Radiation-induced crosslinking of polyamide11 in presence of triallyl isocyanulate

Nagasawa, Naotsugu; Tago, Takanori*; Kudo, Hisaaki*; Tamada, Masao; Katsumura, Yosuke; Taguchi, Mitsumasa

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.