Polymer, Vol.88, 52-62, 2016
Examining the influence of bisphenol A on the polymerisation and network properties of an aromatic benzoxazine
A series of reactive blends, comprising a commercial benzoxazine monomer, 2,2-bis(3,4-dihydro-3phenyl- 2H-1,3-benzoxazine) propane, and bisphenol A is prepared and characterized. Thermal analysis and dynamic rheology reveal how the introduction of up to 15 wt % bisphenol A lead to a significant increase in reactivity (the exothermic peak maximum of thermal polymerization is reduced from 245 degrees C to 215 degrees C), with a small penalty in glass transition temperature (reduction of 15 K), but similar thermal stability (onset of degradation = 283 degrees C, char yield = 26%). With higher concentrations of bisphenol A (e.g. 25 wt %), a significantly more reactive blend is produced (exothermic peak maximum = 192 degrees C), but with a significantly lower thermal stability (onset of degradation = 265 degrees C, char yield = 22%) and glass transition temperature (128 degrees C). Attempts to produce a cured plaque containing 35 wt % bisphenol A were unsuccessful, due to brittleness. Molecular modelling is used to replicate successfully the glass transition temperatures (measured using thermal analysis) of a range of copolymers. (C) 2016 Elsevier Ltd. All rights reserved.