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Photopolymerization vinyl acetate

Independent estimates of these quantities can be obtained from the temperature coefficients of photopolymerization. If the rate of photoinitiation is assumed to be independent of the temperature, the increase in rate must be due entirely to the change in kp/k] (see Eq. 13), hence the slope of the plot of log Rp against 1/T for the photochemical polymerization should yield Ep — Et/2. Burnett reported the value 5.5 kcal./mole for styrene, and Burnett and Melville found 4.4 kcal./mole for vinyl acetate, in satisfactory agreement with the values given above. [Pg.123]

Pemberton and Johnson [175,176] have performed a thorough study of the photopolymerization of vinyl acetate in aqueous methanol sensitized by ethyl Eosin and ascorbic acid. In agreement with Oster s results, these authors find that polymer is not formed in the absence of oxygen. In addition, dye photobleaching without polymer formation is observed when water is excluded. [Pg.327]

The existence of free radicals was demonstrated by (a) the photopolymerization of vinyl acetate induced by the chlorine atom, and (b) the fading of a solution of triphenylmethyl. [Pg.291]

Some radical initiators decomposing by heat can also be decomposed by UV radiation. Photopolymerization of acrylonitrile in the presence of AIBN or hydrogen peroxide, or of other initiators [75-78] has been reported. The quantum yield of AIBN decomposition is 0.4 at 298 K and 0.6 at 318 K. Photopolymerization of methyl methacrylate, styrene, and vinyl acetate can be initiated by tetramethylsilane, methylchlorosilanes, and halides of Group IV metals [79]. We assume that the radicals are formed by homolytic splitting of the covalent bond... [Pg.90]

In vinyl compound polymerization of vinyl acetate, alcohol, bromide, chloride, or carbonate, ascorbic acid can be a component of the polymerization mixture (733-749). Activators for the polymerization have been acriflavine (734), other photosensitive dye compounds (737,738), hydrogen peroxides (740,741,742), potassium peroxydisulfate (743), ferrous sulfate, and acyl sulfonyl peroxides (747). Nagabhooshanam and Santappa (748) reported on dye sensitized photopolymerization of vinyl monomers in the presence of ascorbic acid-sodium hydrogen orthophosphate complex. Another combination is vinyl chloride with cyclo-hexanesulfonyl acetyl peroxide with ascorbic acid, iron sulfate, and an alcohol (749). Use of low temperature conditions in emulsion polymerization, with ascorbic acid, is mentioned (750,751). Clarity of color is important and impact-resistant, clear, moldable polyvinyl chloride can be prepared with ascorbic acid as an acid catalyst (752) in the formulation. [Pg.472]

Hayashi has investigated in some detail the ionic photopolymerization of styrene monomers. Free ion lifetimes measured by pulse electrical conductivity measurements were found to agree with those calculated from steady-state conductance measurements. Other studies of interest on radical addition polymerization include the photodimerization of polymers containing thymine bases, diene polymerization by terbium complexes, polymerization of vinyl acetate, and preparation of light-sensitive polyacrylates. [Pg.513]

To determine the several rate constants in the photopolymerization of vinyl acetate. [Pg.459]

In the photopolymerization of vinyl acetate under steady illumination at 15.9 °C (Burnett and Melville, Proc. Roy. Soc. A, 1947,189, 456, and see problem 161) the rate of consumption of monomer was... [Pg.464]

Similarly, the rate of photopolymerization of vinyl acetate is affected by solvents. In most cases, however, the rate of polymerization is proportional to the square root of the initiator concentration and to the concentration of the monomer. ... [Pg.48]

Tonnar, J. Pouget, E. Lacroix-Desmazes, P. Boutevin, B., Synthesis of Poly(vinyl acetate)-block-Poly(dimethylsiloxane)-Poly(vinyl acetate) Copolymers by Iodine Transfer Photopolymerization in Microemulsion. Macromol. Symp. 2009,281,20-30. [Pg.211]

Included among the many types of vinyl monomers that have been subjected to photoinitiated cationic polymerization are styrene," substituted styrenes, a-methylstyrenes, N-vinylcarbazole, alkyl vinyl ethers, prop-l-en-l-yl ethers, ketene acetals, and alkoxyallenes. Most useful in the crosslinking photopolymerizations employed for UV curing applications are multifunctional vinyl ethers and multifunctional prop-l-en-l-yl ethers. A number of multifunctional vinyl ether monomers are available from commercial sources, while multifunctional prop-l-en-l-yl ethers can be readily prepared by catalytic isomerization from their corresponding allyl ether precursors. The photoinitiated cationic... [Pg.947]


See other pages where Photopolymerization vinyl acetate is mentioned: [Pg.117]    [Pg.199]    [Pg.326]    [Pg.94]    [Pg.482]    [Pg.527]    [Pg.208]    [Pg.210]    [Pg.403]    [Pg.234]    [Pg.236]    [Pg.207]    [Pg.126]    [Pg.53]    [Pg.95]    [Pg.212]    [Pg.261]    [Pg.283]    [Pg.220]   
See also in sourсe #XX -- [ Pg.327 ]




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