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Crystallization and enthalpic relaxation studies on a Copolymer of lactic acid

Abdul Aziz, Azizan Bin (2017)
Ph.D. thesis, University of Birmingham.

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The effect of thermal behaviour and properties such as enthalpic relaxation, degree of crystallinity, development of crystallization, crystallization kinetics and melting behaviour of Co-poly (lactic acid) were studied using differential scanning calorimetry (DSC), FTIR spectroscopy and hot stage microscopy. Both glass formation and enthalpic relaxation have been measured on amorphous and partially crystalline samples produced by controlled cooling from the melt and the effect of the degree of crystallinity measured.

Observation of the crystallization in thin films by hot-stage microscopy confirmed that the mechanism was that of the growth of heterogeneously nucleated disc spherulites. Both nucleation density and radial growth rates were measured but they exhibited different temperature dependence.

FTIR spectroscopy has been used to study and characterize the change in structure of Co-PLA with temperature and time. Isothermal crystallization kinetics of Co-PLA was measured in the temperature range from 120 to 136 oc from these changes in the absorption of the IR bands and in particular the intensities of the crystalline and amorphous bands of the carbonyl ester group. In this way it was possible to analyse the kinetics of both primary and secondary crystallization directly from the relative crystallinity over extended periods with sufficient accuracy to test the validity of the Avrami equation.

Type of Work:Ph.D. thesis.
Supervisor(s):Jenkins, Mike and Hay, James N.
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:Metallurgy and Materials
Subjects:TP Chemical technology
Institution:University of Birmingham
ID Code:7808
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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