Abstract: A preparation process of a degradable copolymer comprising carrying out dehydration polycondensation of polysaccharide (A) with one or more compounds (B) selected from the group consisting of:(b1) hydroxycarboxylic acid,(b2) polyhydroxycarboxylic acid,(b3) aliphatic polyhydric alcohol and aliphatic polybasic acid, and(b4) aliphatic polyester derived from aliphatic polyhydric alcohol and aliphatic polybasic acid.A copolymer having a high molecular weight, excellent toughness, transparency and heat resistance, and additionally having a high melt tension can be obtained with a reaction time less than a half of the conventional process. The copolymer obtained by the invention is a material suited for injection molding, extrusion, calendaring, blow forming, balloon forming, vacuum forming and foaming. Particularly, the copolymer obtained by the invention has a high melt tension and thus the molten copolymer is difficult to sag and flow and can be processed with ease into foams and blow bottles.

Abstract: A process for preparing a degradable copolymer of aliphatic polyester comprising the steps of reacting two or more kinds of aliphatic polyester homopolymer in the presence of a catalyst in a reaction mixture containing an organic solvent, and a degradable copolymer of aliphatic polyester obtained by said preparation process. The copolymers exhibits high transparency in addition to excellent strength and elongation, can be processed into various molded articles and formed items such as films and filaments, and can provide heat resistance by heat treatment of said molded articles and formed items. The copolymer can be suitably utilized for processed articles such as a film, breathable film, sheet, textile, monofilament, multifilament, yarn, non-woven fabric, flat yarn, staple, crimped fiber, ribbed tape, split yarn, conjugate fiber, laminate, blow-bottle, sheet, stretched sheet, foam and net.

Abstract: .alpha.-L-Aspartyl-L-phenylalanine methyl ester (.alpha.-APM) is prepared by catalytic hydrogenation of N-benzyloxycarbonyl-.alpha.-L-aspartyl-L-phenylalanine methyl ester (Z-.alpha.-APM). The catalytic hydrogenation is conducted in an aqueous suspension containing the Z-.alpha.-APM in the form of particles whose average particle size is not greater than 800 .mu.m. The starting Z-.alpha.-APM may contain up to 30 wt. % of its .beta.-isomer provided that the process additionally includes recrystallization of the .alpha.-APM, collection of the .alpha.-APM by filtration and recycling of the filtrate for use in the aqueous suspension of Z-.alpha.-APM.