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31.
Roser Cervellera Xavier Ramis Josep Maria Salla Ana Mantecn Angels Serra 《Journal of polymer science. Part A, Polymer chemistry》2006,44(9):2873-2882
N,N‐Dimethylaminopyridine (DMAP) was used as initiator to cure mixtures of diglycidylether of bisphenol A (DGEBA) and 1,3‐dioxan‐2‐one (TMC) or 5,5‐dimethyl‐1,3‐dioxan‐2‐one (DMTMC). The curing was studied by differential scanning calorimetry (DSC) and Fourier transform infrared in the attenuated‐total‐reflection mode (FTIR/ATR). FTIR/ATR was used to monitor the competitive reactive processes and to quantify the evolution of the groups involved in the curing. We observed the formation of five‐membered cyclic carbonates and anionic carbonate groups that remain unreacted at the chain ends. The formation of these groups was explained by the attack of the anionic propagation species on the methylene carbon of the carbonate group, which leads to an alkyl‐oxygen rupture. By performing the cure in the thermobalance we could evaluate the loss of CO2 produced in the samples containing carbonates. The kinetics were studied by DSC and analyzed with isoconversional procedures. The addition of carbonates slows down the curing rate. Thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) experiments were used to evaluate the properties of the materials obtained. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2873–2882, 2006 相似文献
32.
We have carried out some photon interaction measurements using 59.54 keV γ-rays from a 241Am source. These include γ attenuation studies as well as photoelectric absorption studies in various samples. The attenuation
studies have been made using leaf and wood samples, samples like sand, sugar etc., which contain particles of varying sizes
as well as pellets and aqueous solutions of rare earth compounds. In the case of the leaf and wood samples, we have used the
γ-ray attenuation technique for the determination of the water content in fresh and dried samples. The variation of the attenuation
coefficient with particle size has been investigated for sand and sugar samples. The attenuation studies as well as the photoelectric
studies in the case of rare earth elements have been carried out on samples containing such elements whose K-absorption edge
energies lie below and close to the γ-energy used. Suitable compounds of the rare earth elements have been chosen as mixture
absorbers in these investigations. A narrow beam good geometry set-up was used for the attenuation measurements. A well-shielded
scattering geometry was used for the photoelectric measurements. The mixture rule was invoked to extract the values of the
mass attenuation coefficients for the elements from those of the corresponding compounds. The results are consistent with
theoretical values derived from the XCOM package. 相似文献
33.
ZnCuCoAlNO3型四元水滑石及其多氧阴离子柱撑物的合成与催化氧化性能 总被引:4,自引:0,他引:4
Anionic clay, ZnCuCoAlNO3 and its polyoxometalate intercalates were synthesized, and were characterized by XRD, IR, 31PMAS NMR, DTA and elemental analysis. The pillared products are found to be effective catalysts for oxidation of cyclohexene with molecular oxygen under mild reaction conditions 相似文献
34.
α—甲基苯乙烯离子聚合体分子量分布 总被引:1,自引:0,他引:1
聚α-甲基苯乙烯-丁二烯-α-甲基苯乙烯嵌段共聚物是一种性能优异的热塑性弹性体。常温下,α-甲基苯乙烯的聚合是在极性添加剂存在下进行的,添加剂的种类,用量及聚合温度不仅影响聚合动力学,尚且影响聚合物分子量及其分布,控制α-甲基苯乙烯聚合速率、 相似文献
35.
表面活性剂增敏阴极溶出伏安法测定痕量的碘 总被引:4,自引:0,他引:4
本介绍在KNO3-VC-EDTA-Triton X-100混合底液中,用悬汞电极2.5次微分阴极溶出伏安法测定痕量碘的方法及其最佳条件。引入表面活性剂Triton X-100可显提高灵敏度,I^-的检测下限达0.1ng·mL^-1(电积180s);引入VC可提高I^-的稳定性(抗氧化性);EDTA和VC有效率地提高了方法的抗干扰能力。用于饮水中痕量碘的分析,其相对标准偏差为3.3%(n=7), 相似文献
36.
聚电解质与相反电荷表面活性剂的相互作用 总被引:2,自引:0,他引:2
通过透光度测定、电导滴定和粘度法考察了阳离子聚电解质聚苯乙烯 4 乙烯基吡啶硫酸甲酯盐与阴离子表面活性剂十二烷基硫酸钠 (SDS)的相互作用。研究表明 ,在表面活性剂未过量时 ,二者之间的静电作用占主导地位 ,并且当二者电荷总量相等时 ,生成的复合物沉淀最多 ;在表面活性剂过量后 ,复合物可部分溶解 ,溶解的原因是疏水相互作用。本文初步阐述了二者的作用机理 相似文献
37.
An emulsion polymerization of styrene in the presence of an amphoteric surfactant; N,N-dimethyl-n-laurylbetaine (LNB) was carried out at pH 7.0. The polymerization rate and the concentration of the latex particle were proportional to the LNB concentration of 0.6 power. The latex particle sizes became smaller with increasing concentrations of LNB. The molecular weights of polystyrene latices increased with the concentration of LNB. The zeta-potentials of latex particles were significantly dependent on the pH, and showed the existence of an isoelectric point. 相似文献
38.
The micellization behavior of an anionic gemini surfactant, GA with nonionic surfactants C12E8 and C12E5 in presence of 0.1 M NaCl at 298 K temperature, has been studied tensiometrically in pure and mixed states, and the related
physicochemical parameters (cmc, γ
cmc, pC
20, Γ
max, and A
min) have been evaluated. Tensiometric profile (γ vs log [surfactant]), for conventional surfactants, generally consists of a single point of intersection; a gradually decreasing
line (normally linear, or with slight curvature) ultimately saturates in γ at a particular [surfactant], corresponding to complete monolayer saturation. The gemini, in this report, led to two unequivocal
breaks in the tensiometric isotherm. An attempt to the interpretation of the two breaks from molecular point of view is provided,
depending solely on the chemical structure of the surfactant. The gemini, even in mixed state with the conventional nonionic
surfactants C12E5 and C12E8, manifested the dual breaks; of course, the dominance of the feature decreases with increasing mole fraction of the nonionics
in the mixture. Theories of Clint, Rosen, Rubingh, Motomura, Georgiev, Maeda, and Nagarajan have been used to determine the
interaction between surfactants at the interface and micellar state of aggregation, the composition of the aggregates, the
theoretical cmc in pure and mixed states, and the structural parameters according to Tanford and Israelachvili. Several thermodynamic
parameters have also been predicted from those theories. 相似文献
39.
YiJianCHEN GuiYingXU ShiLingYUAN HaiYingSUN 《中国化学快报》2005,16(5):688-690
Molecular dynamics (MD) simulation are used to study the properties of gemini surfactant of ethyl-α,ω-bis(dodecyldimethylammonium bromide) (C12C2C12) and dodecyl-trimethylammonium bromide (DTAB) at the air/water interface, respectively. In the two systems,t he surfactant concentrations are both 28 wt.%, and other conditions are also the same. After reaching the thermodynamic equilibrium, the concentration profiles, the radial distributions functions (RDF) and the mean squared displacement (MSD) are investigated. The results reveal that the surface activity of C12C2C12 surfactant is higher than DTAB surfactant. 相似文献
40.
Excess volumes V
E
of binary liquid mixtures of quinoline with alkanols have been determined from densities at 30°C as a function of composition. The excess volumes are negative over the whole mole fraction range for all the mixtures and decrease with increasing length of alkanol (C1–C10). The VE data have been analyzed in terms of an approach which uses graph theoretical connectivity parameters of the third degrees for two components. The analysis gives information regarding associated species in the pure state and in the mixture. It is suggested that, in the mixture state, no change occurs in the association of alkanols. 相似文献