Bio-based epoxy networks incorporating covalent and melamine cyanurate-type multiple hydrogen-bonding crosslinkages

Prepolymerizations of polyglycidyl ether of polyglycerol (PGPE) with equimolar amounts of melamine (ML) and isocyanuric acid (iCA) at 80 °C and subsequent compression molding at 130–190 °C yielded cured PGPE/ML/iCA resins with epoxy/active hydrogen ratios of 1/3, 2/3 and 3/3 (PGPE-MC13, 23 and 33). Their properties were compared with the PGPE cured with ML or iCA with an epoxy/active hydrogen ratio of 1/1 (PGPE-ML or PGPE-iCA). Transparency of the cured resins became worse with increasing multiple hydrogen-bonding melamine cyanurate (MC = ML + iCA) fraction. The FT-IR analysis revealed that the epoxy groups were almost consumed for all of the cured resins, and the hydrogen bonding interaction became stronger with increasing MC fraction. Although glass transition temperatures ( T g s) of PGPE-MCs were a little lower than those of PGPE-ML and PGPE-iCA, the T g increased with MC fraction. The 5 % weight loss temperatures of PGPE-MCs were much higher than those of PGPE-ML and PGPE-iCA. The flexural modulus for PGPE-MCs increased with increasing MC fraction, and PGPE-MC13 exhibited the highest flexural modulus among all of the cured resins.