The Copolymerisation Of Styrene And Methyl Methacrylate, Styrene And Butyl Acrylate
Published 2010 · Chemistry
The copolymerisations of styrene and methyl methacrylate, styrene and butyl acrylate, induced by the photo decomposition of benzoyl peroxide, have been studied and a full kinetic analysis of the reaction is presented. The introduction of small amounts of styrene lowers both the rate of initiation and the rate of copolymerisation to a marked extent, but further additions of styrene have relatively little effect. From a knowledge of the rate of initiation, derived from osmotic molecular weight data, and the overall rate, all the rate coefficients for the copolymerisations have been calculated. The termination constant for the reaction between styrene and methyl methacrylate radical (ktab = 2.06. 108) is much larger than that for styrene (ktaa = 8. 106) or methyl methacrylate (ktbb = 2.7. 107). Similarly for styrene (A)-butyl acrylate (B), ktab = 5.7. 107 is much larger than ktaa = 8. 106 or ktbb = 1.8. 104. The derivation of these velocity constants is discussed critically, and a possible explanation of the large “crossed” termination constant, ktab, is offered, in terms of polar attractions of the two radicals.