u s pat nos 4 153 661 4 460 642 and 5 071 610 the processes of which are incorporated herein by reference by blending the desired particulate into the aqueous ptfe emulsion in the presence of sufficient lubricant to approach meet or preferably exceed the sorptive capacity of the solids yet maintain a putty like consistency this putty like mass is then subjected to intensive mixing at a temperature between 0 u00b0 and 100 u00b0 c preferably between 40 u00b0 and 100 u00b0 c to cause initial fibrillation of the ptfe particles thereafter the putty like mass is repeatedly and biaxially calendered with a progressive narrowing of the gap between the rollers until shear causes the ptfe to fibrillate and enmesh the particulate and a layer of desired thickness is obtained removal of any residual surfactant or wetting agent by organic solvent extraction or by washing with water after formation of the sheet article is generally desirable the resultant sheet is then dried such sheets generally have thicknesses in the range of 0 05 to 10 mm preferably in the range of 0 1 to 1 mm most preferably in the range of 0 1 to 0 5 mm if a web with multiple particulate layers is desired the component layers themselves are placed parallel to each other and calendered until they form a composite where the ptfe fibrils of the separate layers are entwined at the interface of adjacent.