Abstract
This work explores the strategy of incorporating a highly substituted reactive flame retardant into a benzoxazine moiety. For this purpose, a DOPO-based flame retardant received a chain extension via reaction with ethylene carbonate. It was then reacted with phloretic acid to obtain a diphenol end-capped molecule, and further reacted with furfurylamine and paraformaldehyde to obtain a benzoxazine monomer via a Mannich-like ring closure reaction. This four-step synthesis yielded a partly bio-based halogen-free flame retardant benzoxazine monomer (DOPO-PA-fa). The successful synthesis was proven via NMR, IR and MS analysis. The polymerization behavior was monitored by DSC and rheological analysis both showing the polymerization starts at 200 °C to yield pDOPO-PA-fa. pDOPO-PA-fa has a significant thermal stability with a residual mass of 30% at 800 °C under ambient atmosphere. Furthermore, it reached a V-0 rating against small flames and an OI of 35%. Blended with other benzoxazines, it significantly improves their thermal stability and fire resistance. It emphasizes its potential as flame retardant agent.
Highlights
The structural features of DOPO-phloretic acid (PA) were determined by 1 H NMR, FTIR and Mass spectrometry (MS). 1 H NMR spectrum of DOPO-PA proved the full conversion of DOPOOH as attested by the disappearance of the aliphatic hydroxyl groups at 4.46 ppm and
This study describes the incorporation of a DOPO spacer group into bio-based benzoxazine monomer
DOPO-HQ was reacted with ethylene carbonate to promote its reactivity toward a solvent-free esterification with PA, to obtain a diphenol end-capped DOPO
Summary
Polybenzoxazines are thermosetting materials with excellent properties, such as a near-zero shrinkage upon polymerization [1], high mechanical and thermal properties [2]. They have gained a lot of attention during the last decade since many different bio-sourced synthons can be used to design their molecular structure, which require a primary amine, a phenol non-substituted in ortho position and an aldehyde. Vanilin [8] have been employed as amines; guaiacol [4,9], sesamol [10,11], cardanol [7,12,13], eugenol [14] or phloretic acid (PA) [15,16] have been used as naturally occurring phenolic compounds. The design of formaldehyde-free monomers is hyping, with the recent works of Caillol et al [17,18], and Ishida and Froimowicz et al [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
