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921.
922.
923.
Mohammad A. Rahman Biing-Ming Su Elliot Band Mojahedul Islam 《Journal of surfactants and detergents》2011,14(3):333-338
An efficient procedure for the regioselective synthesis of secondary alcohol alkoxylates from 2,2,4-trimethyl-1,3-pentanediol (TMPD) is described. TMPD was reacted with propylene oxide followed by ethylene oxide in the presence of a catalytic amount of alkali metal hydroxide to form secondary alcohol alkoxylates. Instead of a mixture of compounds resulting from the reaction of TMPD and propylene oxide, the primary hydroxyl group of the TMPD reacted to form predominantly 2,2,4-trimethyl-3-hydroxypentylpropoxylate as the major product. On further ethoxylation the less hindered secondary hydroxyl group of the 2,2,4-trimethyl-3-hydroxypentylpropoxylate reacted predominantly. 13C NMR indicated that the secondary hydroxyl group (96.2 mol%) of TMPD remained unreacted during alkoxylation. 相似文献
924.
黄原胶/膨润土复合高吸水性树脂的制备与性能研究 总被引:1,自引:0,他引:1
采用水溶液聚合法制备了黄原胶(XG)/膨润土有机-无机复合SAP(高吸水性树脂)。通过单因素试验法和正交试验法优选出制备复合SAP的最佳工艺条件。结果表明:丙烯酸(AA)、丙烯酰胺(AM)、XG与膨润土之间发生了接枝共聚反应;当m(AA)∶m(AM)=5∶1、AA中和度为75%、w(膨润土)=5%、w(引发剂)=1.0%和w(交联剂)=0.08%时,相应的复合SAP具有最大的吸水倍率(863.8 g/g)和吸盐水倍率(109.4 g/g)。 相似文献
925.
926.
文章采用臭氧/活性炭组合工艺对甲基红印染废水进行降解试验,考察了甲基红废水的pH、活性炭投加量、温度和臭氧流量等参数对印染废水色度和CODCr去除率的影响,确定了臭氧/活性炭组合工艺降解甲基红印染废水的最佳工艺条件。结果表明,在pH为3.5,温度为25℃,活性炭投加量为120 mg/L,臭氧流量为0.83 L/min,初始浓度为10 mg/L的条件下降解10 min,臭氧/活性炭组合工艺对甲基红废水的脱色率达到97.4%,CODCr去除率达到85.2%。该组合工艺能有效地去除印染废水的色度和CODCr,使出水水质达到处理标准。 相似文献
927.
928.
Wen-Fen Su 《Polymer》2011,52(1):77-4752
This paper describes the synthesis of a new thermally cross-linkable hole-transporting poly(fluorene-co-triphenylamine) (PFTV) by Suzuki coupling reaction and its application in polymer light-emitting diodes (PLEDs). The characteristics of PFTV were analyzed by 1H NMR, differential scanning calorimetry, optical spectroscopy, cyclic voltammetry, and atomic force microscopy. Its HOMO level lies between those of PEDOT:PSS and poly(9,9-dioctylfluorene), forming a stepwise energy ladder to facilitate hole-injection. Multilayer device with thermally cross-linked PFTV as hole-transporting layer (ITO/PEDOT:PSS/HTL/PFO/LiF/Ca/Al) was readily fabricated by successive spin-coating processes, its maximum luminance efficiency (2.27 cd/A) was significantly higher than that without PFTV layer (0.50 cd/A). In addition, the PFTV was successfully applied as host for red-emitting Ir(piq)2acac to obtain a device with moderate performance (5300 cd/m2 and 2.64 cd/A). The PFTV is a promising hole-transporting material for the fabrication of multilayer PLEDs by wet processes as well as a potential host for phosphorescent PLEDs. 相似文献
929.
With an atomic-force microscope and a grazing-incidence small-angle X-ray scattering we studied ex situ the evolution of hierarchical structures in isothermally annealed ultrathin films of asymmetric polystyrene-block-poly(methyl methacrylate) P(S-b-MMA) that dewetted on polar substrates via a mechanism involving nucleation and growth. Film instability causes the surface to acquire an undulating thickness through incommensurability, producing not only the relief structures on a micrometer scale but also mesophase-separated domains on a nanometer scale. The dewetted morphologies strongly influence the ordering behavior of the nanoscale domains. The noncylindrical nanostructures become stable at the curved edges of the relief microstructures in the destabilized P(S-b-MMA) films, for which a preferential wetting of the PS block with the free surface is prohibited. Additionally, the shape of relief structures as result of film instability correlates with the formation of mesophase-separated nanodomains. At early stages of film instability, the formation of parallel-oriented PMMA cylindrical nanodomains increases the deformation energy and it further persists to force the shape of relief structures between irregular holes to have a facet-wedge shape. However, those relief structures are expected to be not at equilibrium. At high temperatures, the relief structures between irregular holes progressively developed to form hemispherical-cap drops accompanied by a transformation of cylindrical into noncylindrical nanodomains at curved surfaces. 相似文献
930.
The effects of injection and ignition timings, engine speed and load, compression ratio and injector configuration on cycle-by-cycle combustion variation in a direct-injection spark ignition (DISI) engine fueled with methanol have been studied experimentally. The coefficient of variation (COV) of the maximum in-cylinder pressure was used to evaluate the cycle-by-cycle combustion variation. The results showed that these factors significantly affect the cycle-by-cycle combustion variation. The COV reaches the least at an optimal injection and ignition timings. The COV at a compression ratio of 14:1 is less than that at a compression ratio of 16:1 at light load, and vice versa at high load. The COV using injector type A is significantly less than that when using types B and C. 相似文献