FIELD: polymer materials. SUBSTANCE: porous polytetrafluoroethylene is prepared by bringing polytetrafluoroethylene into contact with fluid medium at heating followed by cooling, separation of impregnated polytetrafluoroethylene from fluid medium, and removal of the latter from product. Process is distinguished by that fluid medium enters polymer to make it swell but does not dissolve it and does not deprive it of its viscous-elastic memory at 250-400 C; cooled product is separated from non-absorbed fluid medium, content of absorbed fluid medium in product being 50 wt % or less, and porous product has one fusion endotherme having temperature range 320-333 C with corresponding melting heat equal to at least 35 J/g. EFFECT: facilitated pore formation and produced new structures. 63 cl, 6 dwg, 8 tbl
