Abstract: A method of producing a highly porous melt spun fibrous tube for use as a separation medium comprising melt spinning a blend containing from 30 to 70 parts by weight of a first polymeric component and from 70 to 30 parts by weight of a second polymeric component to form a tube having a wall consisting of interpenetrating networks of the two polymeric components and, using a suitable solvent, leaching out of the tube wall one of the two polymer networks so producing a tube having a wall comprising the other polymer network.

Abstract: A melt spun fiber or tube having two polymeric fibrous components and containing from 30 to 70 parts by weight of a first component and from 70 to 30 parts by weight of a second component, each component being present in the fiber or wall of the tube as fibrils which are substantially aligned to the axis of the fiber or tube the aligned fibrils being interconnected to each other in a random manner, the interconnections penetrating through the fibrils of the other component such that both components exist in the fiber or tube wall as interpenetrating networks.

Abstract: A process of melt spinning polypropylene with a wind up speed of less than 1000 meters per minute in which there is added to the polypropylene a small proportion of a polymer capable of forming an anisotropic melt in the temperature range at which the polypropylene may be melt spun and novel rough surface fibres of polypropylene containing between 0.1% and 10% by weight of the aforementioned polymer.

Abstract: A process of melt spinning a fibre-forming thermoplastic polymer, more particularly polyethylene terephthalate, polyhexamethylene adipamide or polypropylene, at a minimum wind up speed of 2 kilometers per minute in which there is added to the fibre-forming polymer, between 0.1% and 10% by weight of another polymer which is immiscible in a melt of the fibre-forming polymer, such other polymer having a particle size of between 0.5 and 3 microns in the melt with the fibre-forming polymer immediately prior to spinning and novel melt spun fibres produced by such a process and in which the other polymer is in the form of microfibrils.

Abstract: A process of melt spinning polypropylene the improvement comprising adding to the polypropylene before it is melt spun, a small proportion of a polymer capable of forming an anisotropic melt in the temperature range at which the polypropylene may be melt spun and then melt spinning the polymers together at a wind up speed of less than 1000 meters per minute whereby in the process there is a suppression of wind up speed compared with the process carried out in the absence of the added polymer.

Abstract: A process of melt spinning a fibre-forming polymer particularly polyethylene terephthalate or poly-hexamethylene adipamide at a minimum wind up speed of 1000 meters per minute in which there is added to the fibre-forming polymer before spinning a small proportion of a polymer capable of forming an anisotropic melt in the temperature range at which the fibre-forming polymer may be melt spun whereby in the process there is suppression of wind up speed compared with the process carried out in the absence of the added polymer.