Abstract: An oriented film with improved tensile strength and Young's modulus can be produced by melting and extruding poly-L-lactic acid and/or poly-D-lactic acid to form a film and, after the film is cooled rapidly, by subjecting it to a stretching process at a temperature above the glass transition temperature and below the cold-crystallization temperature. The stretching may be effected by a method of uniaxial stretching with constant width, successive biaxial stretching or simultaneous biaxial stretching. A thermal treatment may be effected after the stretching process. Films thus obtained have tensile strength over 6 kgf/mm.sup.2 in the stretching direction, Young's modulus over 220 kgf/mm.sup.2 in the stretching direction and transparency to visible light over 90%.

Abstract: Molded articles and method for manufacturing the same from modified casein are disclosed. The casein molded articles are obtained by molding, spinning or casting an aqueous solution of sub-micellular casein from which metal ions have been removed. Fibers, films and other articles made according to the present invention are biodegradeable and have excellent mechanical properties.