EFFECT OF COMPOUND FORMULATION ON THE PRODUCTION AND PROPERTIES OF EPOXIDISED NATURAL RUBBER (ENR-25) FOAMS

In this study, Epoxidized Natural Rubber (ENR-25) formulations are compounded and tested to obtain a stable expandable rubber foam as well as to determine the foam cell physical morphology and its mechanical properties. The experiment was carried out by employing different ratio of rubber blend between ENR-25 and natural rubber (SMR-L), different amount of blowing agent which is Sodium Bicarbonate and different ratio of accelerator between Tetramethylthiuram-disulfenamide (TMTD) and N-cyclohexyl-2-benzotiazolsulfenamide (CBS). Cure characteristics of the compounded rubber were determined using Monsanto Rheometer and the expandable rubber foam is produced using compression moulding technique with utilization of heat transfer process. The generated foam cell morphology is analyzed using image analyzer and SEM while the mechanical properties of the foam are examined by using Instron machine to determine its compression stress. On the other hand, swelling test using the Flory-Rhener equation is also done to support the substitute results. The data shows that at the ratio of 60 phr ENR-25 and 40 phr SMR-L is able to deliver stable rubber foam. Furthermore, increasing the amounts of blowing agent evidently increased the foam cell size, inducing smaller cell in between the foam cell wall, decreasing the value of compression stress and compression set. It was also observed that increasing the ratio of CBS in the compounded rubber will increase the cell size, creating thicker foam cell wall, increasing the value of compression stress and compression set