Vinyl acetate

About: Vinyl acetate is a research topic. Over the lifetime, 15970 publications have been published within this topic receiving 162142 citations. The topic is also known as: Ethenyl acetate & Ethenyl ethanoate.

Xanthate-Mediated Living Radical Polymerization of Vinyl Acetate in Miniemulsion

Abstract: The MADIX/RAFT mechanism, employing a xanthate as the reversible chain-transfer agent, has been shown to facilitate the living radical polymerization of vinyl acetate in miniemulsion Methyl (ethoxycarbonothioyl)sulfanyl acetate (MESA) successfully mediated the polymerization which was initiated with either of the water-soluble initiators 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} dihydrochloride (VA-060) or 2,2'-azobis[2(2-dimidazolin-2-yl)propane] dihydrochloride (VA-044) The polymerizations exhibit living characteristics, demonstrated by the evolution of molecular weight distributions The formulation of the miniemulsion produced stable latexes with no coagulum

A detailed on-line FT/NIR and 1H NMR spectroscopic investigation into factors causing inhibition in xanthate-mediated vinyl acetate polymerization

Abstract: Potential sources of inhibition have been investigated via in situ Fourier transform - near infra-red (FT-NIR) and off-line H-1 NMR spectroscopy in the RAFT/MADIX bulk polymerization of vinyl acetate (VA) in the presence of an O-isopropyl xanthate, i.e. methyl (isopropoxycarbonothioyl)sulfanyl acetate. The very high reactivity of the vinyl acetate propagating radical makes it very vulnerable to oxygen, by-products generated during the xanthate synthesis, and stabilizers present as impurities. These impurities induce strong and variable inhibition periods in the polymerization. In addition, the MADIX process, using xanthates as reversible chain transfer agents, has been confirmed to be an efficient method for living VA polymerization. Congruent data are obtained when the monomer consumption with time is followed via both H-1 NMR and in situ FT-NIR spetroscopy. The xanthate-mediated polymerization of VA exhibits no retardation effects and excellent control of the molecular weight distribution can be achieved, leading to poly(VA) of molecular weights exceeding 50 000 g . mol(-1) with relatively low polydispersities.

Determination of Propagation Rate Coefficients by Pulsed-Laser Polymerization for Systems with Rapid Chain Growth: Vinyl Acetate

Abstract: The pulsed-laser polymerization (PLP) technique for determination of free radical propagation rate coefficients (k p ) by GPC analysis has been extended to systems with rapid chain growth. A mathematical model is developed to gain a better understanding of the relative importance of propagation, termination, and transfer events on the leer-generated molecular weight distributions. Insights from the model are used to define appropriate PLP experimental conditions for vinyl acetate (VAc), for which measured k p values are an order of magnitude higher than values measured for styrene and methyl methacrylate at the same temperature

Aqueous colloidal dispersions of polymer

Abstract: Acid fluorides of formula: F(CF2)m -O-[CFX-CF2-O-]n-CFX COF where X is fluorine or perfluoromethyl, m is 1 to 5 and n is 0 or 1 to 10 may be prepared by telomerising tetrafluoroethylene epoxide or hexafluoropropylene epoxide with carbonyl fluoride or a perfluoroalkyl acid fluoride. The products may be hydrolysed with water to the corresponding acids which may be converted to alkali metal and ammonium salts. The preparation of 3, 6-dioxa -2, 4-di(trifluoromethyl) heptafluoroheptanoyl fluoride by telomerising hexafluoropropylene epoxide with carbonyl fluoride in the presence of cesium fluoride is described. The product is hydrolysed with water and treated with ammonia. The acids and salts may be used as dispersing agents in aqueous media. Specifications 673,443 and 752,838 are referred to.ALSO:Stable aqueous dispersions of polymers of at least one monoethylenically unsaturated compound containing as dispersing agent an ionisable compound having a solubility in water of at least 0.1% at 100 DEG C. and having the general formula: F(CF2)m-O-[CF(X)-CF2-O-]n-CF(X)COOA where X is fluorine or trifluoromethyl, m is 1 to 5, n is 0 or 1 to 10 and A is hydrogen, or a monovalent metal or basic radical, may be prepared by polymerizing the monomers in the presence of an aqueous medium containing the said dispersing agent. Specified monomers are vinyl chloride, vinyl fluoride, vinylidene chloride, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, vinyl acetate, vinyl butyrate, acrolein, methacrolein, methyl vinyl ketone, methyl vinyl ether, ethyl vinyl ether, ethylene, propylene, styrene, acrylic acid, methacrylic acid, methyl acrylate, butyl acrylate, ethyl methacrylate, acrylamide, methacrylamide, acrylonitrile, itaconic acid, dimethyl fumarate, diethyl fumarate and vinyl pyridine. Polymerization may be effected in the presence of initiators such as persulphates, perborates, percarbonates, hydrogen peroxide, disuccinic acid peroxide, disodium azobis (g -cyanovalerate) and azobisisobutyramidine hydrochloride. Examples describe the polymerization of tetrafluoroethylene in the presence of disuccinic acid peroxide, iron powder, paraffin wax and dispersing agents of formulae (I) CF3 CF2 CF2-O CF(CF)3 CF2-OCF(CF3) COONH4, (II) CF3 CF2-OCF(CF3)CF2 OCF(CF3) COONH4, (III) CF3-OCF (CF3) CF2OCF(CF3)-COONH4, (IV) CF3 CF2 CF2 OCF (CF3) CF2 OCF(CF3) COONH3CH3, (V) CF3 CF2 CF2 -OCF(CF3) CF2 OCF (CF3) COONH2 (CH3)2, (VI) CF3 CF2 CF2 OCF (CF3) CF2 OCF (CF3) COONH (CH3)3, (VII) CF3 CF2 CF2 -OCF (CF3) CF2 OCF (CF3) COON (CH3)4, (VIII) CF3 CF2 CF2 OCF-(CF3) CF2 OCF (CF3) COO NH3 CH2 OH, (IX) CF3 CF2 CF2-OCF (CF3) CF2 OCF (CF3) COONa, (X) CF3-CF2 CF2 O [CF (CF3) CF2O]2 CF (CF3)-COONH4, (XI) CF3 CF2 CF2 O [CF (CF3) CF2O]3, CF (CF3) COONH4, (XII) CF3 CF2-CF2 OCF (CF3) COOH, (XIII) CF3 CF2 CF2-OCF (CF3) CF2 OCF (CF3) COOH, (XIV) CF3 CF2 CF2 O[CF(CF3) CF2O]2 CF(CF3)-COOH, and (XV) CF3 CF2 CF2 O[CF(CF3)-CF2O]3 CF (CF3) COOH; the copolymerization of tetrafluorethylene and hexafluoropropylene in the presence of disuccinic acid peroxide, iron powder, paraffin wax and dispersing agents of formulae (XVI) CF3 CF2 O CF2 CF2 OCF2-COONH4, (XVII) CF3 CF2 O[CF2 CF2O]2 CF2 COONH4 and (XVIII) CF3 CF2 CF2O-CF (CF3) CF2 O CF (CF3) COONH4; and the polymerization in the presence of potassium persulphate and ammonium 3, 6-dioxa -2, 4-di(trifluoromethyl) undecafluorononanoate of (XIX) chlorofluoroethylene in the presence of paraffin wax, (XX) styrene, (XXI) acrylonitrile, (XXII) vinyl acetate and (XXIII) tetrafluoroethylene and hexafluoropropylene. The dispersions may be used for making fibres and films and for coating wood, metal, ceramics and textiles. Specifications 673,443 and 752,838 are referred to.