EMULSION POLYMERIZATION OF VINYL MONOMERS UNDER THE INFLUENCE OF IONIZING RADIATION
The kinetics of emulsion polymerization induced by BETA , gamma , and x radiation are discussed. Such ionizing radiations induce the polymerization of some vinyl monomers in aqueous emulsion with high radiation yields, and with identical emulsion compositions, the kinetics of this reaction and the kinetics of emulsion polymerization induced by water-soluble initiators are very similar. The rate of reaction in emulsion polymerization is approximates 100 times greater than in bulk polymerization. The initiation of emulsion polymerization by means of ionizing radiation permits uniform illumination of the reacting volume, as well as almost any desired variation in the frequency of initiation during the reaction. The sharp decrease in the overall rate of reaction when initiation is interrupted during emulsion polymerization of styrene induced by gamma rays contradicts the earlier concept of sharply separated reaction zones. In addition to examination of the radiation initiated polymerization of styrene, that of methylmethacrylate, ethylacrylate, and vinyl acetate are discussed. Studies made on emulsion polymerization of methylmethacrylate initiated by gamma rays showed that the overall rate of reaction for emulsion polymerization induced was 100-200 times larger thand that in bulk polymerization induced by gamma radiation. An overall rate of reaction of about 11%/min was calculated for a high dose rate from the value measured at the low dose rate. The conversion curve shows that after a steep rise in the overall rate of reaction during the period of particle formation, there follows a short period of zero reaction order. The curve then rises further and attains a max at about 50% conversion. Shortly thereafter it drops sharply, following neither first nor second order kinetics with respect to the monomer concentration in the particles. Ultimately, the high viscosity in the particles at high conversions hinders diffusion in the monomer; at the same time, the polymerization in the aqueous phase has sunk to a very small value, causing a steep decline in the overall rate of reaction. Emulsion polymerization of ethylacrylate at 25 deg C induced by gamma rays at a dose rate of 2 x 10/sup 14/ ev/g/min and a monomer:water ratio of about 1: 7 gave and average molecular wt of the polymer at the end of polymerization of approximates 1.6 x 10/sup 6/. A plot of the logarithm of the overall rate of reaction vs the reaction time reaches a msx 6.5 min after the start of the reaction andd then, without undergoing a period of zero order, falls slowly according to first-order kinetics relative to the monomer concentration. Beyond about 70% conversion, the decline becomes slower. Determination of reaction constants in emulsion polymerization induced by gamma radiation is discussed. (BBB)
- Research Organization:
- Universitat, Cologne
- NSA Number:
- NSA-18-001734
- OSTI ID:
- 4159151
- Journal Information:
- Angew. Chem., Intern. Ed. Engl., Vol. Vol: 2; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ABSORPTION
ACETATES
ACRYLATES
ACRYLIC ACID
ALPHA PARTICLES
BETA PARTICLES
DIAGRAMS
DIFFUSION
EMULSIONS
ENERGY
ENERGY RANGE
ETHYL RADICALS
FLUORINE
GAMMA RADIATION
LOSSES
MAGNETIC FIELDS
MEASURED VALUES
MEMBRANES
METHACRYLIC ACID
METHYL RADICALS
NICKEL
NUCLEAR REACTIONS
NUMERICALS
OSMOSIS
POLYMERIZATION
PROTON BEAMS
REACTION KINETICS
RESONANCE
SOLUTIONS
SPECTROMETERS
STYRENE
TABLES
THORIUM CHLORIDES
THORIUM NITRATES
VINYL RADICALS
VISCOSITY
WATER
X RADIATION