Influence of temperature on accessible pyrolysis pathways of homopolymerized bisphenol A/F epoxies and copolymers

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Abstract

Understanding the thermal pyrolysis of epoxies and their copolymers is important for identifying structural changes resultant from thermal transients, enabling identification of failure modes of high-performance composite materials. This work expands our understanding of the thermal pyrolysis of cured epoxies and the role of temperature and composition on products, pathways, and relative rates. Numerous researchers have explored the pyrolysis of bisphenol A (BPA) epoxy. Significantly fewer have studied bisphenol F (BPF), and copolymers of BPA and BPF have been neglected. In this work, a pyrolysis gas chromatography mass spectrometer (PY-GC-MS) was used to investigate the degradation mechanism of homopolymerized BPA, BPF epoxies and their copolymers. For polymer identification, pyrolysis >450 °C resulted in the most extensive fragmentation and is useful for material identification, though lower temperatures show different degradation product profiles that provide mechanistic insight into thermal degradation pathways. Temperature greatly influences the accessible pyrolysis pathways of BPA, revealing dual mechanisms of formation for products p-isopropylphenol and p-isopropenylphenol. For BPF at low pyrolysis temperature the p,p-bisphenol F isomer is produced at significantly lower relative abundance compared to the abundance at higher temperatures tested, but production of the other two isomers changes little with respect to temperature. This suggests the epoxy components consisting of the p,p-bisphenol F isomer have higher thermal stability. Overall, the copolymer epoxies were found to have similar degradation products in stoichiometric distributions. The major exception was the formation of the p,p-bisphenol F isomer, which shows evidence of thermal stabilizing effects from addition of BPA epoxy.

Original languageEnglish
Article number104978
JournalJournal of Analytical and Applied Pyrolysis
Volume153
DOIs
StatePublished - Jan 2021

Funding

This research used resources from the Compute and Data Environment for Science (CADES) at Oak Ridge National Laboratory, which is supported by the US Department of Energy, Office of Science under Contract No. DE-AC05-00OR22725. The authors would like to thank Benjamin Kaercher, a summer intern who helped set up the instrument and methods used to perform this work as well as the internal reviewers at ORNL Michelle Kidder and Mark Arnould for their work in performing the preliminary reviews of this manuscript. Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). This research used resources from the Compute and Data Environment for Science (CADES) at Oak Ridge National Laboratory, which is supported by the US Department of Energy, Office of Scienceunder Contract No. DE-AC05-00OR22725. The authors would like to thank Benjamin Kaercher, a summer intern who helped set up the instrument and methods used to perform this work as well as the internal reviewers at ORNL Michelle Kidder and Mark Arnould for their work in performing the preliminary reviews of this manuscript.

FundersFunder number
Data Environment for Science
Office of Scienceunder
US Department of Energy
U.S. Department of Energy
Office of ScienceDE-AC05-00OR22725
Oak Ridge National Laboratory

    Keywords

    • Bisphenol A
    • Bisphenol F
    • Epoxy
    • Homopolymerized
    • Isomer
    • Pyrolysis-GC–MS

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