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1.
Novel diols containing imide groups were prepared via condensation of aromatic dianhydrides with 5‐amino‐1‐naphthol. The diimide–dinaphthols prepared were characterized by conventional methods and used to synthesize new poly(urethane–imide)s (PUIs). All the polymers were characterized and their physical properties, such as solubility, solution viscosity, thermal stability, and thermal behaviour were studied. The polymers obtained showed more thermal stability than typical polyurethanes because of the presence of the imide groups. Copyright © 2003 Society of Chemical Industry 相似文献
2.
The synthesis of monodisperse hard segments containg 2,4-TDI and 1,4-butanediol by a simple technique is described. High purity material is obtained in good yield. The structures of these hard segments are confirmed by proton n.m.r., 13Cn.m.r., and i.r. Glass transition temperatures and melting temperatures are reported. The Tg′s of the hard segments are inversely proportional to the reciprocal of their molecular weights. The Tm′s show an odd-even effect relative to the number of 2,4-TDI units in the hard segment. 相似文献
3.
研究了在GB/T18446-2001方法基础上改变内标物(使用无毒性记录的十二烷代替毒性大的1,2,4-三氯代苯)测定样品中游离TDI的方法。该方法简捷、快速、准确度高、精确度高、更环保。本方法的适用范围同GB/T18446-2001。 相似文献
4.
研究了二氧化碳与己二胺甲氧羰基化反应合成六亚甲基二异氰酸酯,考察了有机碱用量、反应温度、反应时间和压力等操作条件对反应的影响。结果表明最佳工艺条件:n(三乙胺):n(己二胺)=3:1,反应温度-5℃、反应时间60min、压力为0.55MPa。并用红外谱图和折光率对合成产物进行表征。 相似文献
5.
The use of isopropanol (IPA) as the reaction solvent for the preparation of high molecular weight segmented polyether-urea copolymers based on cycloaliphatic diisocyanates was investigated. Reactivity of IPA with bis(4-isocyanatohexyl)methane (HMDI) and isophorone diisocyanate (IPDI) was studied between 0 and 40 °C using in-situ FTIR spectroscopy. HMDI, which has secondary isocyanate groups, shows a very slow reaction with a large excess of IPA at 0 and 23 °C. Analysis of the kinetic data indicates an activation energy of 51 kJ/mol for the reaction between HMDI and IPA. As expected, IPDI, which has both a primary and a secondary isocyanate (NCO) group, reacts faster with IPA compared with HMDI, which only has secondary NCO groups. However, the rate of reaction of IPDI with IPA at 0 °C is extremely slow (approximately 1% consumption of isocyanate in 60 min) thus allowing the use of IPA as the reaction solvent for polyether-urea synthesis. Preparation of high molecular weight, high-strength HMDI and IPDI based polyether-urea segmented copolymers in IPA has been demonstrated. Thermal analysis and stress-strain analyses were used to characterize the products. 相似文献
6.
Butan‐1‐ol modified toluene diisocyanate tri mer (TDI‐trimer) was synthesized and characterized with Fourier transform infrared spectroscopy, gel permeation chromatography, and thermal gravimetry analysis techniques. The modified TDI‐trimer showed good dissolvable ability with hydroxy resin and can be used to produce paints with acrylic polyol resin. The thermal stability of the modified TDI‐trimer was improved by simply increasing both the amount of catalyst and the ratio of ? NCO/? OH, less depended on the kind of catalyst. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4958–4962, 2006 相似文献
7.
Polyester polyurethane cationomers are prepared using polyester polyol of molecular weight 2000 as soft segments, N-methyl diethanolamine as chain extender, glycolic acid as quaternization agent, methyl ethyl ketone as solvent, and 4,4'-diphenylenemethylene diisocyanate (MDI) as diisocyanate. Properties of the films cast from solutions and emulsions are studied by infrared spectroscopy, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, and tensile-elongation testing. Ionization can cause phase separation and produces increased cohesion in the hard domains. The dispersion process can be divided into three stages involving a separation of hard segment aggregates due to adsorption of water on their surface, water entering into hard segment microionic lattics, and finally a rearrangement of agglomerates to form microspheres. The dispersion can disrupt the order in the hard domains and an increased phase separation. 相似文献
8.
Polyurethane prepolymers prepared from toluene 2,4‐diisocyanate, toluene 2,6‐diisocyanate, and polypropylene glycol with a ratio between the isocyanate and hydroxyl groups equal to 2 were analyzed by 1H nuclear magnetic resonance (NMR) spectroscopy in acetone‐d6. Different temperatures and concentrations were used. Toluene 2,4‐dimethylurethane and toluene 2,6‐dimethylurethane were synthesized and used as model compounds to assign prepolymers signals. Measurements of spin–lattice relaxation time T1 by “inversion recovery” experiments were carried out on toluene 2,4‐diisocyanate, toluene 2,6‐diisocyanate, toluene 2,4‐dimethylurethane, toluene 2,6‐dimethylurethane, and polyurethane prepolymers. Differences in T1 times were used to interpret prepolymers spectra, by means of the strong observed effect on protons due to the presence of adjacent isocyanate groups. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 347–357, 2003 相似文献
9.
以4,4′-二苯基甲烷二异氰酸酯(MDI)为反应增容剂,采用熔融共混法制备了不同MDI含量的聚乳酸/热塑性聚氨酯(PLA/TPU)共混物,采用傅里叶变换红外光谱仪(FTIR)、万能试验机、冲击试验机、扫描电子显微镜(SEM)、差示扫描量热仪(DSC)和旋转流变仪对共混物力学性能、微观形态、热性能和流变性能进行了研究。结果表明:MDI可以有效改善共混物的力学性能,当MDI质量分数为1%时,共混物力学性能最佳,缺口冲击强度为40.0kJ/m2,断裂伸长率为214.1%,与未加MDI的共混物相比,分别增加了4.3倍和5.8倍,拉伸强度稍有下降(47.6MPa);SEM表明,MDI的加入提高了共混物的相容性,加入MDI后,共混物的断面由海-岛结构变为核-壳包覆结构,相界面作用力增强;DSC测试表明,共混物的玻璃化转变温度、冷结晶温度和熔融温度随着MDI含量的增加而升高;流变测试表明,MDI质量分数的增加,共混物呈现更显著的剪切变稀行为,推测共混反应机理为:MDI质量分数的增加,体系内依次发生PLA的扩链、支化和TPU的交联。 相似文献
10.
为改善高固含量高聚物黏结炸药(PBX)和丁羟推进剂的工艺性能,以低分子量的端羟基聚丁二烯(HTPB)、异佛尔酮二异氰酸酯(IPDI)为主要原料,选用一缩二乙二醇(DEG)为扩链剂,采用二步法制备了聚氨酯弹性体。研究了催化剂用量对浆料黏度的影响,固化参数R及扩链剂用量对HTPB聚氨酯弹性体力学性能的影响。试验结果表明,当催化剂质量分数为0.004%时,适用期可达5 h;R值为1.1,DEG羟基含量占反应总羟基量的60%时,聚氨酯弹性体力学性能较好,拉伸强度达7.60 MPa,断裂伸长率达540.21%。动态力学分析(DMA)测试结果显示,低分子量HTPB聚氨酯弹性体有两个明显的玻璃化转变温度,说明样品存在明显的微相分离结构。 相似文献