Abstract
The possibility of a novel high heat-resistant thermosetting resin was investigated, with the reaction of a phenolic hydroxyl group generated by ring opening polymerization of benzoxazine with an epoxy group. First of all, 3,3′-(methylene-1,4-diphenylene) bis (3,4-dihydro-2H-1,3-benzoxazine) (P-d type benzoxazine) was selected for its thermal properties. Using P-d type benzoxazine and bisphenol-A-based epoxy resin (DGEBA), epoxy resins modified polybenzoxazines were prepared. The thermal stabilities were improved remarkably and the thermoplastic property of polybenzoxazine to soften at temperatures of more than 200°C was improved. In addition, an improvement of the thermal properties by reducing equivalent ratio of epoxy group to hydroxyl group of phenol was confirmed. PdBA (0.3), whose ratio of epoxy group to hydroxyl group was 0.3, showed a Tg of 206°C and a CTE of 47 ppm/K. In addition, by using a liquid crystal type epoxy resin or a polyaromatic type epoxy resin instead of DGEBA, further improvement of the thermal and mechanical properties was suggested. Moreover, by the addition of BF3 (NH2Et), the curing reaction was accelerated, maintaining the thermal properties of the cured resins.
