By Hattie Ring
T2 NMR relaxation has been demonstrated as a useful tool to understand the interactions between polymers and solvents. Production of poly(vinyl chloride) (PVC) printable wrap films requires creating an organosol with a complex mixture of solvents and additives. Improved understanding of the kinetics of PVC swelling and the interactions between solvents, additives, and PVC can provide insights to improve and extend product performance.
T2 relaxation of organosols were measured using a 20MHz benchtop relaxometer. PVC swelling kinetics were observed from the change in T2 relaxation of organosols over 6 days. Swelling kinetics were characterized and evaluated using variations of PVC printable wrap films formulation. The intermolecular forces between PVC and single solvent systems were compared using the specific relaxation rate enhancement (R2sp ). The R2sp was calculated using the R2 (= 1/T2) of the organosol referenced to the bulk solvent.
The PVC swelling kinetics were determined to follow a two-step process. Variations in temperature and organosol formulation had an impact on the swelling kinetics. The use of R2sp to understand the intermolecular forces and calculate Hanson Solubility Parameters of polymers was also evaluated.