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Synergistic effect of polyimide charring agent and hexaphenoxycyclotriphosphazene on improving fire safety of polycarbonate: High graphitization to strengthen the char layer
Author(s) -
Feng Haisheng,
Qian Lijun,
Lu Lingang
Publication year - 2021
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.5161
Subject(s) - charring , char , materials science , polycarbonate , fire retardant , polyimide , composite material , combustion , flammability , pyrolysis , layer (electronics) , fire performance , chemical engineering , organic chemistry , chemistry , fire resistance , engineering
To meet the increasingly stringent requirements for the excellent fire safety, low addition, low cost, and good mechanical properties for polycarbonate (PC), a novel aromatic polyimide (API) charring agent was synthesized and used synergistically with hexaphenoxycyclotriphosphazene (HPCTP) to flame‐retardant (FR) PC. The incorporated API and HPCTP improved FR performance and the fracture toughness of the PC, simultaneously. The 4H‐2A passed the UL94 V‐0 rating with a limited oxygen index of 32.5%. Moreover, the heat release rate of the PC was also suppressed significantly by the dense and strengthening carbon layer. The mechanism of synergistic charring effect of API and HPCTP were analyzed: In the initial and developing stages of combustion (below 450°C), the quenching effect and dilution effect of HPCTP played a major role in flame retardancy; and due to the barrier function of the highly graphitized char layer, the combustion process rapidly enters weakening stages (above 450°C) and finally extinguishes. Moreover, it was founded that API improved the antiimpact performance of PC matrix, which offsets the negative effect of HPCTP on the impact performance of PC matrix.