Abstract: A method of preparing a gel from carboxymethyl cellulose alkali metal salt, which is an anionic cellulose derivative, by using acid or acid solution. To increase the strength and the elasticity of a gel, a water-insoluble metal compound or organic reinforcement is added when mixing. The obtained gel is one of environmentally friendly type gels because the raw material is derived from plant.

Abstract: A biodegradable aliphatic polyester, such as polylactic acid, is mixed with a monomer having allyl and molded into a molding having the crosslinking degree of the biodegradable aliphatic polyester increased. Thereafter, the molding is exposed to ionizing radiation to thereby obtain a molding excelling in heat resistance. Triallyl isocyanurate or triallyl cyanurate is used as the monomer having allyl.

Abstract: A method of preparing a gel from carboxymethyl cellulose alkali metal salt, which is an anionic cellulose derivative, by using acid or acid solution. To increase the strength and the elasticity of a gel, a water-insoluble metal compound or organic reinforcement is added when mixing. The obtained gel is one of environmentally friendly type gels because the raw material is derived from plant.

Abstract: A process for producing a chitin derivative and/or a chitosan derivative that have a crosslinked structure, which comprises irradiating a paste of a mixture consisting of 100 parts by weight of a chitin derivative and/or a chitosan derivative and 3˜1,000 parts by weight of purified water.

Abstract: A process for producing a self-cross-linking alkyl cellulose derivative, which includes irradiating, with radioactive rays, a mixture of a starting alkyl cellulose derivative (the number of carbon atoms of the alkyl group is 1 through 3, the alkyl group may be substituted by a hydroxyl group or a carboxyl group, and the carboxyl group may form a salt) (100 parts by weight) and water (5–2,000 parts by weight), and thus obtained self-cross-linking alkyl cellulose derivative has an improved biodegradability and excellent water-absorbability.

Abstract: A biodegradable aliphatic polyester, such as polylactic acid, is mixed with a monomer having allyl and molded into a molding having the crosslinking degree of the biodegradable aliphatic polyester increased. Thereafter, the molding is exposed to ionizing radiation to thereby obtain a molding excelling in heat resistance. Triallyl isocyanurate or triallyl cyanurate is used as the monomer having allyl.

Abstract: The invention provides a process for producing a transparent polyactic acid material, comprising the steps of: kneading a polyactic acid with a monomer having two or more double bonds in its molecule; molding the kneaded product at a temperature of from the melting point of the polyactic acid to 200° C. to obtain a molded article; quenching the molded article after molding; and subjecting the quenched molded article to crosslinking treatment so as to prevent molecules of the polylactic acid from undergoing recrystallization. Also disclosed is a transparent polyactic acid material produced by the process.

Abstract: A process for producing a self-cross-linking alkyl cellulose derivative, which includes irradiating, with radioactive rays, a mixture of a starting alkyl cellulose derivative (the number of carbon atoms of the alkyl group is 1 through 3, the alkyl group may be substituted by a hydroxyl group or a carboxyl group, and the carboxyl group may form a salt) (100 parts by weight) and water (5-2,000 parts by weight), and thus obtained self-cross-linking alkyl cellulose derivative has an improved biodegradability and excellent water-absorbability.

Abstract: An adsorbent for recovering useful rare metals in solution by adsorption is synthesized by forming reactive sites on a polymeric base material at first, then polymerizing reactive monomers at the reactive sites of the polymeric base material by graft polymerization, thereby forming graft chains, and introducing chelate-forming groups into the graft chains, where the polymeric base material is made of woven fabrics, non-woven fabrics, films, hollow filament films (hollow fibes) or threads of polyolefinic material such as polyethylene, polypropylene or the like, and the reactive monomers are preferably vinyl reactive monomers or vinyl reactive monomers having chelate-forming groups.

Abstract: A process for producing a chitin derivative and/or a chitosan derivative that have a crosslinked structure, which comprises irradiating a paste of a mixture consisting of 100 parts by weight of a chitin derivative and/or a chitosan derivative and 3˜1,000 parts by weight of purified water.

Abstract: A process for producing a self-cross-linking alkyl cellulose derivative, which includes irradiating, with radioactive rays, a mixture of a starting alkyl cellulose derivative (the number of carbon atoms of the alkyl group is 1 through 3, the alkyl group may be substituted by a hydroxyl group or a carboxyl group, and the carboxyl group may form a salt) (100 parts by weight) and water (5-2,000 parts by weight), and thus obtained self-cross-linking alkyl cellulose derivative has an improved biodegradability and excellent water-absorbability.

Abstract: A paste of starch derivative is crosslinked by irradiation with &ggr;-rays or electron beams in a dose of 0.1-200 kGy. Two different levels of crosslinking are performed; the first is mild crosslinking by irradiation at a low dose of 0.1-1.0 kGy to such an extent that the viscosity of the overall system increases upon immersion in water, and the second is intensive crosslinking by irradiation at a higher dose than 1.0 kGy to produce a gel that is completely insoluble in water.

Abstract: A process for producing a chitin derivative and/or a chitosan derivative that have a crosslinked structure, which comprises irradiating a paste of a mixture consisting of 100 parts by weight of a chitin derivative and/or a chitosan derivative and 3˜1,000 parts by weight of purified water.

Abstract: The present invention relates to a polycaprolactone resin irradiated by ionizing radiation in order to adjust gel fraction to 0.01-90%, a polycaprolactone-contained resin composition containing at least any one of other biodegradable resins such as an aliphatic polyester resin and an additive for resins, and an molded article therefrom. The molded article includes a thin-walled molded article such as a film, a bag for garbages, a mulch film for agriculture, a shrink film, a sheet-like molded article, and a thick-walled vessel such as a blister pack, a tape, fiber materials such as fibers, woven fabrics, non-woven fabrics, and materials for filtration, a net, and a foam, etc.

Abstract: A process for producing a self-cross-linking alkyl cellulose derivative, which includes irradiating, with radioactive rays, a mixture of a starting alkyl cellulose derivative (the number of carbon atoms of the alkyl group is 1 through 3, the alkyl group may be substituted by a hydroxyl group or a carboxyl group, and the carboxyl group may form a salt) (100 parts by weight) and water (5-2,000 parts by weight), and thus obtained self-cross-linking alkyl cellulose derivative has an improved biodegradability and excellent water-absorbability.

Abstract: A paste of starch derivative is crosslinked by irradiation with y-rays or electron beams in a dose of 0.1-200 kGy. Two different levels of crosslinking are performed; the first is mild crosslinking by irradiation at a low dose of 0.1-1.0 kGy to such an extent that the viscosity of the overall system increases upon immersion in water, and the second is intensive crosslinking by irradiation at a higher dose than 1.0 kGy to produce a gel that is completely insoluble in water.

Abstract: Sodium alginate which is an oceanic natural resource is exposed, either in aqueous solution or in a dry state, to a radiation so that it is decomposed to a lower-molecular weight polysaccharide, which is processed into a dilute aqueous solution that is either used as a hydroponic solution or foliar spraying so as to promote their growth.

Abstract: The tear strength of a vulcanized natural rubber latex shaped article is improved by shaping a mixture of a prevulcanized natural rubber latex and a water-soluble polymer. The prevulcanization of a natural rubber latex may be done by exposure to a radiation. The water-soluble polymer may be selected from the group consisting of polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone and mixtures thereof. The water-soluble polymer may be added to the vulcanized natural rubber latex in an amount of 1-10 parts by weight per 100 parts by weight of the natural rubber.

Abstract: Polycaprolactone (PCL) is melted at a temperature of 60.degree. C. or higher and subsequently cooled down to a non-crystallizing temperature and exposed to radiation so that it is crosslinked and a network structure is introduced to impart heat resistance to the PCL. Because of the high degrees of its crosslinking, heat resistance and transparency, the PCL product can be used as a heat-resistant tape or a heat-shrinkable film.

Abstract: Disclosed are a PVA hydrogel which comprises being obtained by irradiating a polyvinyl alcohol aqueous solution containing a polymer selected from the group consisting of polyvinyl pyrrolidone, a methyl vinyl ether-maleic anhydride copolymer and an isobutylene-maleic anhydride copolymer, with ionizing radiations, a process for preparing the PVA hydrogel, a hydrogel laminate using the PVA hydrogel, a process for preparing the hydrogel laminate, and a hydrogel wound-dressing material using the PVA hydrogel.