Porous Polymer Substrates Research Articles

Reverse osmosis characteristics of composite membranes prepared by plasma polymerization of allylamine. Effects of deposition conditions

A study has been conducted to determine the effects of flow configuration and reaction conditions on the performance of composite reverse osmosis membranes prepared by plasma polymerization of allylamine over a porous polymer substrate. It was established that superior membranes were obtained by using a gas-flow configuration avoiding direct monomer flow over the substrate. High rejections of NaCl could be attained when the plasma-deposited film was sufficiently thick to bridge all of the pores in the substrate. It was observed that in addition to influencing the rate of polymerization, the conditions used to sustain the plasma also affected the reverse osmosis characteristics of the deposited film. The effects of these conditions and other preparation procedures are discussed. Attempts to use infrared spectroscopy and ESCA to identify the relationship between polymer structure and reverse osmosis performance were not successful. ESCA did prove useful, though, in confirming an earlier postulated hypothesis that degradation of reverse osmosis performance is associated with the hydrolysis of nitrogen-containing structures in the plasma-deposited film.

Diffusion of liquids in cellulose membranes

AbstractDiffusion of small quantities of liquids in porous polymeric substrates has been studied by means of a radiotracer technique. The procedure has been applied to the permeation of five different types of paper stock by ethylene‐1,2‐C14 glycol. Data obtained indicate that under the experimental conditions the diffusion analogy is valid for solvent penetration in the systems studied. The method should have general applicability to studies of diffusion rates in cellulosic and other membranes and to investigations where only small quantities of diffusant are available.