Photosensitized polymerization of vinyl acetate under high pressure

Yokawa, Masaru; Ogo, Yoshiaki

doi:10.1002/macp.1976.021770211

Cited by 31 publications

(7 citation statements)

References 8 publications

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“…[166] The only exception is radical recombination in the termination step of polymerizations. [167] These reactions possess DV°values in the range of + 13 to + 25 cm 3 mol À1 , which are composed of the large and positive contribution of the diffusion and the small and…”

Section: à N Coupling Through Semiconductor Photocatalysismentioning

confidence: 99%

Semiconductor Photocatalysis—Mechanistic and Synthetic Aspects

2012

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Preceding work on photoelectrochemistry at semiconductor single-crystal electrodes has formed the basis for the tremendous growth in the three last decades in the field of photocatalysis at semiconductor powders. The reason for this is the unique ability of inorganic semiconductor surfaces to photocatalyze concerted reduction and oxidation reactions of a large variety of electron-donor and -acceptor substrates. Whereas great attention was paid to water splitting and the exhaustive aerobic degradation of pollutants, only a small amount of research also explored synthetic aspects. After introducing the basic mechanistic principles, standard experiments for the preparation and characterization of visible light active photocatalysts as well as the investigation of reaction mechanisms are discussed. Novel atom-economic C-C and C-N coupling reactions illustrate the relevance of semiconductor photocatalysis for organic synthesis, and demonstrate that the multidisciplinary field combines classical photochemistry with electrochemistry, solid-state chemistry, and heterogeneous catalysis.

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Section: à N Coupling Through Semiconductor Photocatalysismentioning

confidence: 99%

Semiconductor Photocatalysis—Mechanistic and Synthetic Aspects

2012

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“…For vinyl polymerizations, considerable research (5)(6)(7)(8)(9)(10)(11)(12)(13)(14) has been directed toward the effect of pressure up to hundreds of MPa on the early stage of reaction rate. The pressure dependence of reaction rate constants associated with initiation, chain propagation, and bimolecular termination has been related by the transition state theory (15) dlnk/dp= -AV"/RT (1) where k is the rate constant, AV* is the activation volume, R is the gas constant.…”

Section: Introductionmentioning

confidence: 99%

“…for initiation by the thermal decomposition of a n initiator ranges from + 4 to + 13 cm3/mole (5)(6)(7), whereas AV; for propagation is in the range of -15 to -24 cm3/mole for most monomers (8)(9)(10)(11). AV; for bimolecular termination is positive with val-ues that are generally in the range of + 13 to + 2 5 cm3/mole (8)(9)(10)(11). This is due to the fact that the termination step is diffusion-controlled, increased pressure decreases k, by increasing the viscosity of the reaction medium (12)(13)(14).…”

Section: Introductionmentioning

confidence: 99%

Curing of unsaturated polyester resins—effects of pressure

Huang¹,

Lu²,

Hwu³

1993

Polymer Engineering & Sci

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The effects of pressure ranging from 0.1 to 6.21 MPa (0-900 psi@ on the curing of unsaturated polyester resins at 110°C were invtstigated by an approach of integrated reaction kinetics-rheology-morphology measurements using a pressure differential scanning calorimeter (DSC), an infrared spectrophotometer (IR), a Haake rheometer, and by using scanning electron microscopy (SEM). Increasing pressure was found to delay the gel effect, and a previously unknown plateau of kinetic-controlled region in the initial portion of the DSC rate profile was observed. The plateau region was mainly attributed to the crosslinking of C= C double bonds inside the microgel particles, as revealed by the conversions of styrene and polyester C = C bonds measured by IR, gel conversion data and SEM micrographs. The mechanisms of reaction kinetics both at atmospheric pressure and under pressures have also been elucidated by the progress of buildup of microgel structures.

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“…For propagation a joined fit of the data of Buback [12] and Hutchinson [13] is used. To describe the termination, data from Yokava and Ogo [14,15] together with Pernecker and Foldes-Berezsnich [16] are jointly fitted. The rate coefficients for the transfer to monomer are also derived from a combined data fit.…”

Section: Simulation Modelmentioning

confidence: 99%

Modeling the Chain‐Length Differentiated Polymer Microstructure of α‐Olefins

Busch

Becker

2007

Macromolecular Symposia

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Summary: Due to a complex polymerization scheme, incorporating besides propagation, termination and transfer to monomer and chain transfer agents in addition intra-and inter-molecular transfer to polymer as well as b-scission, a-olefin (co)polymers feature a quite complex polymeric microstructure. It is demanding to design a kinetic model that describes these in a predictive manner in order to have a tool for computer-aided product design. The molecular weight distribution and branching indices together with the composition are the subjects of interest in this case. The latter quantities are often provided as being averaged over the molecular weight distribution. Modern coupled analytical techniques of size exclusion chromatography provide even more insight. The combination of size exclusion chromatography with fractionation techniques provide under adequate processing of the data branching indices and co-polymer composition differentiated with respect to chainlengths. This contribution will inspect how good a model for predicting the chain-length differentiated co-polymer composition in high-pressure hightemperature ethene -vinyl acetate-co-polymerizations will coincide with analytical results of technical products.

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Photosensitized polymerization of vinyl acetate under high pressure

Cited by 31 publications

References 8 publications

Semiconductor Photocatalysis—Mechanistic and Synthetic Aspects

Semiconductor Photocatalysis—Mechanistic and Synthetic Aspects

Curing of unsaturated polyester resins—effects of pressure

Modeling the Chain‐Length Differentiated Polymer Microstructure of α‐Olefins

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