| abstract |
A composite article having controlled void volume and mean pore size comprises:n (a) polytetrafluoroethylene (PTFE) fibril matrix, and (b) insoluble, non-swellable sorptive particles enmeshed in said matrix, the ratio of non-swellable sorptive particles to PTFE is in the range of 40:1 to 1:4 by weight, the composite article having a porosity in the range of 30 to 80 percent void volume and a mean pore size in the range of 0.3 to 5 micrometers, preferably with at least 90 percent of pores having a size less than 3.6 micrometers. n The article is prepared by incorporating lubricant in the precursor admixture in an amount sufficient to provide a soft dough-like mass and exceed the lubricant sorptive capacity of the particles by at least 3 weight percent and up to an amount at which the mass loses its integrity. |