Examining the thermal behaviour of novel aromatic polybenzoxazine blends containing an organophosphorous compound and polyhedral oligomeric silsesquioxane reagents

Abstract

Abstract2,2‐Bis(3,4‐dihydro‐3‐phenyl‐2H‐1,3‐benzoxazine)propane (BA‐a) is blended with various commercial polyhedral oligomeric silsesquioxane (POSS) reagents and an organophosphorous compound, bis(4‐hydroxyphenyl)phenylphosphine oxide (BPPO), at a range of loadings (1–10 wt%). The influence of the additives on the onset and rate of polymerisation of BA‐a is examined using differential scanning calorimetry. An initial screen of blends containing various additives (5 wt%) shows that a combination of aminoethylaminopropyl isobutyl POSS (AEAP) and BPPO has the greatest effect on reactivity with a reduction in reaction onset of some 65 K and an increase in glass transition temperature of 18 K when compared with the BA‐a homopolymer. The activation energy for the polymerisation of BA‐a containing 5 wt% AEAP is determined to be 84–88 kJ mol−1 (using Kissinger and Ozawa kinetic models), with a first‐order rate constant of 1.9 × 108 s−1. The thermal stability of the cured blends containing 5 wt% flame retardant is examined using thermogravimetric analysis, and both onset of degradation and char yield are increased by 15 K and 5%, respectively, when compared with the BA‐a homopolymer. © 2016 Society of Chemical Industry