Novel Method for Determination of Polymer–Solvent Interaction Parameter Using Mechanical Properties

Swelling elastomers swell when in contact with certain fluids and are used in different applications in oil drilling and bioengineering. Flory–Huggins polymer-fluid interaction parameter is an important factor that controls swelling. It is conventionally determined by chemical dissociation of the polymer, a difficult and time-consuming method. Current paper focuses on a novel and easier method of estimating this parameter through swelling and mechanical testing. Two different elastomers were kept in saline water of 0.6% and 12% concentration at 50 °C for a period of one month. Changes in mass, volume, density, and elastic and bulk moduli were recorded at different intervals. Shear modulus was used to determine chain density. Density, volume swelling ratio, molar volume, shear modulus, and average chain molecular weight values were used to determine. Both materials showed a decreasing trend in values as swelling progresses, as expected. Value of was higher in high-salinity brine, and larger decrease in value was observed in lower-salinity solution. For instance, in high salinity brine, a drop in χ value from 0.87 to 0.7 was observed for material-A, and a drop from 1.0 to 0.75 for material-B over the 30-day swelling period. In low salinity brine, chi-value decreased from 0.79 to 0.63 for material-A, and from 0.84 to 0.64 for material-B. This work is beneficial for engineers and scientists working on swellable elastomers in particular (petroleum drilling and development), and rubbers and polymers in general.