Kinetic studies on the polymerisation of vinyl acetate in the presence of solvents

Sattar, Abdul (1967) Kinetic studies on the polymerisation of vinyl acetate in the presence of solvents. PhD thesis, University of Glasgow.

Abstract

The kinetics of the polymerisation of vinyl acetate in the presence of solvents has been studied. Azobis isobutyronitrile has been used as photoinitiator. As little as 5% of benzene lowers the rate of polymerisation of vinyl acetate to about one-half its value in the absence of benzene. For the polymerisation of vinyl acetate alone and of various benzene/vinyl acetate mixtures the rates of polymerisation, molecular weights and chain transfer constants over the temperature range 25-60°C have been measured. The intensity exponents were found to be in the region of 0.51-0.54 both with benzene and in its absence. Labelled benzene, grown as a single crystal, has been used at different temperatures to find out the number of benzene molecules Incorporated in each polymer chain, and on an average one molecule of benzene has been found per polymer molecule. A possible mechanism for the polymerisation of vinyl acetate in the presence of benzene has been put forward. The rate of polymerisation of vinyl acetate in the presence of toluene has been found the same as in the presence of benzene. Greater retardation was observed in the presence of cyclohexadiene and also the lowering of molecular weight of the polymer formed. Termination was found to be second order with respect to the growing polymer radical concentration. The effect of other solvents (mainly substituted benzenes) on the polymerisation of vinyl acetate was studied and different rates of reaction have been explained by steric hinderance. The rate of polymerisation of vinyl acetate was very much retarded by styrene which has been shown to copolymerise with vinyl acetate. Labelled styrene and labelled vinyl acetate were used in turn to evaluate the monomer reactivity ratios. Velocity coefficients for propagation termination, and kinetic chain lifetime for the polymerisation of vinyl acetate in the presence of small amounts of styrene have been determined using the thermocouple method. The value of kp was found to decrease with increase in styrene concentration, while that of kt remained unchanged.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: Dr. W. I. Bengough.
• Keywords: Polymer chemistry.
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering > School of Chemistry
• Date of Award: 1967
• Depositing User: Enlighten Team
• Unique ID: glathesis:1967-73320
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Jun 2019 08:56
• Last Modified: 11 May 2022 16:18
• Thesis DOI: 10.5525/gla.thesis.73320
• URI: https://theses.gla.ac.uk/id/eprint/73320