Investigation of polymerization of benzoxazines and thermal degradation characteristics of polybenzoxazines via direct pyrolysis mass spectrometry

Abstract

Polymerization of benzoxazines and thermal degradation mechanisms of polybenzoxazines were investigated using the direct pyrolysis mass spectrometry (DP-MS) technique. The benzoxazine structures were based on phenol and aniline and on bisphenol-A and methylamine or aniline. Polymerizations of the benzoxazines were carried out by curing them at elevated temperatures without addition of initiator or catalyst. DP-MS data showed the presence of chains generated by opposing polymerization reaction pathways indicating quite complex structures for the polybenzoxazines under investigation. Thermal decomposition of polybenzoxazines was started by the cleavage of methylamine or aniline linkages. It was determined that polybenzoxazines based on phenol were more stable than the corresponding bisphenol-A-based polybenzoxazines, while those based on methylamine were more stable than the corresponding polybenzoxazines incorporating aniline. Thus, it can be concluded that the presence of bulky groups decreased the extent of crosslinking which in return decreased the thermal stability. © 2012 Society of Chemical Industry

Renewable benzoxazine monomers from “lignin-like” naturally occurring phenolic derivatives

“…Most benzoxazine monomers reported in the literature are stable at the polymerization temperature 150–250 °C allowing preparing well defined thermosetting resins. At higher temperatures polybenzoxazine resins undergo well known thermal degradation processes, which have been the matter of several studies . The unsaturated monomers studied in this work show an unusual low thermal stability, which must be related with some structural characteristics.…”

High performance benzoxazine/CNT nanohybrid network – An easy and scalable way to combine attractive properties

“…The degradation mechanism is not yet well clarified but is probably correlated with the evolution of a Zwiterionic intermediate. An equilibrium between two species is set during the polymerization, the first favoring polymerization while the second leading to the dissociation of the aminophenyl moiety and the subsequent release of a volatile imine [17,18,37,38]. In the case of P-pPDA, the aminophenyl moiety is trapped into two benzoxazine rings limiting its cleavage during the network forming.…”

High‐Performance Bio‐Based Benzoxazines from Enzymatic Synthesis of Diphenols

“…This result is due to the high content of aromaticity linked to phenolic and furan groups within the structure of the resulting cross‐linked materials. Indeed, furan is known to further increase the cross‐linking density of the cured polybenzoxazines and suppress segmental decomposition into gaseous fragments as the decomposition of polybenzoxazines is usually considered to begin with the cleavage of the amino part . It is worth noting that such a high charring ability is of high interest for the preparation of more sustainable light‐weight structural composite materials for application in transport industries (railway, aeronautic, aerospace for instance…) where high performance represent a prerequisite.…”