STUDIES ON THE THERMODYNAMIC PROPERTIES OF NATURAL RUBBER COMPOSITES FILLED WITH CLAY AND CORN COB

Abstract

The mechanical properties of materials such as natural rubber composites determine their usefulness as engineering or biological materials. The thermodynamic properties of natural rubber composites filled with clay and corn cob at varying volume fraction of filler were studied with a view of relating and comparing thermodynamic parameters (ΔG, ΔH and ΔS) to mechanical properties (Young’s modulus, tensile strength, elongation at break, etc) of natural rubber composites. The rubber composites were prepared using a standard compounding recipe. The tension observed for each rubber composite as a result of changes in temperature was used in evaluating thermodynamic parameters via Arrhenius equation and plot. These properties have been evaluated by measuring the thermodynamic parameters of natural rubber composites compounded with varying percent volume fractions (5% - 25%) of two fillers- clay and corn cob. The results indicated that the maximum values of ΔG and ΔH was obtained for corn cob filled composites at 10% volume fraction, while the optimal values of ΔS for the same composites was found to be at 5% and 25% volume fraction. At lower filler concentration (5 – 17.5%), corn cob filled composites were observed to have higher modulus than clay filled rubber composites, while at these concentration ranges, clay was found to impact higher tensile strength to natural rubber than corn cob filler.