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In this study, the curing behavior of polycardanol containing epoxy groups (diepoxidized polycardanol) was exploited in terms of thermal stability and the cure reaction conversion by means of thermogravimetric analysis and Fourier-transform infrared spectroscopy, respectively. The effect of photo-initiator type and concentration and electron beam absorption dose in the presence of cationic photo-initiators (triarylsulfonium hexafluorophosphate (P-type) and triarylsulfonium hexafluoroantimanate (Sb-type) on the cure behavior of diepoxidized cardanol (DEC) resin was investigated. The thermal stability of DEC with Sb-type photo-initiator was higher than that with P-type one, being increased with increasing the concentration and electron beam absorption dose. The conversion of cure reaction was gradually increased with increasing the dose, showing the maximum at 800 kGy. The results revealed that Sb-type photo-initiator, the concentration of 2 or 3 wt %, and electron beam absorption dose of about 800 kGy may be preferable for initiating epoxy ring opening in the DEC molecules as well as for efficiently curing the DEC resin by electron beam irradiation. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41599.

In this study, the glass transition, thermal expansion, dynamic mechanical properties, and water-uptake behaviors of diepoxidized polycardanol (DEPC) cured by electron-beam radiation in the presence of cationic photoinitiators were investigated. How the type and concentration of cationic photoinitiators and the electron-beam absorption dose influenced the properties of the cured DEPC was also studied. Two types of cationic photoinitiators, triarylsulfonium hexafluorophosphate (simply referred to as phosphate type or P-type) and triarylsulfonium hexafluoroantimonate (simply referred to as antimonate type or Sb-type), were used. Electronbeam absorption doses of 200, 300, 400, and 600 kGy were applied to the uncured diepoxidized cardanol (DEC) samples, respectively. It was revealed that the Sb-type photoinitiator was preferable to the electron-beam curing of DEC; this led to a lower photoinitiator concentration and/or a lower electron-beam absorption dose compared to that in the phosphate-type photoinitiator. As a result, the variations in the glass-transition temperature, coefficient of thermal expansion, storage modulus, and water uptake of the cured DEPC were quite consistent with each other. We found that the optimal conditions for the enhanced properties of DEPC by electron-beam curing were an Sb-type photoinitiator at 2 wt % and an electron-beam absorption dose of 600 kGy. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42570.