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71.
72.
P.S. Vijayanand 《European Polymer Journal》2007,43(5):2046-2056
The novel methacrylic monomer, 4-nitro-3-methylphenyl methacrylate (NMPM) was synthesized by reacting 4-nitro-3-methylphenol dissolved in ethyl methyl ketone (EMK) with methacryloyl chloride in the presence of triethylamine as a catalyst. The homopolymer and copolymers of NMPM with glycidyl methacrylate having different compositions were synthesized by free radical polymerization in EMK solution at 70 ± 1 °C using benzoyl peroxide as free radical initiator. The homopolymer and the copolymers were characterized by FT-IR, 1H NMR and 13C NMR spectroscopic techniques. The solubility tests were tested in various polar and non-polar solvents. The molecular weight and polydispersity indices of the copolymers were determined using gel permeation chromatography. The glass transition temperature of the copolymers increases with increase in NMPM content. The thermogravimetric analysis of the polymers performed in air showed that the thermal stability of the copolymer increases with NMPM content. The copolymer composition was determined using 1H NMR spectra. The monomer reactivity ratios were determined by the application of conventional linearization methods such Fineman-Ross (r1 = 1.862, r2 = 0.881), Kelen-Tudos (r1 = 1.712, r2 = 0.893) and extended Kelen-Tudos methods (r1 = 1.889, r2 = 0.884). 相似文献
73.
Manuel Snchez-Chaves Gerardo Martínez Enrique Lpez Madruga 《Journal of polymer science. Part A, Polymer chemistry》1999,37(15):2941-2948
2-Hydroxyethyl methacrylate (HEMA) and styrene (S) have been copolymerized in a 3 mol · L−1N,N′-dimethylformamide (DMF) solution using 2,2′azobis (isobutyronitrile) (AIBN) as an initiator over a wide composition and conversion range. From low-conversion experiments and 1H-NMR analysis, the monomer reactivity ratios were determined according to the Mayo–Lewis terminal model. The comparison of the obtained results with those previously reported for copolymerization in bulk and in toluene reveals a relatively small but noticeable solvent effect that can be qualitatively explained by the bootstrap model. Cumulative copolymer composition as a function of conversion is satisfactorily described by the integrated Mayo–Lewis equation; overall copolymerization rate increases with increasing the HEMA/S ratio, and individual monomer conversion is closely related to the monomer molar fraction in the feed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2941–2948, 1999 相似文献
74.
Zhenchuan Wen Xuejian Ma Xiaoyu Yang Pengqing Bi Mengsi Niu Kangning Zhang Lin Feng Xiaotao Hao 《中国化学快报》2019,30(5):995-999
In this work, the donor:acceptor ratio effected photophysical properties of non-fullerene organic solar cells are comparatively investigated. Effective transportation of the photo-generated charge carriers can be obtained with the PDBD-T:ITIC ratio variation. There is no significant energy loss variation exists in the process of changing the D:A ratio. 相似文献
75.
Manuel Snchez‐Chaves Gerardo Martínez Enrique Lpez Madruga Carmen Fernndez‐Monreal 《Journal of polymer science. Part A, Polymer chemistry》2002,40(8):1192-1199
Free‐radical copolymerization of glycidyl methacrylate (GMA) with N‐vinylpyrrolidone (VPD) was carried out at 50 °C using 3.0 mol · L?1 of N,N′‐dimethylformamide solution and 9.0 · 10?3 mol · L?1 of 2,2′‐azobisisobutyronitrile as an initiator. The modification reaction of GMA‐VPD copolymers with a model bioactive carboxylic acid, 6‐methoxy‐α‐methyl‐2‐naphthaleneacetic acid (naproxen), was studied in the homogeneous phase using basic catalysts. The influence of the type of catalyst and the GMA content was evaluated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1192–1199, 2002 相似文献
76.
研究发现在二茂锆-铝氧烷催化体系中添加少量Et2Mg能够明显促进在低Al/Zr摩尔比条件下乙烯高聚.以MAO作为助催化剂,Al/Zr/Mg摩尔比为1012时,得到高聚物,粘均分子量(Mv)为1.37×105,催化活性为2.83×104g聚合物/mol(Zr)h.而在同样的反应条件下,Cp2ZrCl2-MAO和-EAO二组份催化体系在如此低的Al/Zr摩尔比条件下无催化活性或以很低的催化活性生成低碳烯烃.对于这类三组份烯烃高聚催化体系的研究目前仍在进行中,以期得到有效的低Al/Zr比乙烯高聚茂金属催化体系. 相似文献
77.
An efficient computational algorithm to price financial derivatives is presented. It is based on a path integral formulation of the pricing problem. It is shown how the path integral approach can be worked out in order to obtain fast and accurate predictions for the value of a large class of options, including those with path-dependent and early exercise features. As examples, the application of the method to European and American options in the Black–Scholes model is illustrated. A particularly simple and fast semi-analytical approximation for the price of American options is derived. The results of the algorithm are compared with those obtained with the standard procedures known in the literature and found to be in good agreement. 相似文献
78.
79.
The performance of robust artificial neural network models in learning bivariate relationships between accounting magnitudes is assessed in this paper. Predictive performances of a number of modeling paradigms (namely, linear models, log-linear structures, classical ratios and artificial neural networks) are compared with regard to the problem of modeling a number of the most outstanding accounting ratio relations. We conduct a large scale analysis, carried out on a representative Spanish data base. 相似文献
80.
H. P. Benson 《Journal of Optimization Theory and Applications》2007,135(1):1-17
This article presents an algorithm for globally solving a sum of ratios fractional programming problem. To solve this problem,
the algorithm globally solves an equivalent concave minimization problem via a branch-and-bound search. The main work of the
algorithm involves solving a sequence of convex programming problems that differ only in their objective function coefficients.
Therefore, to solve efficiently these convex programming problems, an optimal solution to one problem can potentially be used
to good advantage as a starting solution to the next problem. 相似文献