Study of Chemical Absorption and Swelling Kinetics at 50 ° for Polyurethane/ Montmorillonite Clay Nanocomposites
Abstract
Layered silicate composites having polyurethane matrix were prepared by in situ polymerization. Montmorillonite clay was pretreated with centyl tri-methyl ammonium bromide (CTAB) to convert hydrophilic clay into organophilic MMT so that it is compatible with hydrophobic polyurethane matrix. The composites so prepared were characterized for their morphology using SEM and chemical absorption in various chemicals like toluene, ethyl acetate, xylene, hexane, methanol, DMF, tetrahydrofuran, acetone, petroleum ether, distilled water, saline water, and ethanol with varying solubility parameters. The absorption study revealed that depending upon the absorption the solvent can be divided into three categories, high absorbing, medium absorbing and low absorbing depending upon their solubility parameters vis-a-vis polyurethane resin. Two high absorbing solvents i.e. ethyl acetate and xylene, one medium absorbing i.e. ethanol and one low absorbing i.e. saline water here taken to further study the swelling kinetics at 50°C to establish its barrier properties and diffusivity. For all the solvents, the presence of montmorillonite layers caused a decrease in permeability due to more tortuous path for diffusing molecules that must by pass impermeable platelets.
Authors
Roopa Gera, Anupama Sharma