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41.
柔软热收缩材料的研制 总被引:2,自引:0,他引:2
总结了经共混和辐射交联制备柔软耐老化的热收缩材料的研制过程。测得了不同乙丙橡胶含量和不同辐照剂量下的共混物的力学性能和凝胶含量,确定了共混物辐射交联的合适剂量。此外,还测试了EPDM和PE共混物经辐照后的耐油性能。在此基础上,制得了手感柔软的热收缩管材。 相似文献
42.
介绍了我国乙二醇市场现状,截至2019年底,我国乙二醇总产能为1 159万吨/年,其中,煤制乙二醇产能达491万吨/年,2020年还将有近400万吨/年的产能释放。煤制乙二醇技术逐渐成熟,所以短期内市场存在产能增速较快但产量增速缓慢的不匹配状态。比较了石油制乙二醇和煤制乙二醇生产工艺路线的成本,从生产成本、产品质量和物流方式3个维度分析了煤制乙二醇的市场竞争力,得出了煤制乙二醇的发展具有广阔前景,并根据国内乙二醇市场的远期发展趋势,提出了发展建议。 相似文献
43.
Reactor blends of polyethylene/poly(ethylene-co-1-octene) resins with bimodal molecular weight and bimodal short chain branching distributions were synthesized in a two-step polymerization process. The compositions of these blends range from low molecular weight (LMW) homopolymer to high molecular weight (HMW) copolymer and, vice versa, HMW homopolymer to LMW copolymer. The physical properties of the blends were found to be consistent with the nature of the individual components. For the tensile properties, the stiffness decreases with increasing the fraction of the copolymer, regardless of the molecular weight of the homopolymer fraction. For these blends with bimodal microstructures, it was confirmed that the degree of crystallinity governs the stiffness of the polymer. However, the energy dampening properties of the polymers benefit from the presence of the copolymer. A balance of stiffness and toughness can be obtained by altering the composition of the blends. For some blends, the presence of HMW homopolymer can dominate the tensile properties, showing little variation in the stiffness with increased addition of copolymer. It was also demonstrated that the testing conditions and thermal treatment of the polymer greatly influence the resulting elastic and energy dampening properties. Depending on the desired application, annealing these polymers (especially very low density copolymers) not only increases the crystallinity and stiffness, but also changes the frequency response of the dynamic mechanical properties. 相似文献
44.
新显色剂4—(2—苯并噻唑偶氮)邻苯二酚—钼(Ⅵ)—OP体系的分光光度研究 总被引:2,自引:1,他引:2
在pH5.0~5.7范围内,新显色剂4-(2-苯并噻唑偶氮)邻苯二酚(BTAPC)与钼(Ⅵ)和非离子表面活性剂OP反应,形成稳定的、带负电荷的、紫红色三元胶束配合物。该配合物中Mo(Ⅵ)与BTAPC的组成比为1∶2;其λmax为560nm,对比度(Δλ)为128nm;在20℃、pH5.2和μ0.1时,配合物的表观稳定常数为3.02×1010,表观摩尔吸光系数ε560为8.11×104L·mol-1·cm-1,真实ε560为7.67×104L·mol-1·cm-1。钼含量在0~0.72mg/L范围内遵从比耳定律。建议了配合物的结构。本法简便、快速、准确,用于合金钢试样中痕量或小量钼的测定,取得了满意的结果。 相似文献
45.
自行研制了氰乙基(25%,质量分数)甲基硅橡胶(XE-60)石英毛细管色谱柱。建立了对含游离酸的丙二醇单甲醚丙酸酯的色谱分析方法。该法具有分离效果好,分析速度快的优点。 相似文献
46.
Poly(L‐lactide)‐poly(ethylene glycol) multiblock copolymers with predetermined block lengths were synthesized by polycondensation of PLA diols and PEG diacids. The reaction was carried out under mild conditions, using dicyclohexylcarbodiimide as the coupling agent and dimethylaminopyridine as the catalyst. The resulting copolymers were characterized by various analytical techniques, such as GPC, viscometry, 1H‐NMR, FTIR, DSC, X‐ray diffractometry, and contact angle measurement. The results indicated that these copolymers presented outstanding properties pertinent to biomedical use, including better miscibility between the two components, low crystallinity, and hydrophilicity. Moreover, the properties of the copolymers can be modulated by adjusting the block length of the two components or the reaction conditions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1729–1736, 2002; DOI 10.1002/app.10580 相似文献
47.
Analysis of the polyethylene glycol glucosides and FA esters thereof by atmospheric-pressure ionization MS 总被引:1,自引:0,他引:1
Xin?Jin Jinzong?YangEmail author Bingtao?Tang Minggui?Zhu Ning?Yu Yi?Liu 《Journal of the American Oil Chemists' Society》2003,80(6):519-524
Polyethylene glycol (PEG) glucosides (PEGG) and the PEGG esters of lauric acid were analyzed by atmospheric-pressure ionization
MS (API-MS) with electrospray ionization. Straightforward mass characterization of the complex mixtures could be achieved
without prior chromatographic separation. The constituents were identified on the basis of quasi-molecular ions. Individual
components could be observed as protonated molecular ions [M+H]+ and/or as their NH4
+, Na+, or K+ adducts in positive ion mode. The mass spectrometric investigation showed that mixtures of PEGG consisted of monoglucoside,
diglucoside, polyglucoside, and free PEG. The esterification product is a mixture of two types of nonionic surfactants: PEG-laurates
and PEGG-laurates. The reasons for distortion of the quasi-molecular ion intensities and the stabilization of adduct ions
were discussed. The rapid and highly sensitive API-MS analysis technique proposed here is well suited for direct characterization
of complex mixtures and suitable for development as a routine analytical method. 相似文献
48.
49.
Poly(ethylene terephthalate) films were treated with aqueous sodium hydroxide solutions of different concentrations for various times. The rate of weight loss increased with the addition of a swelling agent (methylene chloride) or a cationic surfactant. The surface roughness of the treated films was determined from atomic force microscopy (AFM) and pore diameter was obtained from scanning electron microscopy (SEM). In general, surface roughness was found to increase with increasing weight loss for the treated films. A maximum roughness was obtained for samples with a weight loss of approximately 15-20%, beyond which the roughness of the samples decreased. The addition of methylene chloride and surfactant resulted in an almost two-fold increase in the roughness for all treatment times investigated. The adhesion of electrolessly plated platinum film was dependent on the contact area produced by chemical treatment. Treatments producing smaller diameter pores of greater depth gave better adhesion. 相似文献
50.
Hydrogenolysis of biomass-derived glycerol is an alternative route to sustainable production of propylene glycol. Cu–ZnO catalysts
were prepared by coprecipitation with a range of Cu/Zn atomic ratio (0.6–2.0) and examined in glycerol hydrogenolysis to propylene
glycol at 453–513 K and 4.2 MPa H2. These catalysts possess acid and hydrogenation sites required for bifunctional glycerol reaction pathways, most likely involving
glycerol dehydration to acetol and glycidol intermediates on acidic ZnO surfaces, and their subsequent hydrogenation on Cu
surfaces. Glycerol hydrogenolysis conversions and selectivities depend on Cu and ZnO particle sizes. Smaller ZnO and Cu domains
led to higher conversions and propylene glycol selectivities, respectively. A high propylene glycol selectivity (83.6%), with
a 94.3% combined selectivity to propylene glycol and ethylene glycol (also a valuable product) was achieved at 22.5% glycerol
conversion at 473 K on Cu–ZnO (Cu/Zn = 1.0) with relatively small Cu particles. Reaction temperature effects showed that optimal
temperatures (e.g. 493 K) are required for high propylene glycol selectivities, probably as a result of optimized adsorption
and transformation of the reaction intermediates on the catalyst surfaces. These preliminary results provide guidance for
the synthesis of more efficient Cu–ZnO catalysts and for the optimization of reaction parameters for selective glycerol hydrogenolysis
to produce propylene glycol. 相似文献