Exploring Structure-Property Relationships in Aromatic Polybenzoxazines Through Molecular Simulation

A series of commercial difunctional benzoxazine monomers are characterized using thermal and thermo-mechanical techniques before constructing representative polymer networks using molecular simulation techniques. Good agreement is obtained between replicate analyses and for the kinetic parameters obtained from differential scanning calorimetry data (and determined using the methods of Kissinger and Ozawa). Activation energies range from 85 to 108 kJ/mol (Kissinger) and 89 to 110 kJ/mol (Ozawa) for the uncatalyzed thermal polymerization reactions, which achieve conversions of between 85% and 97%. Glass transition temperatures determined from differential scanning calorimetry and dynamic mechanical thermal analysis are comparable, ranging from BA-a (151 degrees C, crosslink density 3.6 x 10(-3) mol cm(-3)) containing the bisphenol A moiety to BP-a, based on a phenolphthalein bridge (239 to 256 degrees C, crosslink density 5.5 to 18.4 x 10(-3) mol cm(-3), depending on formulation). Molecular dynamics simulations of the polybenzoxazines generally agree well with empirical data, indicating that representative networks have been modelled.