Abstract: Biodegradable hollow fibres with an asymmetric wall, the cavity of which containing an active substance like a drug, hormone etc. or a dilute form of the latter and both ends of the hollow fibre being closed for the controlled release of the active substance as well as a process for the manufacturing of such hollow fibres.

Abstract: Method for preparing a polymer alloy which is stable and homogeneous at high temperatures which comprises a component (a) one or more polymers of high molecular weight, having anhydride groups and component (b) one or more polymers of high molecular weight, having groups which have the ability to interact with hydrogen atoms to form hydrogen bonds. Initially, a solution of component (a) is prepared in an organic solvent and thereafter a solution of component (b) is added. Component (a), in the dissolved state, may be protolyzed in whole or in part, prior to or after the addition of component (b) by the action of protolyzing agents. After the solvent is removed formed products, such as granules, fibres, foils, foam, may be made from the polymer alloy.

Abstract: Method for preparing a polymer alloy which is stable and homogeneous up to high temperatures, from component (a) one or more polymers of high molecular weight, having anhydride groups and component (b) one or more polymers of high molecular weight, having groups which have the ability to interact with hydrogen atoms to form hydrogen bonds, wherein first a solution of component (a) is prepared in an organic solvent, to which solution then component (b) is added, whereas component (a) in dissolved state is protolyzed in whole or in part, prior to or after the addition of component (b) under the action of protolyzing agents, whereupon the solvent is removed; together with the formed products obtained from such a polymer alloy, such as granules, fibres, foils, foam, etc.