Preparation of polycarbonate microfilters by nuclear tracking-chemical etching technique

Abstract

Track-etched PC microfilters have been successfully prepared by first irradiating 13-micron polycarbonate films with fission fragments from uranium (U-235) in a nuclear reactor and subsequently subjecting the treated films through an etching procedure in order to enlarge the radiation-induced damaged tracks to produce a porous structure in the finished films. Varying the irradiation time in nuclear reactor and the average pore diameter by varying the etching conditions can readily control the porosity of the filters. In this work, the as-prepared microfilters had the average pore diameter ranging from ca. 0.486 to 9.514 micrometers and the pore density ranging from 50,000 to 155,000 pores per square centimeter. However, the thickness of microfilter was found decreasing with increasing pore diameter. This study focuses on the effects of etching conditions on the mechanical integrity of the as-prepared filters. It was found that the tensile strength, yield strength and modulus decreased with porosity but % elongation was increased. Fourier transformed infrared spectroscopy (FTIR) results suggested some modifications to the chemical structure after fission fragment tracking and chemical etching. The water permeability seems increasing with increasing pore diameter of track-etched PC microfilters