Interaction of Crosslinked EPDM/SBR Blends with Carbonyl Penetrants

Abstract

A series of elastomeric membranes of ethylene propylene diene monomer (EPDM) and styrene butadiene rubber (SBR) blends (wt. ratios, EPDM/SBR - 100/0, 80/20, 60/40, 40/60, 20/80 and 0/100) have been compounded and vulcanized at 150°C. The transport behaviour of carbonyl penetrants like aldehydes; formaldehyde, benzaldehyde, acetaldehyde and ketones; methyl ethyl ketone (MEK), cyclohexanone and acetophenone through EPDM, SBR and their blends have been studied by immersion weight gain method. Transport data are affected by the nature of interacting solvent molecule rather than its size and also by the structural variations of blends. Attempts were made to estimate system parameters like n, which suggests the mode of transport and K is a constant depending on the structural characteristics of the polymer in addition to its interaction with the solvent. The values of n lie in the range 0.48 - 0.71, which suggests that the molecular transport is of Fickian mode. The diffusion co-efficient of all membranes (D) for aldehydes and ketones falls in the range 0.51 - 3.10 x 10 -7 cm 2 /s and 0.27 - 6.02 x 10 -7 cm 2 /s respectively at the temperature range 25 - 60°C. Effect of temperature on sorption (S), diffusion (D) and permeation (P) coefficients were also studied. The temperature dependence of the transport coefficients has been used to estimate the activation parameter for diffusion process (E D ) from the Arrhenius plots. Thermodynamic parameters such as enthalpy (ΔH) and entropy of sorption (AS) have been calculated. Concentration profiles for all the elastomeric membrane-carbonyl penetrants have been computed using a Fickian equation for the appropriate initial boundary.