This study presents the development of a bio-based flame retardant derived from renewable soybean oil to improve the flame retardant performance of poly (lactic acid) (PLA). Soybean oil phosphate ester (SOPE) was synthesized from epoxidized soybean oil (ESO) and incorporated into PLA at loadings of 0.5–2 phr via twin-screw extrusion. FT-IR and NMR analyses confirmed the successful synthesis of SOPE. Thermal analysis revealed that the incorporation of SOPE influenced the thermal degradation behavior and crystallization properties of PLA. PLA containing 2 phr SOPE achieved a limiting oxygen index (LOI) value of 26% and attained a V-0 rating in the UL-94 vertical burning test, indicating effective flame retardancy at a low loading level. TGA results showed a relatively low char yield, suggesting that the flame retardant mechanism did not predominantly occur in the condensed phase. Py-GC/MS analysis detected phosphorus-containing radical species (PO• and PO2•), indicating that the flame retardant action mainly proceeded via a gas-phase radical trapping mechanism. However, the incorporation of SOPE led to a reduction in molecular weight and mechanical properties due to the hydrolytic degradation of PLA. Overall, the results demonstrate that soybean oil–derived phosphate ester can serve as a bio-based and effective flame retardant for PLA.
SreekumarKBindhuBVelurajaK. Perspectives of polylactic acid from structure to applications. Polym Renew Resour2021; 12(1-2): 60–74. https://doi.org/10.1177/20412479211008773
4.
GhasemlouMBarrowCJAdhikariB. The future of bioplastics in food packaging: an industrial perspective. Food Packag Shelf Life2024; 43: 101279. https://doi.org/10.1016/j.fpsl.2024.101279
MandalMRoyAMitraD, et al.Possibilities and prospects of bioplastics production from agri-waste using bacterial communities: finding a silver-lining in waste management. Curr Res Microb Sci2024; 7: 100274. https://doi.org/10.1016/j.crmicr.2024.100274
7.
MerinoDSimonuttiRPerottoG, et al.Direct transformation of industrial vegetable waste into bioplastic composites intended for agricultural mulch films. Green Chem2021; 23(16): 5956–5971. https://doi.org/10.1039/d1gc01316e
8.
CampanaleCGalafassiSDi PippoF, et al.A critical review of biodegradable plastic mulch films in agriculture: definitions, scientific background and potential impacts. TrAC, Trends Anal Chem2024; 170: 117391. https://doi.org/10.1016/j.trac.2023.117391
9.
BozóÉErvastiHHalonenN, et al.Bioplastics and carbon-based sustainable materials, components, and devices: toward green electronics. ACS Appl Mater Interfaces2021; 13(41): 49301–49312. https://doi.org/10.1021/acsami.1c13787
CarvalhoDFerreiraNFrançaB, et al.Advancing sustainability in the automotive industry: bioprepregs and fully bio-based composites. Composer, Part C: Open Access2024; 14: 100459. https://doi.org/10.1016/j.jcomc.2024.100459
12.
VieyraHMolina-RomeroJMCalderón-NájeraJD, et al.Engineering, recyclable, and biodegradable plastics in the automotive industry: a review. Polymers2022; 14(16): 1–18. https://doi.org/10.3390/polym14163412
13.
KhankruaRWiriya-AmornchaiATriamnakN, et al.Biopolymer blends based on poly(lactic acid) and polyamide for durable applications. Polym-Plast Technol Mater2023; 62(2): 131–144. https://doi.org/10.1080/25740881.2022.2096470
LaoutidFBonnaudLAlexandreM, et al.New prospects in flame retardant polymer materials: from fundamentals to nanocomposites. Mater Sci Eng Report2009; 63(3): 100–125. https://doi.org/10.1016/j.mser.2008.09.002
16.
CostesLLaoutidFBrohezS, et al.Bio-based flame retardants: when nature meets fire protection. Mater Sci Eng Report2017; 117: 1–25. https://doi.org/10.1016/j.mser.2017.04.001
17.
MorganABGilmanJW. An overview of flame retardancy of polymeric materials: application, technology, and future directions. Fire Mater2013; 37(4): 259–279. https://doi.org/10.1002/fam.2128
18.
AbnikiMRahmaniZSoleimani-GorganiA, et al.Recent advances in green flame retardant compounds for application in polymers: a review. Polym Renew Resour2025; 16(4): 209–243. https://doi.org/10.1177/20412479251345678
19.
CarvalhoBOGonçalvesLPCMendonçaPV, et al.Replacing harmful flame retardants with biodegradable starch-based materials in polyethylene formulations. Polymers2023; 15(20): 4078. https://doi.org/10.3390/polym15204078
20.
XiaYChaiWLiuY, et al.Facile fabrication of starch-based, synergistic intumescent and halogen-free flame retardant strategy with expandable graphite in enhancing the fire safety of polypropylene. Ind Crops Prod2022; 184: 115002. https://doi.org/10.1016/j.indcrop.2022.115002
21.
LiuCWangHAymanM, et al. Catalytic fast pyrolysis of lignocellulosic biomass. Chem Soc Rev2014; 43: 7594–7623.
22.
CarosioFDi BlasioACutticaF, et al.Flame retardancy of polyester and polyester–cotton blends treated with caseins. Ind Eng Chem Res2014; 53(10): 3917–3923. https://doi.org/10.1021/ie404089t
BoscoFCarlettoRAAlongiJ, et al.Thermal stability and flame resistance of cotton fabrics treated with whey proteins. Carbohydr Polym2013; 94(1): 372–377. https://doi.org/10.1016/j.carbpol.2012.12.075
25.
JinXCuiSSunS, et al.The preparation and characterization of polylactic acid composites with chitin-based intumescent flame retardants. Polymers2021; 13(20): 3513. https://doi.org/10.3390/polym13203513
26.
MakhloufGAbdelkhalikAAmeenH. Preparation of highly efficient chitosan-based flame retardant coatings with good antibacterial properties for cotton fabrics. Prog Org Coating2022; 163: 106627. https://doi.org/10.1016/j.porgcoat.2021.106627
27.
PrabhakarMNRaghavendraGMVijaykumarBVD, et al.Synthesis of a novel compound based on chitosan and ammonium polyphosphate for flame retardancy applications. Cellulose2019; 26(16): 8801–8812. https://doi.org/10.1007/s10570-019-02671-y
28.
LardjaneNBelhaneche-BensemraNMassardierV. Soil burial degradation of new bio-based additives. Part I. Rigid poly(vinyl chloride) films. J Vinyl Addit Technol2011; 17(2): 98–104. https://doi.org/10.1002/vnl.20263
29.
HeinenMGerbaseAEPetzholdCL. Vegetable oil-based rigid polyurethanes and phosphorylated flame-retardants derived from epoxydized soybean oil. Polym Degrad Stabil2014; 108: 76–86. https://doi.org/10.1016/j.polymdegradstab.2014.05.024
30.
ZhangLZhangMHuL, et al.Synthesis of rigid polyurethane foams with Castor oil-based flame retardant polyols. Ind Crops Prod2014; 52: 380–388. https://doi.org/10.1016/j.indcrop.2013.10.043
31.
TurcoRMallardoSZanniniD, et al.Dual role of epoxidized soybean oil (ESO) as plasticizer and chain extender for biodegradable polybutylene succinate (PBS) formulations. Giant2024; 20: 100328. https://doi.org/10.1016/j.giant.2024.100328
32.
ChangBPThakurSMohantyAK, et al.Novel sustainable biobased flame retardant from functionalized vegetable oil for enhanced flame retardancy of engineering plastic. Sci Rep2019; 9(1): 15971. https://doi.org/10.1038/s41598-019-52039-2
33.
ZhaoPLiuZWangX, et al.Renewable vanillin based flame retardant for poly(lactic acid): a way to enhance flame retardancy and toughness simultaneously. RSC Adv2018; 8(73): 42189–42199. https://doi.org/10.1039/c8ra08531e
ZhangCJiangYLiS, et al.Recent trends of phosphorus-containing flame retardants modified polypropylene composites processing. Heliyon2022; 8(11): e11225. https://doi.org/10.1016/j.heliyon.2022.e11225
36.
InataHMatsumuraS. Chain extenders for polyesters. V. Reactivities of hydroxyl‐addition‐type chain extender; 2,2′‐bis(4h‐3,1‐benzoxazin‐4‐one). J Appl Polym Sci2003; 34: 2609–2617. https://doi.org/10.1002/app.1987.070340724
37.
InataHMatsumuraS. Chain extenders for polyesters. I. Addition-type chain extenders reactive with carboxyl end groups of polyesters. J Appl Polym Sci1985; 30(8): 3325–3337. https://doi.org/10.1002/app.1985.070300815
38.
Santonja-BlascoLRibes-GreusAAlamoRG. Comparative thermal, biological and photodegradation kinetics of polylactide and effect on crystallization rates. Polym Degrad Stabil2013; 98(3): 771–784. https://doi.org/10.1016/j.polymdegradstab.2012.12.012
39.
KhankruaRPivsa-ArtSHiroyukiH, et al.Effect of chain extenders on thermal and mechanical properties of poly(lactic acid) at high processing temperatures: potential application in PLA/polyamide 6 blend. Polym Degrad Stabil2014; 108: 232–240. https://doi.org/10.1016/j.polymdegradstab.2014.04.019
YasuniwaMTsubakiharaSSugimotoY, et al.Thermal analysis of the double-melting behavior of poly(L-lactic acid). J Polym Sci, Part B: Polym Phys2004; 42(1): 25–32. https://doi.org/10.1002/polb.10674
42.
TriamnakNSuttiruengwongSVittayakornN, et al.The properties investigations of PLA/TiO2 and PLA/doped-TiO2 composites films. Polym-Plast Technol Mater2023; 62(12): 1576–1586. https://doi.org/10.1080/25740881.2023.2222818
43.
PillinIMontrelayNBourmaudA, et al.Effect of thermo-mechanical cycles on the physico-chemical properties of poly(lactic acid). Polym Degrad Stabil2008; 93(2): 321–328. https://doi.org/10.1016/j.polymdegradstab.2007.12.005
BakerDLReynoldsMMasurelR, et al.Cooperative intramolecular dynamics control the chain-length-dependent glass transition in polymers. Phys Rev X2022; 12(2): 021047. https://doi.org/10.1103/physrevx.12.021047
46.
SchinaziGPriceEJSchiraldiDA. Chapter 3 - fire testing methods of bio-based flame-retardant polymeric materials. In: HuYNabipourHWangX (eds). Bio-Based Flame-retardant Technology for Polymeric Materials. Elsevier, 2022, pp. 61–95.
47.
JiaPZhangMLiuC, et al.Properties of poly(vinyl chloride) incorporated with a novel soybean oil based secondary plasticizer containing a flame retardant group. J Appl Polym Sci2015; 132(25): app.42111. https://doi.org/10.1002/app.42111
48.
ChenM-JWangXTaoM-C, et al.Full substitution of petroleum-based polyols by phosphorus-containing soy-based polyols for fabricating highly flame-retardant polyisocyanurate foams. Polym Degrad Stabil2018; 154: 312–322. https://doi.org/10.1016/j.polymdegradstab.2018.07.001
49.
Krawczyk-WalachMGzyra-JagiełaKMilczarekA, et al.Characterization of potential pollutants from poly(lactic acid) after the degradation process in soil under simulated environmental conditions. AppliedChem2021; 1(2): 156–172. https://doi.org/10.3390/appliedchem1020012
50.
YinWChenLLuF, et al.Mechanically robust, flame-retardant poly(lactic acid) biocomposites via combining cellulose nanofibers and ammonium polyphosphate. ACS Omega2018; 3(5): 5615–5626. https://doi.org/10.1021/acsomega.8b00540
VelencosoMMBattigAMarkwartJC, et al.Molecular firefighting—how modern phosphorus chemistry can help solve the challenge of flame retardancy. Angew Chem Int Ed2018; 57(33): 10450–10467. https://doi.org/10.1002/anie.201711735
53.
SchartelB. Phosphorus-based flame retardancy mechanisms-old hat or a starting point for future development?Materials2010; 3(10): 4710–4745. https://doi.org/10.3390/ma3104710
54.
ShekharNMondalA. Synthesis, properties, environmental degradation, processing, and applications of polylactic acid (PLA): an overview. Polym Bull2024; 81(13): 11421–11457. https://doi.org/10.1007/s00289-024-05252-7
55.
LimsukonWRubinoMRabnawazM, et al.Hydrolytic degradation of poly(lactic acid): unraveling correlations between temperature and the three phase structures. Polym Degrad Stabil2023; 217: 110537. https://doi.org/10.1016/j.polymdegradstab.2023.110537
56.
SaigusaKSaijoHYamazakiM, et al.Influence of carboxylic acid content and polymerization catalyst on hydrolytic degradation behavior of Poly(glycolic acid) fibers. Polym Degrad Stabil2020; 172: 109054. https://doi.org/10.1016/j.polymdegradstab.2019.109054
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
