Development of kevlar-supported novel polypropylene membranes: Effect of the concentration of the nucleating agent on the properties and performance

Novel membranes were fabricated with woven Kevlar fabric sandwiched between two isotactic polypropylene layers and with various concentrations of adipic acid as the nucleating agent (NA). A thermally induced phase-separation dip-coating method was adopted to generate and control the microporosity in the developed membranes. Scanning electron microscopy and atomic force microscopy were used to directly observe and confirm the morphologies and micropores in the fabricated membranes. We observed that with an increase in the concentration of the NA in the fabricated membranes, both the pore density and pore size decreased. The average pore sizes were observed to be 1.686, 0.925, 0.372 m, respectively, for 0.3, 0.5, and 0.7 pphr concentrations of the NA, respectively. The flux characteristics of the prepared membranes were also tested at various pressures with water, methanol, ethanol, and isopropyl alcohol as solvents in a custom-made filtration cell. The results obtained indicate the dependence of the flux on the type of solvent, pressure, and membrane. The flux for the solvents was observed to decrease with increasing concentrations of NA in the prepared membranes and was attributed to the decrease in the pore density and pore size. (c) 2013 Wiley Periodicals, Inc.