Papers by Keyword: Reactivity Ratio

Abstract: A new copolymer of acrylamide (AM) and Isobutane-Ethylhexyl acrylate (2-EHA) was synthesized as profile control agent by free radical copolymerization. The copolymer composition obtained by element analysis method led to determination of reactivity ratio by employing YBR calculative method. The result indicated that the reactivity ratios of AM and 2-EHA were 0.856and 0.592 respectively. The chain segment distribution of copolymer was investigated from reactivity ratio and the microstructure of copolymer molecule was analyzed. The results showed that the ratios in feed can hardly change the chain segment distribution. The proportion of 1M1 decreased with the increase of AM in feed. AM and 2-EHA had a tendency to alternate in copolymer chain when f₁=0.286~0.375. The monomer which had a low ratio in feed inserted in copolymer chain with 1M chain segment and the other monomer was separated evenly. It can help to study copolymerization for AM and 2-EHA for industrial production in mass.

Abstract: The control of particle size and its distribution has become more and more important both in theory and in practice of emulsion polymerization field. In this study, cationic styrene-acrylate copolymer containing functional monomer was converted into water-soluble polymers by reaction with quaternising agents and acids with the free-soap emulsion polymerization method. The latex was obtained at the existence of nitrogen by the copolymerization of hydrophobic monomer styrene and 2-ethylhexyl acrylate, hydrophilic monomer dimethylaminoethyl methacrylate, modified PVA-0588 as the emulsifiers. The influences of the amount of azoisobutyronitrile initiator, the amount of dimethyl sulphate quaternising agent, reactivity ratio between monomers, charge density and pH value on the preparation process were discussed. The particle size and particle distribution was strongly affected by these factors. The results showed that the latex with narrow particle distribution and mean particle size about 100nm was obtained under redox system by adjusting 33% monomer to become precursor and dropping the rest of 67% monomer, after polymerization, N,N-dimethylamino groups were fully quaternised with dimethyl sulphate to improve the stability of the solutions. The glass temperature of polymer was 58.1°C, as pH values range of solution was 3~5, the stability and charge density of polymer emulsion could improve.

Abstract: The apparent reactivity ratios of hexafluoropropylene (HFP)/vinylidene fluoride (VDF) emulsion copolymerization were studied by nonlinear fitting according to the copolymer composing equation, which, according to the calculation, are 1.88 and 0.86 respectively. The constitution of mixed gaseous monomers was measured through the gas chromatography. The copolymer compositions before and after reaction were measured by ¹⁹F-NMR. The calculated contents of VDF and HFP have nice accordance with the results from ¹⁹F-NMR analysis, which demonstrates that the method reported here is fairly reliable, and shed a light on the industry-scale consideration for the emulsion copolymerization of HFP and VDF.

Abstract: Free-radical copolymerization of cyclohexyl methacrylate (CHMA) and tetra (ethylene glycol) dimethacrylate (TtEGDMA) were carried out at 60 °C in tetrahydrofuran solution in presence of 2,2-azobisisobutyronitrile. The random copolymers were prepared with nominal crosslinking ratios, X of 1, 5 and 10% mol TtEGDMA / mol CHMA. The copolymers were characterized by 13C NMR spectroscopy. The copolymers was characterized by 13C RMN analysis and determined the copolymers composition. The monomer reactivity ratios r1 (TtEGDMA) and r2 (CHMA) were determined with the linearized copolymerization equations of the Fineman–Ross methods (r1 = 1.77 and r2 = 0.48) and Kelen–Tüdös (r1 = 1.81 and r2 = 0.46). Parameters of Alfrey-Price Q1 = - 1.10 (specific activity) and e1= - 0.64 (polarity) for TtEGDMA.