Open Access

ARTICLE

A Vanillin-Derived, DOPO-Contained Bisphenol as a Reactive Flame Retardant for High-Performance Epoxy Thermosets

by Li Wang^1,2,#, Rongbai Tong^3,#, Juanli Wang^1,2,*, Jintao Wan^1,2,*, Yuhu Li^1,2, Pujun Jin^1,2, Daodao Hu^1,2

1 School of Materials Science and Engineering, Shaanxi Normal University, Xi’an, 710062, China
2 Engineering Research Center of Historical and Cultural Heritage Protection, Ministry of Education, Shaanxi Normal University, Xi’an, 710062, China
3 Hangzhou First Applied Material Co., Ltd., Hangzhou, 311300, China

* Corresponding Authors: Juanli Wang. Email: ," />; Jintao Wan. Email: " />
# The authors contribute equally

(This article belongs to the Special Issue: Bio-based Halogen-free Flame Retardant Polymeric Materials)

Journal of Renewable Materials 2022, 10(5), 1349-1364. https://doi.org/10.32604/jrm.2022.019372

Received 20 September 2021; Accepted 22 October 2021; Issue published 22 December 2021

Abstract

Quest for bio-based halogen-free green flame retardant has attracted many concerns in recent years. Herein a reactive functional flame retardant containing phosphorus VDP is synthesized from vanillin, 9,10-dihydro-9-oxa-10-phosphophene-10-oxide (DOPO) and phenol via a facile way. VDP is characterized with ¹H NMR, ³¹P NMR, FTIR and Time of Flight Mass Spectrometry, and used as a new reactive flame retardant for bisphenol epoxy thermosets. Thermogravimetry analysis shows that when the VDP loading is only 0.5P% (based on phosphorus content), the residue increases from 14.2% to 21.1% at 750°C in N₂ compare with neat DGEBA. Correspondingly, the limit oxygen index increased to 29.6%, and flame retardancy reaches UL-94 V0 grade. Micro combustion calorimetry (MCC) and cone calorimetry analyses demonstrate that VDP can significantly lower flammability of the epoxy thermoset. With only 0.5P% of VDP, the heat release rate, total heat release rate and smoke production are reduced markedly. At the same time, the mechanical properties of the modified epoxy thermosets are also improved. The impact strength increases by 34% and the flexural strength increased by 23%, with 1.5P% of VDP. In short, VDP not only improves the flame retardancy, but also improves the mechanical properties of the epoxy thermosets.

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