DEGRADATION OF SOME POLYMER BLENDS

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Date
1983-03
Authors
AVOAJA, ANTHONY GODWIN IHEM
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Abstract
Blends of PVA with PVC, PMMA and PS and PS/PMMA, that cover the entire compositional range have been subjected to outdoor weathering, thermal oxidation and ultraviolet irradiation. With the application of infra-red technique it was possible to detect any structural changes taking place. With the aid of Instron testing instrument it was possible to find out the mechanical modifications that have taken place. The present work investigates the effect of a second polymer on the weathorability of another. The author has observed that in all the cases investigated there was interaction between the dissimilar molecular chains, at least at the phase boundaries, for the two-phase systems. These interactions which may be intermolecular or intramolecular are observed in most cases to have deliterous effects on the structural stability and mechanical properties of the polymers. In a few cases, the interaction reduced the vulnerability of either or both homopolymers to weathering. From the studies it has been observed that PMMA stabilises PVA against outdoor weathering and oven aging, while PVA stabilizes PMMA against ultraviolet degradation. For the PVA/PVC blends general deterioration of property was observed on blending with PVA destabilizing PVC and vice versa, with the effect of PVC on PVA being more pronounced. For the PVA/PS blends, although rigidity was observed to increase with increase in PS in the blends, the presence of PVA was observed to cause general deterioration of mechanical properties, with a minimum in tensile strength, modulus and percentage elongation at 30% PVA in the blends. Vulnerability to thermal degradation was also observed to increase with increase in PVA in the blend. PMMA was observed to destabilize PS to outdoor weathering and on thermal aging all the blends had lower induction periods than the homopolymers. From morphological studies, PVA/PMMA and PS/PMMA were found to be compatible while PVA/PVC and PVA/PS were incompatible
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL, AHMADU BELLO UNIVERSITY, IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF M.Sc. (POLYMER SCIENCE AND TECHNOLOGY) FACULTY OF SCIENCE AHMADU BELLO UNIVERSITY, ZARIA MARCH, 1983
Keywords
DEGRADATION,, POLYMER,, BLENDS.
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