|
Development of the environment-friendly elastic gels derived from the plant-resources.Dec. 7, 2006The Japan Atomic Energy Agency (hereafter JAEA, President Yuichi Tonozuka) in collaboration with Gunma Industry Support Organization (hereafter GISO, President, Tomihiko Tomita) (since 2006 FY) developed a novel biodegradable gel having rubber-like properties by means of radiation-induced crosslinking and acid treatment of carboxymethylcellulose (hereafter CMC). This study has been done by Dr. Masao Tamada, Mr. Toshiaki Yagi, Dr. Naotsugu Nagasawa (JAEA), Dr. Machiko Takigami, Ms. Haruyo Amada (GISO) and colleagues under Gunma Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence (Representative researcher, Gunma Industrial Technology Center, Senior Director Yutaka Uematsu), Japan Science and Technology Agency. Considering the problems of global warming and depletion of finite resources, it is an ideal to use the plant-resource products that are biodegradable instead of the materials synthesized from petroleum resources. JAEA recently has developed the biodegradable gel formed by radiation-induced crosslinking technology of polysaccharide derivatives such as CMC, carboxymethyl starch, carboxymethyl chitin / chitosan etc in aqueous paste at concentration more than 10%. Though the obtained polysaccharide gels have an excellent water-absorbing property (contain more than 400 times water / 1 gram dry gel), the gels is so fragile and/or brittle in the swollen state. Therefore, the radiation crosslinked polysaccharide gels were limited to application fields utilizing their higher water-absorbing property. In this collaborative research, we developed a novel biodegradable CMC gel having rubber-like characteristic by means of two techniques the radiation-induced crosslinking and acid treatment. The gels with different elasticity and hardness were prepared via changing the degree of substitution of CMC, weight average molar weight of CMC, types of acid and concentrations of acid and CMC. The novel gels were able to keep the strength even in the swollen state contained 10 ~ 100 times water. For example, strength of the CMC gel obtained by 20kGy gamma-irradiation in 20% CMC paste with acid treatment of 1 mole HCl aqueous solution was 150 times (3N/mm2) higher than that obtained with only radiation-induced crosslinking treatment. It is expected that the elastic gels can be used in wide application fields, such as the pastoral (the livestock excrement processing materials), in the cosmetic (the packing materials), and in the medical (the base material of slow-release drug systems) etc. Those results were presented in the 17th MRS-J academic symposium on December 10, 2006 in Tokyo. |
