Study of Thermal and Tensile Properties of the Thermoset Polymer

ABSTRACT

Current advancement in raw material utilization is gradually changing from the conventional petro-based materials into natural materials in order to arrest environmental pollution issue which arises as a result of the non-biodegradability of products obtained from petro-based resources. Plant oil among other alternatives due to its abundance, relatively low cost, non-toxicity and biodegradable nature have been found to be a potential replacement for petro-based feedstock in many industrial application. This study focused on the synthesis of EPKCO-styrene-divinyl benzene thermosetting copolymer. Physicochemical characterization of the crude oil was carried out using standard methods and Epoxidation of the PKCO was carried out using the immobilized candida lipase, Novozyme 435 in 35% H2O2(aq)  at a temperature of 55 0C. The epoxidation of PKCO was monitored using FTIR and NMR. EPKCO, styrene and divinylbenzene were mixed and cured in a Teflon mold. Thermal properties of the EPKCO polymer was carried out using TGA and DSC and the tensile properties of the thermoset polymers was carried out using Instron universal testing machine. The use of Novozyme 435 for the epoxidation of vegetable oil at an optimum temperature of 55 0C has been found to be most suitable for a complete conversion with no side reaction. The FTIR and NMR spectra of the EPKCO showed there was a full conversion of double bonds into oxirane rings with no ring opening reaction occurring, however the degree of conversion to oxirane was found to be lower when the temperature was raised from 55 0C to 65 0C. The derivative curve of the TGA shows that the epoxidation of the PKCO for polymer synthesis improves the thermal stability of the copolymer obtained. EPKCO copolymer is thermally stable up to 300 0C while PKCO polymer has onset degradation temperature at around 250 0C, however, both polymer exhibit similar maximum degradation temperature of 330 0C. The melting temperature for the EPKCO which is taken as the peak of the DSC endotherm is around 110 0C. The tensile properties shows that epoxidation reduces the tensile modulus (rigidity) by 34.84%, tensile stress by 74.16% and and yield stress by 87.3%, consequently, the elongation at break increases by 888.45%. This shows that epoxidation of the oil prior to polymerization increases the flexibility of the material, these properties will be used to tailor the EPKCO polymer for various applications.

EPKCO: Epoxidized Plukenetia Conophora Oil; PKCO: Plukenetia Conophora Oil