ma401444z_si_001.pdf (1.3 MB)
New Method To Predict the Thermal Degradation Behavior of Polybenzoxazines from Empirical Data Using Structure Property Relationships
journal contribution
posted on 2013-10-08, 00:00 authored by Ian Hamerton, Scott Thompson, Brendan
J. Howlin, Corinne A. StoneThe
degradation behavior of five polybenzoxazines is studied and the effect
of selected experimental parameters (particle size, heating rate,
and atmosphere) on the nature of the degradation pathway is examined.
The particle size within the samples (systematically varied in four
discrete size ranges: <106, 106–150, 150–250, >250
μm) influences the progress of the early stage in the degradation
mechanism (the cleavage of the bridging groups) such that the smaller
particles are less stable, but the latter stages of the degradation
mechanism remain largely unaffected. In contrast, the change in heating
rate (5, 10, 15, 20 K min–1) of the thermogravimetric
analysis has little effect on the first step in the degradation mechanism,
but has a strong influence on the progress of the ring breakdown mechanism.
Molecular simulation is shown to reproduce the thermo-mechanical behavior
of the polybenzoxazine of bisphenol A/aniline very well, with the
nuances of the glass transition and degradation onset temperatures
simulated very closely (e.g., within 10 °C of the degradation
experiment at a mass loss of 5 wt %). Quantitative structure property
relationships are shown to predict the experimental char yields for
all the polybenzoxazines studied within the data set, with the calculated
values for the polymers based solely on the volume and surface area
of the monomer structures.