The coarsening process of the droplets in two\|phase polymer blend system was studied under 2\|dimensional conditions using a phase contrast microscope and computer image analyzer.It was found that the substrate (glas...The coarsening process of the droplets in two\|phase polymer blend system was studied under 2\|dimensional conditions using a phase contrast microscope and computer image analyzer.It was found that the substrate (glass) has significant effect on the phase separation and droplets coarsening process.The interfacial interaction(wetting effects)will accelerate the droplets coarsening process when one phase has stronger affinity to the substrate than another phase,and the growth of the droplets radius with time follows r\+3～t\+a a >1.On the other hand,when there is almost the same interaction between the dispersed phase and the matrix with the substrate,i.e.the two phases have the same wettability to the substrate (such as the system of PP/PE),no effect of the substrate on the coarsening process of the droplets was observed,i.e.the growth law is r\+3～t according to Ostwald ripening theory.It is expected that there is a critical value for the interfacial tension between the components of blends under 2\|D condition.The growth law of the dispersed phase changes\|over above or below the critical point.展开更多
Amphoteric polyacrylamide was prepared first by the copolymerization of acrylamide with sodium acrylate and then through Mannich reaction.The copolymerization was carried out with a redox initiation system using the ...Amphoteric polyacrylamide was prepared first by the copolymerization of acrylamide with sodium acrylate and then through Mannich reaction.The copolymerization was carried out with a redox initiation system using the method of inverse emulsion polymerization.In this paper the reaction conditions and factors that affect emulsion stability were studied.Experiments show that a stable latex can be obtained under the following conditions:anionic degree is five percent,the ratio among acrylamide,formaldehyde and dimethylamine is 1∶1∶1.2,reaction temperature is 45 ℃,reaction time lasts four hours,and pH equals 5.0.The amphoteric copolymer has a higher molecular weight and cationic degree,so it is an ideal filler retention and drainage aid in paper making.展开更多
Monte Carlo simulations were used to investigate the compatibilizing behaviors of multi-block copolymers with different architectures in A/B/（block copolymer） ternary blends. The volume fraction of homopolymer A, em...Monte Carlo simulations were used to investigate the compatibilizing behaviors of multi-block copolymers with different architectures in A/B/（block copolymer） ternary blends. The volume fraction of homopolymer A, employed as the dispersed phase, was 19%. The simulations illustrate how a di- or multi-block copolymer aggregates at the interfaces and influences the phase behaviour of such incompatible polymer blends. The di-block copolymer chains tend to ＂stand＂ on the interface whereas the multi-block chains lie on the interface. In comparison with the di-block copolymer, the block copolymers with 4, or 10 blocks can occupy more areas on the interface, and thus the multi-block copolymers have higher efficiency for the retardation of the phase separation.展开更多
A bicentral polymer-supported Phase transfer catalyst, polystpyne-suPPorted polyethylene glycol and Pyridinium salt (PS-Py-PEG-400),synthesized with ohloromethylated polystyrene as supporter on which PEG and Pyridiniu...A bicentral polymer-supported Phase transfer catalyst, polystpyne-suPPorted polyethylene glycol and Pyridinium salt (PS-Py-PEG-400),synthesized with ohloromethylated polystyrene as supporter on which PEG and Pyridinium salt were immobilized successively. Its catalytic activity was tested for the reauction of solid potassium acetate and benzyl bromide by GC analysis. It was found that the bicentral catalyst performed higher activity than the monocentral PS-PEG-400 and PS-Py.展开更多
文摘The coarsening process of the droplets in two\|phase polymer blend system was studied under 2\|dimensional conditions using a phase contrast microscope and computer image analyzer.It was found that the substrate (glass) has significant effect on the phase separation and droplets coarsening process.The interfacial interaction(wetting effects)will accelerate the droplets coarsening process when one phase has stronger affinity to the substrate than another phase,and the growth of the droplets radius with time follows r\+3～t\+a a >1.On the other hand,when there is almost the same interaction between the dispersed phase and the matrix with the substrate,i.e.the two phases have the same wettability to the substrate (such as the system of PP/PE),no effect of the substrate on the coarsening process of the droplets was observed,i.e.the growth law is r\+3～t according to Ostwald ripening theory.It is expected that there is a critical value for the interfacial tension between the components of blends under 2\|D condition.The growth law of the dispersed phase changes\|over above or below the critical point.
文摘Amphoteric polyacrylamide was prepared first by the copolymerization of acrylamide with sodium acrylate and then through Mannich reaction.The copolymerization was carried out with a redox initiation system using the method of inverse emulsion polymerization.In this paper the reaction conditions and factors that affect emulsion stability were studied.Experiments show that a stable latex can be obtained under the following conditions:anionic degree is five percent,the ratio among acrylamide,formaldehyde and dimethylamine is 1∶1∶1.2,reaction temperature is 45 ℃,reaction time lasts four hours,and pH equals 5.0.The amphoteric copolymer has a higher molecular weight and cationic degree,so it is an ideal filler retention and drainage aid in paper making.
基金ACKN0WLEDGMENT This work was supported by the National Natural Science Foundation of China （No.20374050） and SRFDP （No.20050358018）.
文摘Monte Carlo simulations were used to investigate the compatibilizing behaviors of multi-block copolymers with different architectures in A/B/（block copolymer） ternary blends. The volume fraction of homopolymer A, employed as the dispersed phase, was 19%. The simulations illustrate how a di- or multi-block copolymer aggregates at the interfaces and influences the phase behaviour of such incompatible polymer blends. The di-block copolymer chains tend to ＂stand＂ on the interface whereas the multi-block chains lie on the interface. In comparison with the di-block copolymer, the block copolymers with 4, or 10 blocks can occupy more areas on the interface, and thus the multi-block copolymers have higher efficiency for the retardation of the phase separation.
文摘A bicentral polymer-supported Phase transfer catalyst, polystpyne-suPPorted polyethylene glycol and Pyridinium salt (PS-Py-PEG-400),synthesized with ohloromethylated polystyrene as supporter on which PEG and Pyridinium salt were immobilized successively. Its catalytic activity was tested for the reauction of solid potassium acetate and benzyl bromide by GC analysis. It was found that the bicentral catalyst performed higher activity than the monocentral PS-PEG-400 and PS-Py.
