Ceskoslovenska Akademie Ved

Jiri Zima

Artur Stoy

Vladimir Stoy

Jaroslav Kalal

Miroslav Stol

Vaclav Jungr

The invention relates to a method of manufacturing shaped articles from crystalline or quasi-crystalline acrylonitrile polymers and copolymers, said method consisting in cooling down a solution of said polymer or copolymer in a mixture containing from 50 to 99.5% by weight of a solvent and from 0.5 to 50% by weight of a precipitant to a temperature below the gelation point of the solution until the same gelatinizes, without changing its composition, to the desired shape, whereafter the solvent is removed from the shaped thermoreversible gel thus obtained at temperatures lower than the gelation point of the solution, preferably using a liquid precipitant of polyacrylonitrile miscible with the solvent. It is advantageous to remove the solvent at a temperature which is at least 10.degree. C. lower than the gelation temperature of the polymer solution used. The shaping can be carried out in any convenient way, e.g. using a stationary or rotating mold. Beads, spheres, filaments and foils can be shaped without any mold in the usual way. The method is also suitable for coating surfaces.

Method of manufacturing shaped articles from crystalline acrylonitrile

The invention relates to a new method for manufacturing shaped articles from multi-block copolymers of acrylonitrile with acrylamide and/or acrylic acid, using hot pressure molding, preferably in swelled condition.

Method for manufacturing shaped articles from multi-block copolymers

The invention relates to surgical tubular devices, such as catheters, tracheal or gastric intubation or sounding tubes, tubes for removal of tracheal or pulmonary secretions, and cyctoscopes designed to be temporarily introduced into cavities of living body and consisting of entirely or partially of a hydrophilic copolymer of acrylonitrile with either acrylamide or acrylic acid and, if desired, with a small amount of other co-monomers. The copolymers are swellable in water and aqueous solutions. In the swelled condition they are pliable, elastic and strong. Their properties can be changed by changing the degree of hydrolysis, if the copolymer was prepared by partial hydrolysis of polyacrylonitrile, or by changing the content of hydrophilic units, if the copolymer was obtained by copolymerization of a monomer mixture. The outer layer or surface layer of the part to be introduced into the cavities of living body such as the larynx, trachea, urethra, etc., contains neutralized anions in side-substituents such as carboxylic, sulphonic, sulphuric or phosphoric groups attached to the copolymer main chain by covalent bonds. The part expected to be exposed to the atmosphere during the application to the patient is permanently protected against drying by a layer of a polymer or copolymer impermeable for water and water vapors.

Hydrophilic surgical tubular device

The tendon prosthesis of the invention consists of a core formed of from a synthetic, preferably hydrophilic linear polymer oriented substantially in the direction of the main longitudinal axis of the prosthesis, having a tensile strength exceeding 100 kg/cm.sup.2 and an elastic elongation of 8 - 50 percent, preferably 12 - 25 % of the resting length, and a sheath consisting of one or more layers of a hydrophilic, substantially non-oriented, physically or covalently crosslinked polymer with an equal or higher elastic elongation and an approximately equal or higher hydrophilicity than that of said core. The material of the core and particularly that of the sheath are permanently compatible with living tissue.

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Prague, Czechia

Jiri Zima