Effect of borax-boric acid and ammonium polyphosphate on flame retardancy of natural fiber polyethylene composites


  • Ritesh Kumar
  • Jayshree Gunjal
  • Shakti Chauhan




Ammonium polyphosphate, boric acid-borax, flammability, fire retardants, thermal properties, wood polymer composite


Wood fiber filled high density polyethylene composites (WPCs) were prepared using twin screw extruder and maleated polyethylene as a coupling agent. Bamboo fibers were initially treated with alkali (NaOH), boric acid - borax (Ba-Bx) and borax (Bx). The treated and untreated fibers were used in combination with ammonium polyphosphate (APP) to investigate their synergistic effects on thermal stability, flame retardancy and mechanical properties. Alkali pretreatment (5 % NaOH) of fibers showed significant improvement in performance of APP by increasing thermal stability in WPCs. The derivative thermogravimetric (DTG) results indicate significance of Ba-Bx in promoting char induction at lower temperatures (340 ºC) and thereby, improved the thermal stability in WPCs. Flammability decreased with addition of flame retardant additives. As compared to pure WPCs, composites containing APP 10 % / Ba-Bx 5 % exhibited maximum reduction in average heat release rate (HRR) by 69 %, peak heat release rate (PHRR) by 59 %, total heat released rate (THR) by 48 % and also increased time to ignition (TTI) by 62 %. However, no significant difference was found among the combinations i.e., APP with or without compounds towards reducing the flammability of WPCs. The strength properties also reduced significantly when boron compounds were added along with APP. In general, APP alone (15 %) is enough for imparting thermal stability and flame retardancy in WPCs.    


Download data is not yet available.


ASTM 2019. D2863-19: Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (Oxygen Index). ASTM International, West Conshohocken, PA, USA. http://www.astm.org/cgi-bin/resolver.cgi?D2863

ASTM 2014. D638-14: Standard Test Method for Tensile Properties of Plastics. ASTM International: West Conshohocken, PA, USA. https://doi.org/10.1520/D0638-14

ASTM 2015. D790-15: Standard test methods for flexural properties of unreinforced and reinforced plastics and electrical insulating materials.

ASTM International: West Conshohocken, PA, USA. https://doi.org/10.1520/D0790-15

Ashori, A. 2008. Wood-plastic composites as promising green-composites for automotive industries. Bioresour Technol 99(11): 4661-4667. https://doi.org/10.1016/j.biortech.2007.09.043

Chapple, S.; Anandjiwala, R. 2010. Flammability of Natural Fiber-reinforced Composites and Strategies for Fire Retardancy: A Review. J Thermoplast Compos Mater 23(6): 871–893. https://doi.org/10.1177/0892705709356338

Chen, X.L.; Yu, J.; Guo, S.Y. 2006. Structure and properties of polypropylene composites filled with magnesium hydroxide. J Appl Polym Sci 102(5): 4943-4951. https://doi.org/10.1002/app.24938

Devi, R.R.; Gogoi, K.; Kowar, B.K.; Maji, T.K. 2013. Synergistic effect of nanoTiO2 and nanoclay on mechanical properties, flame retardancy, UV stability, and antibacterial properties of wood polymer composites. Polym Bull 70(4): 1397-1413. https://doi.org/10.1007/s00289-013-0928-x

Haykira-Acma, H. 2003. Combustion characteristic of different biomass materials. Energy convers Manag 44(1): 155-162 https://doi.org/10.1016/S0196-8904(01)00200-X

Hornsby, P.R.; Hinrichsen, E.; Tarverdi, K. 1997. Preparation and properties of polyethylene composites reinforced with wheat and flax straw fibre: Part II Analysis of composite microstructure and mechanical properties. J Mat Sci 32(4): 1009–1015. https://doi.org/10.1023/A:1018578322498

Ikhlef, S.; Nekkaa, S.; Guessoum, M.; Haddaoui, N. 2012. Effects of Alkaline Treatment on the Mechanical and Rheological Properties of Low-Density Polyethylene/Spartium junceum Flour Composites. Inter Scholar Res Notices Article ID 965101: 7p. https://doi.org/10.5402/2012/965101

Islam, Md. S.; Hamdan, S.; Jusoh, I.; Rehman, Md. R.; Ahmed, A.S. 2012. The effect of alkali pretreatment on mechanical and morphological properties of tropical wood polymer composites. Mater Des 33: 419-424. https://doi.org/10.1016/j.matdes.2011.04.044

ISO 2015. 5660-1: Reaction to fire tests-Heat release, smoke production and mass loss rate, Part 1: Heat release rate (cone calorimeter method). ISO International. https://www.iso.org/obp/ui/#iso:std:iso:5660:-1:ed-3:v1:en

Jiang, J.; Yang, Y.; Li, J. 2011. Effect of three boron flame retardants on thermal curing behavior of urea formaldehyde resin. J Therm Anal Calorim 105(1): 223-228. https://doi.org/10.1007/s10973-011-1307-1

Kozlowski, R.; Wesolek, D.; Wladyka-Przbylak, M. 1999. Combustibility and toxicity of board materials used for interior fittings and decorations. Polym Degrad Stab 64(3): 595-600. https://doi.org/10.1016/S0141-3910(98)00146-3

Kozlowski, R.; Wladyka-Przbylak, M. 2008. Flammability and fire resistance of composites reinforced by natural fibers. Polym Adv Technol 19(6): 446-453. https://doi.org/10.1002/pat.1135

Kurt, R.; Mengeloglu, F.; Meric, H. 2012. The effects of boron compounds synergists with ammonium polyphosphate on mechanical properties and burning rates of wood-HDPE polymer composites. Eur J Wood Prod 70(1-3): 177-182. https://doi.org/10.1007/s00107-011-0534-2

Kumar, R.; Chandrashekar, N. 2014. Fuel properties and combustion characteristics of some promising bamboo species in India. J For Res 25(2): 471-476. https://doi.org/10.1007/s11676-014-0478-6

Kumar, R.; Gunjal, J.; Chauhan, S. 2021. Effect of carbonization temperature on properties of natural fiber and charcoal filled hybrid polymer composite. Compos B: Eng 217: 108846. https://doi.org/10.1016/j.compositesb.2021.108846Get

Lee, S.Y.; Chun, S.J.; Doh, G.H.; Kang, I.A.; Lee, S.; Paik, K.H. 2009. Influence of Chemical Modification and Filler Loading on Fundamental Properties of Bamboo Fibers Reinforced Polypropylene Composites. J Compos Mater 43(15): 1639–1657. https://doi.org/10.1177/0021998309339352

LeVan, S.L. 1984. Chemistry of fire retardancy. The chemistry of solid wood. In Advances in chemistry series: 207p. Rowell, R. (ed). American Chemical Society, Washington, D.C., USA. https://pubs.acs.org/doi/abs/10.1021/ba-1984-0207.ch014

Mouritz, A.P.; Gibson, A.G. 2006. Flame Retardant Composites. In Fire Properties of Polymer Composite Materials: 237-286. Gladwell, G.M.L. (ed.). Springer, London, UK.

Nagieb, Z.A.; Nassar, M.A.; El-Meligy, M.G. 2011. Effect of Addition of Boric Acid and Borax on Fire-Retardant and Mechanical Properties of Urea Formaldehyde Saw Dust Composites. Inter J Carbohydrate Chem Article ID 146763. http://downloads.hindawi.com/archive/2011/146763.pdf

Palza, H.; Reznik, B.; Kappes, M.; Hennrich. F.; Naue, I.F.C.; Wilhelm, M. 2010. Characterization of melt flow instabilities in polyethylene/carbon nanotube composites. Polymer 51(16): 3753-3761. https://doi.org/10.1016/j.polymer.2010.06.016

Pan, M.; Mei, C.; Du, J.; Li, G. 2014. Synergistic effect of nano silicon dioxide and ammonium polyphosphate on flame retardancy of wood fiber-polyethylene composites. Compos Part A 66: 128-134. https://doi.org/10.1016/j.compositesa.2014.07.016

Panagiotou, T.; Levendis, Y.A. 1994. Study on the combustion characteristics of PVC, poly (styrene), poly (ethylene), and poly (propylene) particles under high heating rates. Combust Flame 99(1): 53-63. https://doi.org/10.1016/0010-2180(94)90082-5

Salemane, M.G.; Luyt, A.S. 2006. Thermal and mechanical properties of polypropylene-wood powder composites. J Appl Polym Sci 100(5): 4173-4180. https://doi.org/10.1002/app.23521

Schneider, M.H.; Phillips, J.G.; Lande, S. 2000. Physical and mechanical properties of wood polymer composites. J Forest Eng 11(1): 83-89. https://doi.org/10.1080/08435243.2000.10702748

Shafizadeh, F. 1984. The Chemistry of Pyrolysis and Combustion. In The Chemistry of Solid Wood. Advances in Chemistry Series 207: 489-529. Rowell, R. (ed.). American Chemical Society, Washington, D.C., USA. https://pubs.acs.org/doi/abs/10.1021/ba-1984-0207.ch013

Stark, N.M.; White, R.H.; Mueller, S.A.; Osswald, T.A. 2010. Evaluation of various fire retardants for use in wood flour–polyethylene composites. Polym Degrad Stab 95(9): 1903-10. https://doi.org/10.1016/j.polymdegradstab.2010.04.014

Wang, Y.; Simonsen, J.; Neto, C.P.; Rocha, J.; Rials, T.G.; Hart, E. 1996. The reaction of boric acid with wood in a polystyrene matrix. J Appl Polym Sci 62(3): 501-508. https://doi.org/10.1002/(SICI)1097-4628(19961017)62:3%3C501::AID-APP8%3E3.0.CO;2-U

Wang, Q.W.; Li, J.; Winandy, E.J. 2004. Chemical mechanism of fire retardance of boric acid on wood. Wood Sci Technol 38(5): 375-389




How to Cite

Kumar, R. ., Gunjal, J. ., & Chauhan, S. . (2022). Effect of borax-boric acid and ammonium polyphosphate on flame retardancy of natural fiber polyethylene composites. Maderas-Cienc Tecnol, 24, 1–10. https://doi.org/10.4067/s0718-221x2022000100434