Cardanol and Eugenol Sourced Sustainable Non-halogen Flame Retardants for Enhanced Stability of Renewable Polybenzoxazines
Olefin bonds participate in co-reaction with the benzoxazine functionality of the monomer and are one of the strategies used to affect the crosslink density of a polybenzoxazine network. In general, the double bond incorporation in starting material is usually catalyzed by expensive, rare earth meta...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2020-09-01
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| Series: | Frontiers in Chemistry |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fchem.2020.00711/full |
| _version_ | 1811203557303517184 |
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| author | Divambal Appavoo Nagarjuna Amarnath Bimlesh Lochab |
| author_facet | Divambal Appavoo Nagarjuna Amarnath Bimlesh Lochab |
| author_sort | Divambal Appavoo |
| collection | DOAJ |
| description | Olefin bonds participate in co-reaction with the benzoxazine functionality of the monomer and are one of the strategies used to affect the crosslink density of a polybenzoxazine network. In general, the double bond incorporation in starting material is usually catalyzed by expensive, rare earth metals affecting the sustainability of the reaction. The natural abundance of feedstocks with inherent double bonds may be a powerful platform for the development of novel greener structures, with potential applications in polymers. Here, we report the design, synthesis, and characterization of a biobased non-halogen flame retardant, consisting of naturally occurring phenols, eugenol (E), and cardanol (C). The presence of a covalently linked phosphazene (P) core allowed the synthesis of hexa-functional flame retardant molecules, abbreviated as EP and CP. The chemical structures of the synthesized EP and CP were confirmed by Fourier transform infrared (FTIR), nuclear magnetic resonance (1H, 13C, 31P NMR), and single crystal XRD (only in the case of EP). Their polymerization with cardanol sourced tri-oxazine benzoxazine monomer, C-trisapm, was followed by FTIR, NMR, and DSC studies. The thermal stability and flame retardant properties of the hybrid phosphazene-benzoxazine copolymers was determined by thermogravimetry analysis (TGA), limiting oxygen index (LOI), vertical burning, and smoke density analyses. SEM images of the char residues of the polymers with or without the addition of reactive phosphazene molecules confirmed the intumescent flame retarding mechanism. Current work highlights the utility of sustainable origin non-halogen flame retardant (FR) molecules and their utility in polybenzoxazine chemistry. |
| first_indexed | 2024-04-12T02:57:24Z |
| format | Article |
| id | doaj.art-984484e072b44b67b9667da3447c3405 |
| institution | Directory Open Access Journal |
| issn | 2296-2646 |
| language | English |
| last_indexed | 2024-04-12T02:57:24Z |
| publishDate | 2020-09-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Chemistry |
| spelling | doaj.art-984484e072b44b67b9667da3447c34052022-12-22T03:50:45ZengFrontiers Media S.A.Frontiers in Chemistry2296-26462020-09-01810.3389/fchem.2020.00711551871Cardanol and Eugenol Sourced Sustainable Non-halogen Flame Retardants for Enhanced Stability of Renewable PolybenzoxazinesDivambal AppavooNagarjuna AmarnathBimlesh LochabOlefin bonds participate in co-reaction with the benzoxazine functionality of the monomer and are one of the strategies used to affect the crosslink density of a polybenzoxazine network. In general, the double bond incorporation in starting material is usually catalyzed by expensive, rare earth metals affecting the sustainability of the reaction. The natural abundance of feedstocks with inherent double bonds may be a powerful platform for the development of novel greener structures, with potential applications in polymers. Here, we report the design, synthesis, and characterization of a biobased non-halogen flame retardant, consisting of naturally occurring phenols, eugenol (E), and cardanol (C). The presence of a covalently linked phosphazene (P) core allowed the synthesis of hexa-functional flame retardant molecules, abbreviated as EP and CP. The chemical structures of the synthesized EP and CP were confirmed by Fourier transform infrared (FTIR), nuclear magnetic resonance (1H, 13C, 31P NMR), and single crystal XRD (only in the case of EP). Their polymerization with cardanol sourced tri-oxazine benzoxazine monomer, C-trisapm, was followed by FTIR, NMR, and DSC studies. The thermal stability and flame retardant properties of the hybrid phosphazene-benzoxazine copolymers was determined by thermogravimetry analysis (TGA), limiting oxygen index (LOI), vertical burning, and smoke density analyses. SEM images of the char residues of the polymers with or without the addition of reactive phosphazene molecules confirmed the intumescent flame retarding mechanism. Current work highlights the utility of sustainable origin non-halogen flame retardant (FR) molecules and their utility in polybenzoxazine chemistry.https://www.frontiersin.org/article/10.3389/fchem.2020.00711/fullcardanoleugenolphosphazeneflame retardanthalogen-freepolybenzoxazine |
| spellingShingle | Divambal Appavoo Nagarjuna Amarnath Bimlesh Lochab Cardanol and Eugenol Sourced Sustainable Non-halogen Flame Retardants for Enhanced Stability of Renewable Polybenzoxazines Frontiers in Chemistry cardanol eugenol phosphazene flame retardant halogen-free polybenzoxazine |
| title | Cardanol and Eugenol Sourced Sustainable Non-halogen Flame Retardants for Enhanced Stability of Renewable Polybenzoxazines |
| title_full | Cardanol and Eugenol Sourced Sustainable Non-halogen Flame Retardants for Enhanced Stability of Renewable Polybenzoxazines |
| title_fullStr | Cardanol and Eugenol Sourced Sustainable Non-halogen Flame Retardants for Enhanced Stability of Renewable Polybenzoxazines |
| title_full_unstemmed | Cardanol and Eugenol Sourced Sustainable Non-halogen Flame Retardants for Enhanced Stability of Renewable Polybenzoxazines |
| title_short | Cardanol and Eugenol Sourced Sustainable Non-halogen Flame Retardants for Enhanced Stability of Renewable Polybenzoxazines |
| title_sort | cardanol and eugenol sourced sustainable non halogen flame retardants for enhanced stability of renewable polybenzoxazines |
| topic | cardanol eugenol phosphazene flame retardant halogen-free polybenzoxazine |
| url | https://www.frontiersin.org/article/10.3389/fchem.2020.00711/full |
| work_keys_str_mv | AT divambalappavoo cardanolandeugenolsourcedsustainablenonhalogenflameretardantsforenhancedstabilityofrenewablepolybenzoxazines AT nagarjunaamarnath cardanolandeugenolsourcedsustainablenonhalogenflameretardantsforenhancedstabilityofrenewablepolybenzoxazines AT bimleshlochab cardanolandeugenolsourcedsustainablenonhalogenflameretardantsforenhancedstabilityofrenewablepolybenzoxazines |