Gas transport in vulcanized natural rubber-cellulose. II. Composites

This work reports the transport of carbon dioxide, oxygen, and nitrogen in amorphous membranes of vulcanized natural rubber reinforced with regenerate d cellulose. The values of the permeability coefficient of carbon dioxide, oxygen, and nitrogen in the composites with 25% of cellulose, measured at 2 5 degrees C and 15 cmHg of pressure, are roughly one-third of those measure d in the same conditions for these gases in natural rubber. The isotherms r epresenting the variation of both the permeability and diffusion coefficien ts of the gases with pressure present a relatively sharp increase in the re gion of low pressures, attributed to changes in the free volume. The analys is of the permeability characteristics of the membranes in terms of the fre e-volume theory suggests that gas transport is severely hindered in both th e cellulose phase and the cellulose-rubber interphase of the composites. (C ) 2000 John Wiley & Sons, Inc.