EFFECT OF GUM ARABIC ON THE STRUCTURE-PROPERTY RELATIONSHIP IN POLY(VINYL CHLORIDE)
EFFECT OF GUM ARABIC ON THE STRUCTURE-PROPERTY RELATIONSHIP IN POLY(VINYL CHLORIDE)
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Date
2014-05
Authors
IDRIS, SANI ALHASSAN
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Abstract
Gum Arabic exudate was collected from Acacia senegal trees around Zaria metropolis, purified in 95% ethanol and its physical and chemical modifications carried out. Physical modification of the gum involved plasticization of the gum with glycerol and ethylene glycol. The chemical method was performed by acid hydrolysis, acetolysis and acetate formation. Appearance of both modifications was observed after three days of drying. Acetic anhydride (AAN), acetolysis (ACT) and ethylene glycol (EGL) modifications became hard and solid, and were ground to powder. Glycerol (GLY) turned very sticky and acid hydrolysis (AHY) turned into a viscous liquid. From characterization of the samples, all modifications were found to be less dense than the pure gum Arabic sample (PGM). AHY sample was found to be more turbid and has the highest conductivity value followed by AAN sample. pH of all samples was found to be below 7.0, indicating acidic nature of the gums. Melting point measurements showed that all test samples have lower melting point values than the pure gum. FTIR and GC-MS spectra of the pure and chemically modified samples were studied. It was found that there were shifts and absorptions at different frequencies, indicating some degree of interaction between the gum and the modifying solvents. The gums were all mixed with PVC at different compositions and cast into films using tetrahydrofuran as solvent. The films produced were subjected to mechanical tests. The AAN sample has the highest modulus at 10, 20, 30 and 40% gum composition. For PGM, the modulus drops from 10-30% gum composition then finally increases. The ACT modification shows decrease in modulus as the percent of gum increases. Modulus of PGM drops at 20, 40, 60 and 80% gum composition. It was found that the tensile strength of the chemical modification formulations reinforced the PVC matrix at 10%/90%, 20%/80% and 30%/70% gum/PVC compositions for AAN and at 10%/90% and 20%/80% gum/PVC compositions for ACT. Though EGL showed increase at 30%/70% composition, its tensile strength is similar to that of the unmodified gum (PGM), decreasing with increasing gum concentration.
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A Thesis submitted to the School of Postgraduate Studies, Ahmadu Bello University, Zaria, in partial fulfillment of the requirements for the award of Masters Degree in Physical Chemistry. Department of Chemistry, Faculty of Science, Ahmadu Bello University, Zaria, Nigeria.
Keywords
EFFECT,, GUM,, ARABIC,, STRUCTURE-PROPERTY,, RELATIONSHIP,, POLY(VINYL CHLORIDE),