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Determination of initiator decomposition constant in a heterogeneous polymerisation system
Author(s) -
Sæthre Bård
Publication year - 1998
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/(sici)1097-0126(199802)45:2<222::aid-pi907>3.0.co;2-u
Subject(s) - monomer , polymerization , thermal decomposition , vinyl chloride , polymer chemistry , reaction rate constant , isothermal process , decomposition , emulsion polymerization , chemistry , reaction calorimeter , chemical engineering , materials science , kinetics , polymer , copolymer , thermodynamics , organic chemistry , calorimetry , physics , quantum mechanics , engineering
A new method for determination of initiator decomposition constant k d is described based on the use of instantaneous polymerisation rates for two similar experiments run with different initiator concentrations. The constant found will be specific for the polymerisation system used. If the propagation and termination rate constants for the monomer are known from other studies the initiator efficiency factor f can then be obtained. To verify the validity of the method, poly(vinyl chloride) latexes were prepared by potassium persulphate (K 2 S 2 O 8 ) initiated polymerisation of submicron‐sized monomer droplets. The monomer droplets were obtained by diffusion of vinyl chloride monomer into a preformed emulsion of water‐insoluble oil droplets. The polymerisation was performed in an isothermal calorimeter. From the measured heat evolution, the instantaneous polymerisation rates were calculated. The thermal decomposition constant of potassium persulphate k d was determined to be 2·5×10 ‐6 s ‐1 at 51°C. In the same system the order of reaction with respect to the initiator concentration was found to be 0·50. © 1998 SCI.