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Nagasawa, Naotsugu; Tago, Takanori*; Kudo, Hisaaki*; Tamada, Masao; Katsumura, Yosuke; Taguchi, Mitsumasa
no journal, ,
Polyamide11, (PA11) or Nylon 11 is one of polyamide bioplastics derived from castor beans oil. PA11 has excellent properties such as superior thermal resistance, chemical resistance, good flexibility and good impact resistance. Radiation-induced crosslinking is an effective method to improve the thermal stability of polymers. It was found that poly(L-lactic acid) (PLLA) which is other bioplatic derived from renewable resources such as sugar or corn starch, has improved the heat resistance property by radiation-induced crosslinking with triallyl isocyanurate (TAIC). PA11 is a most promising candidate for blending material of PLLA to improve the brittleness and lack of flexibility of the PLLA. In this study, to improve the above-mentioned two properties of PLLA, we investigated radiation-induced crosslinking of PA11 with TAIC in order to obtain a basic knowledge about production of blend material of PLLA and PA11. The crosslinking structures were formed in irradiated PA11 without and with TAIC. The gel content of PA11 increased with the absorbed dose and additive concentration of TAIC. The gel fraction of PA11 without TAIC is about 9.7% at irradiation dose of 200 kGy, 39.9% at 300 kGy, 60.3% at 500 kGy, respectively, and saturated to 76.2% at even higher than 750 kGy. Although no gelation was observed below 190 kGy. For TAIC added PA11, the gel content increased significantly at the lower dose of 200 kGy. The network was formed about 85% in 3 phr (per hundred resin) TAIC added PA11 samples at the dose of 10 kGy. The thermal properties of the samples were evaluated from the deformation at the Tm evaluated by the thermo-mechanical analysis. The TAIC added PA11 with high gel contents (
80%) by irradiation demonstrated very little deformation above the Tm of PA11 around 185 
C. Therefore, the applications of bioplastic will be expected expanding by the radiation-induced crosslinking.
Nagasawa, Naotsugu; Kanazawa, Shinichi*; Yoshii, Fumio; Tamada, Masao; Taguchi, Mitsumasa
no journal, ,
Poly(L-lactic acid) (PLLA) is one of bioplastics as the most attractive materials because it is a most promising candidate for replacement of petrochemical plastics in viewpoint of global protection. Radiation-induced crosslinking of PLLA with triallyl isocyanurate (TAIC) has been improved the heat resistance property in previous study. The applications of crosslinked PLLA, however, are limited, because the lack of flexibility is nearly un-improved. The plasticizer exude from PLLA because of recrystallization at room temperature, and the PLLA becomes hard consequentry with cloudiness. To solve the problem and expand the further applications of PLLA, effect of additive plasticizer on radiation-crosslinking PLLA with TAIC and retention capacity in crosslinked PLLA were investigated. The crosslinking structures were formed in electron beam-irradiated PLLA with 3 phr TAIC and various content of plasticizer. The gel content of PLLA increased with the mixing ratio of the plasticizer and absorbed dose. At the dose of 20 kGy and more, the network was formed about 90% in the crosslinked PLLA. The plasticizer didn't exude from the crosslinked PLLA even if heated for one week at 80 C because of non-recrystallization, and so the crosslinked PLLA kept transparency. Improvement of elasticity was succeeded by adding high concentrated plasticizer ( 35%) in PLLA. Therefore, the applications of bioplastic will be expanded by the combination method of the radiation-induced crosslinking and adding high content of plasticizer.
Maekawa, Yasunari; Yoshimura, Kimio; Koshikawa, Hiroshi; Yamaki, Tetsuya; Yamamoto, Kazuya*; Shishitani, Hideyuki*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*
no journal, ,
Anion-exchange membranes (AEM) for hydrazine fuel cells, in which non precious metals are used as an electrode catalyst, have been developing by radiation techniques. AEMs having polyvinylimidazolium grafts were synthesized by radiation-induced graft polymerization of N-vinylimidazole or the copolymerizaiton with styrene onto ETFE film, followed by N-alkylation and ion exchange reactions. The alkaline durability of the membranes was evaluated in 1M KOH at 80 C. The AEM consisting of the homopolymer grafts showed alkaline stability at 80 C for ca. 150 hours. In contrast, the copolymer (1:1 molar ratio) grafts type AEM kept its ion conductivity above 10 mS/cm in 1M KOH at 80 C for 250 h. The alkylimidazolium group in the copolymer grafts is a promising anion exchange group in AEMs for highly alkaline durable fuel cells.