest the potential of this plant as a source of functional food ingredients and provide support data for its utilization as forage as well. 相似文献
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采用多聚甲醛代替37%甲醛溶液与苯酚逐步加成聚合,合成可发性甲阶酚醛树脂。通过粘度、固含量、游离苯酚和甲醛含量及凝胶时间测定以及IR,GPC和TG分析研究了多聚甲醛-苯酚物质的量比为1.8∶1条件下,缩聚反应温度及催化剂加入量对可发性甲阶酚醛树脂性能的影响。结果表明,缩聚反应温度为90℃,催化剂质量分数为5%(以苯酚质量计)时,可得到性能优良的可发性甲阶酚醛树脂,其性能如下:粘度2.6 Pa·s,游离甲醛质量分数1.23%,游离苯酚质量分数5.13%,热失重质量残留率50%以上。 相似文献