Influence of Mixing schemes on Aging and Permeability of Ketones through Vulcanizates from Low Molecular Weight Natural Rubber Blends

An investigation into how different mixing schemes influences the physico-mechanical properties, aging, sorption, diffusion and permeability of ketones (acetone andcyclohexanone) through vulcanizates from blends of natural rubber (NR) and low molecular weight natural rubber (LMWNR) was reported. The compounding ingredients were mixed with the NR (base polymer) and LMWNR (base polymer) using three different mixing schemes by adopting the semi-efficient sulphur vulcanization compounding formulation. In scheme 1, the natural rubber and LMWNR were first mixed before adding the compounding ingredients. In scheme 2, the compounding ingredients were firstmixedwith the NR before adding the LWMNR and in scheme 3; the compounding ingredients were first mixed with the LMWNR before adding the NR. The physico-mechanical results of the vulcanizates showed that changes in the mixing schemes significantly influence the tensile properties of the vulcanizates. The tensile strengths of the vulcanizates prepared with mixing scheme 2 were 3.5 MPa lower than vulcanizates from scheme 1, while scheme 3 was lower than scheme 1 with 7.8 MPa. The aging result of the vulcanizates from all the mixing schemes were found impressing. The activation energy and free energy change were highest with scheme 1 while the extent of acetone and cyclohexanone penetrations were at lowest with scheme 1, signifying a well crosslinked and ketone resistant vulcanizates.