Determination of initiator decomposition constant in a heterogeneous polymerisation system

✍ Scribed by Sæthre, Bård

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 220 KB
• Volume: 45
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(199802)45:2<222::aid-pi907>3.0.co;2-u

✦ Synopsis

A new method for determination of initiator decomposition constant is described based on the use of instantaneous polymerisation rates for two k d similar experiments run with di †erent initiator concentrations. The constant found will be speciÐc 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 initiated polymerisation of submicron-sized (K 2 S 2 O 8 ) monomer droplets. The monomer droplets were obtained by di †usion 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 was deterk d mined to be 2É5 ] 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 0É50.

1998 SCI.