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181.
Shan Liu Shuhao Qin Zhu Luo Jie Yu Jianbing Guo Min He 《Journal of Macromolecular Science: Physics》2013,52(9):1780-1790
The effect on the notched Izod impact strength of poly(butylene terephthalate) (PBT) by blending it with acrylonitrile-styrene-acrylate (ASA) was examined. Epoxy resin (ER) was demonstrated to be an efficient compatibilizer for the partially compatible blends of PBT/ASA. It requires only a very small amount of ER to improve the toughness of the PBT/ASA blends drastically. Furthermore, there exists an optimum proportion of ER added to achieve maximum notched Izod impact strength. Transmission electron microscopy (TEM) observation suggests that the ER in the PBT/ASA/ER blends suppressing the tendency of coalescence of ASA, leading to better dispersion of the ASA particles. Field emission scanning electron microscopy (FESEM) shows that ER enhances the phase dispersion and the interfacial adhesion between the PBT and ASA phases, it improves the compatibility between PBT and ASA. The compositions in the interphase was continuous, which results in multiphase composites with a graded interphase. It is suggested that enhanced interphase adhesion was necessary to obtain improved dispersion, fine phase morphology, and better toughness. 相似文献
182.
Kai Xiong Yongping Zhu Lianshi Wang Tongmin Cai Anqiang Zhang Xiangbin Zeng 《Journal of Macromolecular Science: Physics》2013,52(7):1351-1369
Poly(ethene-co-1-butene)-graft-methyl methacrylate-acrylonitrile (PEB-g-MAN) was prepared by suspension grafting copolymerization of methyl methacrylate (MMA) and acrylonitrile(AN) onto PEB. PEB-g-MAN/SAN resin blends (ABMS) were prepared by blending PEB-g-MAN with styrene-acrylonitrile copolymer (SAN resin). The effects of AN/(MMA+AN) feed ratio (fAN), PEB/(PEB+MMA+AN) feed ratio (fPEB) and benzoyl peroxide (BPO) dosage on the monomer conversion ratio (CR), rubber's grafting ratio (GR), grafting efficiency (GE) of the copolymerization and the toughening effect of PEB-g-MAN on the SAN resin were investigated. FTIR quantitative analysis showed that when the weight percent of AN unit in the unextracted product was 21.5 wt% with fAN of 25 wt%, the toughening effect of unextracted PEB-g-MAN on SAN resin was the highest. Gel permeation chromatography (GPC) analysis showed that when fAN was 25 wt%, the grafted copolymer had the lowest molecular weight and ABMS had highest toughness. Transmission electron microscopy (TEM) analysis showed that the highest toughness occurred when the phase structure of ABMS was cocontinuous with fAN of 25 wt%. When fAN was 25 wt% PEB-g-MAN domains have numerous small SAN domains in them, which was occlusion structure. Scanning electron microscopy (SEM) analysis indicated that the ABMS fracture surfaces had plastic flow visible, which looked like a craze fibers morphology, for the sample with highest impact strength (fAN = 25 wt%). Dynamic mechanical thermal analysis (DMA) showed that the miscibility of the PEB phase and SAN phase improved after graft copolymerization of MMA and AN onto PEB. 相似文献
183.
ABSTRACT Trace amounts of cerium were analyzed by flow injection kinetic spectrophotometry, based on the decolorization reaction between arsenazo III and Ce(IV) in sulfuric acid medium at room temperature. The absorbance difference (ΔA) of decolorization was linear with the concentration of Ce(IV). The flow injection technique was used to precisely control the timing. Under the optimum conditions, the determination of Ce(IV) in the range 0.0–8.0 µg mL?1 with a correlation coefficient (r) of 0.9982, the regression equation was ΔA = 0.0014 + 0.0406c (µg mL?1). The detection limit (3σ) of 0.2 µg mL?1 was achieved at a sampling frequency of 60 h?1. The proposed method was applied to the analyses of Ce in soil successfully. 相似文献
184.
We propose a method for improving the characteristics of all-optical switching based on azo dye-doped polymers. Using alternately two cross-linearly polarized beams (532 nm, continuous light wave (CW)) to pump azo dye–ethyl red (ER) doped polymer methyl methacrylate (PMMA) film, the modulation depth of the all-optical switching reached 96% at the pump powers of 4.8 mW and 1.6 mW and the modulation frequency of 1000 Hz. For comparison, we used respectively the single linearly polarized beam (4.8 mW) and the alternately linear–circular polarized beams (4.8 mW and 1.6 mW) to pump the film at the modulation frequency of 1000 Hz, the obtained modulation depths of the all-optical switching were 36% and 45.8%, respectively. Furthermore, the experimental measurement and analysis showed that the turn off speed of the all-optical switching could be obviously increased by use of our pump method. 相似文献
185.
186.
An extended descent framework for variational inequalities 总被引:1,自引:0,他引:1
In this paper, we develop a very general descent framework for solving asymmetric, monotone variational inequalities. We introduce two classes of differentiable merit functions and the associated global convergence frameworks which include, as special instances, the projection, Newton, quasi-Newton, linear Jacobi, and nonlinear methods. The generic algorithm is very flexible and consequently well suited for exploiting any particular structure of the problem.This research was supported by the National Science and Engineering Research Council of Canada, Grant A5789, and by the Department of National Defence of Canada, Grant FUHBP. 相似文献
187.
Zhu Daxin 《数学学报(英文版)》1994,10(4):410-414