Lab of Polymer Material and Engineering, Ningbo Institute of Technology, Zhejiang University, Ningbo, Zhejiang 315100, China
b
Ningbo Key Laboratory of Polymer Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences Institution, Ningbo, Zhejiang 315201, China
c
Centre of Excellence in Engineered Fibre Composites (CEEFC), University of Southern Queensland, Toowoomba, Queensland 4350, Australia
Highlights
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An intrinsically flame retardant bio-based benzoxazine (DPA-PEPA-boz) was synthesized from renewable diphenolic acid.
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The residual char of P-DPA-PEPA-boz after 400 °C was much higher than those of P-DPA-boz and P-MDP-boz under nitrogen and air atmospheres.
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P-DPA-PEPA-boz had a limiting oxygen index (LOI) of 33.5% and achieved V0 level in UL94 test.
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Thus, this study demonstrates the great potentials of the intrinsically flame retardant bio-based benzoxazine (DPA-PEPA-boz) in the application of high performance matrix resin and composite material.
Abstract
An intrinsically flame retardant bio-based benzoxazine (diphenolic acid pentaerythritol caged phosphate benzoxazine, DPA-PEPA-Boz) monomer was synthesized from bio-based diphenolic acid (DPA) using a four-step process. The monomer of DPA-PEPA-Boz was characterized by FT-IR, 1H NMR and 13C NMR. The curing behavior of DPA-PEPA-boz was studied and compared with those of DPA based benzoxazine (DPA-Boz) and DPA ester derivative (MDP) based benzoxazine (MDP-Boz) without PEPA by means of non-isothermal differential scanning calorimetry. The results indicated that DPA-PEPA-Boz system showed a two-stage curing, assigned to the exothermic opening reactions of oxazine rings and P–O–C ring in PEPA respectively, while the DPA-Boz and MDP-Boz showed a one-stage curing. In addition, the effect of the introduction of PEPA on thermal and inflammable properties of the resin was evaluated. The residual char of the cured DPA-PEPA-Boz (P-DPA-PEPA-Boz) after 400 °C was much higher than those of cured DPA-Boz (P-DPA-Boz) and cured MDP-Boz (P-MDP-Boz) under nitrogen and air atmospheres. Meanwhile, total heat release (THR), peak heat release rate (PHRR) and heat release capacity (HRC) of P-DPA-PEPA-Boz were about half of those of P-DPA-Boz and P-MDP-Boz. P-DPA-PEPA-Boz had a limiting oxygen index (LOI) of 33.5% and achieved V0 rating in UL94 test. P-DPA-PEPA-Boz behaved as a very good intrinsic thermal and flame retardant bio-based benoxazine resin.
Graphical abstract
An intrinsically flame retardant bio-based benzoxazine (DPA-PEPA-boz) has been synthesized and behaved as a very good intrinsic thermal stable and flame retardant bio-based benzoxazine resin.
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