RESUMO
In this study, a nematic phase structure is incorporated into polybenzoxazine to increase its thermal conductivity. A simple route for the synthesis of a thermally conductive polybenzoxazine containing liquid crystalline (LC) structure by grafting oligomeric p-sulfophenylene-terephthalamide (PSTA) is offered. Benzoxazine monomer of pHBA-da is synthesized via Mannich reaction of p-hydroxy benzoic acid, p-formaldehyde, and dodecyl amine. After ring-opening polymerization, the oligomer benzoxazine of OBZâCOOH is obtained. The OBZâCOOH/PSTA mixture is prepared by mixing PSTA with OBZâCOOH. Afterward, the grafted copolymer is named OBZâPSTA copolymer. The liquid crystalline behavior of OBZâCOOH/PSTA is studied by polarized optical microscopy and small angle X-ray scattering analysis. The results show that the OBZâPSTA forms the LC structure during isothermal and non-isothermal curing. The LC structure displays a floral textured nematic phase. The phase formation is induced by an amidation reaction. Due to the grafts of LC PSTA, the thermal conductivity of OBZâPSTA is 0.296 W m-1 K-1 , which is 26% greater than OBZâCOOH. The glass transition temperature (Tg ) of OBZâPSTA is 241 °C. The 5% (Td5 ) and 10% weight loss temperatures (Td10 ) of OBZâPSTA are 346 and 362 °C, respectively.