Abstract: A composite structure, particularly a filter structure, is provided comprising a support having a surface and a porous membrane formed integrally to the surface of the support. The support preferably includes means for directing a fluid away from the surface of the support. The support surface is at least slightly soluble in a solvent. The porous membrane comprises a resin soluble in the solvent and precipitated while the casting solution is in contact with a porous substrate and the surface of the support. The membrane is formed and integrally secured to the surface of the support contemporaneously.

Abstract: The invention relates to an apparatus for continuous production of a strand of porous thermoplastic material from preferably pre-expanded granules of said material containing an expanding agent. The apparatus comprises an elongated rectangular channel, two opposite sides of which are formed by the horizontal parts facing one another of two superimposed endless belts moving in a closed path between turning rollers. The granules are introduced through the open intake end of said channel and are expanded to final size and sintered together to a porous coherent strand by means of steam fed between the horizontal belt parts facing one another. The steam and the granules are fed into the channel through individual ducts which are separated from one another and connected to the intake end portion of the channel. Usually, a plurality of granule feeding ducts and a plurality of steam supplying ducts are attached to the intake end portion formed as a box of particular shape.