Open Access

ARTICLE

A New DOPO-Eugenol Adduct as an Effective Flame Retardant for Epoxy Thermosets with Improved Mechanical Properties

Daqin Zhang^1,2, Chufeng Yang³, Huayang Ran^1,2, 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, 710119, China
2 Engineering Research Center of Historical and Cultural Heritage Protection, Ministry of Education, Shaanxi Normal University, Xi’an, 710119, China
3 Hangzhou First Applied Material Co., Ltd., Hangzhou, 311300, China

* Corresponding Authors: Juanli Wang. Email: ; Jintao Wan. Email:

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

Journal of Renewable Materials 2022, 10(7), 1797-1811. https://doi.org/10.32604/jrm.2022.018754

Received 15 August 2021; Accepted 08 October 2021; Issue published 07 March 2022

Abstract

The development of efficient green flame retardants is an important way to realize more sustainable epoxy thermosets and downstream materials. In this work, a monoepoxide is synthesized through O-glycidylation of eugenol, and then reacted with DOPO (9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide) to obtain a new bio-based flame retardant, DOPO-GE. DOPO-GE is blended with a bisphenol A epoxy prepolymer exhibiting good compatibility and DDS (4,4′-diaminodiphenylsulfone) is used as the curing agent to afford epoxy thermosets. Although DOPO-GE leads to the reduced glass transition temperature of the thermosets, the storage modulus increases considerably. The DOPO-GE-modified thermosets exhibit the high thermal stability with the onset thermal decomposition temperature in nitrogen and air exceeding 300°C. When the phosphorus content in the thermoset is 1.0%, the residual yield of the thermosets at 750°C in nitrogen increases from 13.9% to 30.6%, due to the increased charring ability. More interestingly, when the phosphorus content is only 0.5%, the limiting oxygen index is as high as 30.3% with UL94 V0 achieved. Cone calorimeter results reveals the signifi- cantly decreased heat release rate, total heat release, mass loss and total smoke production. Furthermore, DOPO-GE can notably improve the flexural strength, flexural modulus and fracture toughness, whereas the shear and impact strength are reduced to varied extents. In short, DOPO-GE can be obtained via a facile way, and shows the good flame-retardant effect on the epoxy thermosets with an application potential.

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