A method of producing a porous film comprises subjecting a fibrous material comprised of fibers of a film forming material to conditions of heat and pressure to covert the fibrous material to a porous film. The method allows the production of film material having substantially uniform pore sizes. For example, the pore size distribution of the film may be such as to have a ratio of maximum pore size:mean flow pore of less than 1.2, e.g., less than 1.1.

Method and apparatus for the production of porous tubing. One extrudes a homogeneous mixture of at least two components, one component a meltable polymer and the other component a liquid inert in relation to the polymer, both components forming a binary system which in liquid aggregate state displays a range of complete miscibility and a range with a miscibility gap, at a temperature above the separation temperature, substantially vertically upwardly using a circular slot nozzle and blowing of g...

Porous diaphragms suitable inter alia for electrolytic cells are formed from an aqueous slurry or dispersion of polytetrafluoroethylene and a solid particular additive utilising water as lubricant in the sheet forming operation.

A method of manufacturing porous moulded bodies in which crushed crystaline silicate material is mixed with alkali silicates in the ratio of 2-6:1, the mixture containing 15 percent water by weight of dried substance. The mixture is heated in a closed vessel affording a constant volume system at 140.degree.-500.degree.C so as to avoid the vapour phase and produce a transformation product which is then dried, crushed and heated, if necessary with additives. There is also provided a device for hea...

This invention relates to a porous pavement for parking spaces, roadways, or streets, airfield runways and the like and it provides a porous pavement for such surfaces which allows water to pass through at a high absorption rate, thereby reducing water run-off and reducing flooding, and also allows pollutants to pass through the pavement to the sub-soil, reducing to a great extent the run-off of polluted water to lakes, rivers, bays and oceans. The invention comprises a paving admixture of aggre...

The invention relates to a porous electrode comprising at least a porous catalytic layer containing a catalytically active noble-metal, carbon and a polymeric binder and a porous metallic collector is situated on the electrolyte-side of this layer. According to the invention the catalytic layer has a thickness of less than 80 .mu.m and are the noble-metal particles in the layer situated on the surface and/or in the pores of part of the carbon particles, while the rest of the carbon particles con...

This invention relates to a porous panel for use principally, but not exclusively, for the distribution of a freezing point depressant liquid on an aircraft surface in order to provide protection against atmospheric icing. The panel comprises an outer porous sheet over the surface of which the fluid is to be distributed, a backing sheet of microporous material in contact with one side of the outer sheet, and a sheet of fluid impervious material which is spaced from the microporous sheet. The she...

Porous, lightweight ceramic bodies having a comparatively high strength per unit of weight may be created by first preparing a mixture of hollow glass spheres, a castable ceramic composition including ceramic particles and a binder for such particles and a lubricant such as water, then casting such a mixture to a desired configuration, then allowing the mixture to set up through the action of the binder so as to form a unitary body, and then removing the lubricant from the body. If the binder us...

A process for the manufacture of a porous diaphragm of a synthetic material, especially polytetrafluoroethylene, which comprises forming a sheet of the synthetic material in admixture with a solid particulate additive (eg starch) to be removed therefrom, introducing said sheet into a cell, and removing the solid particulate additive from the sheet by treating the sheet in situ in the cell with an acid (eg hydrochloric acid) containing a corrosion inhibitor (eg propargyl alcohol). The porous diap...

A porous sheet is disclosed that comprises a thin, flexible sheet made of thermoplastic resin having solid particles distributed therein. Small spaces are formed around the particles, such that abrasion or buffing of the opposite surfaces of the sheet causes the formation of a multitude of fine pores that extend through the sheet, making the sheet vapor-permeable but liquid-impermeable.