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Title: Polymerisation of methyl methacrylate in solution
Author: Zafar, Mukhtar M.
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1968
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The rates of polymerisation of methyl methacrylate have been determined in twenty-two solvents. For each solvent, using asobisisobutyronitrile (AZBIT) as initiator, rates have been studied through a range of solvent concentrations. In the case of 1-halogenonaphthalenes the results have been compared with those obtained with a second initiator (azobis-cyclohexanecarbonitrile) at the same temperature. These results have been applied to the theories of Burnett et al., and Henrici-Olive and Olive. Also, in order to ascertain the dependence of the rate of polymerisation on the viscosity of the solvent, the initial gradient of the plots of the rates of polymerisation versus solvent concentration in various solvents have been plotted against the solvent viscosities at 60°C. An attempt has been made to determine the effect of solvent on the propagation coefficient, K , of MMA. An assumption, based on the considerable evidence from the literature, has been made that the product of the viscosity of the solvent/monomer mixture and the termination coefficient, K, is a constant quantity. K- py ratios have been determined from the average kinetic chain tlengths and rates of polymerisation. Using one of the literature values of the termination constant of bulk MIviA at 60°C and the viscosities of the reaction mixtures, theoretical values of the termination constant in solution have been calculated. These K2 xneoretical values of , combined with measured values of have been used to evaluate propagation constants in different solvents at various concentrations. Rates of initiation have been calculated in each case. Using the rotating sector technique and molecular weight measurements, the propagation coefficient and the termination constant have been determined in four solvents (toluene, 1-fluoronaphthalene, 1-chloronaphthalene, 1-bromonaphthalene) at 25°C, using 55a' (by vol.) concentration of MIA. 'These values have been compared with those from bulk MMA. For one of the solvents (chloronaphthalene) K and X, values have also been determined at four different solvent concentrations. Dependence of on the nature and concentration of the solvent and also the relation between solvent/monomer mixture viscosity and the termination coefficient have been K2 investigated. From the knowledge of p/g ratios and the rates of polymerisation, the rates of initiation have also been determined. The results obtained suggest that the enhanced rate of polymerisation observed in several aromatic solvents is due to an increase in the rate of initiation, a decrease in the rate of termination and an increase in the rate constant for propagation. Various explanations to account for these solvent effects have been considered.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available