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Licensed Unlicensed Requires Authentication Published by De Gruyter May 14, 2021

Synthesis of a Flame Retardant for Epoxy Resins: Thermal Stability, Flame Retardancy, and Flame-Retardant Modes

Y. Zhang, J. Liu and S. Li

Abstract

A polyphosphonate (PDPA) flame retardant that contains phenyl phosphonic dichloride and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide groups, has been synthesized. The flame retardant was introduced into epoxy resins (EP) and cured by 4,4’-diamino diphenylmethane. The vertical burning, limited-oxygen index and cone calorimeter tests reveal that the PDPA can enhance the flame-retardant properties of the EP significantly. With only a 4 wt% PDPA loading, the EP composites achieved a limited-oxygen index value of 33.4% and a V-0 rating in the vertical burning test, and the peak heat release rate and total heat release were decreased by 40.9% and 24.6%, respectively. The thermal properties and gas pyrolysis products of the EP composites were evaluated by thermogravimetric analysis and thermogravimetric analysis-Fourier transform infrared spectroscopy, and the morphology and structure of residual char were characterized by scanning electron microscopy, Flourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. To explain the combined effects of the condensed and gas phases, modes of the flame-retardant action are proposed.


* Mail address: Yi Zhang, School of Biology and Chemical Engineering, Shandong Vocational College of Science & Technology, Weifang 261053, PRC


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Received: 2019-11-13
Accepted: 2020-10-01
Published Online: 2021-05-14
Published in Print: 2021-05-26

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