Wood–plastic composites are composite materials consisting of wood particles, thermoplastic polymer, and small amounts of other performance additives to increase performance in exterior construction applications such as decking and siding. Three best-performing fire retardants, determined from a previous study, which were brominated, magnesium hydroxide, and ammonium polyphosphate, were selected for this weathering study and more detailed analysis with color analysis, thermogravimetric analysis/differential scanning calorimetry, and the cone calorimeter. With the rapid surface heating condition at cone calorimeter irradiance of 50 kW m−2, modest surface leaching of fire retardant was detected as caused by weathering via increased first peak heat-release rate and reduced time to ignition values. Otherwise, the weathering had minimal effect on the remaining heat-release rate profile, and results confirmed ammonium polyphosphate as top performing fire retardant, even better than Ipe wood, with magnesium hydroxide and brominated slightly worse than Ipe. This suggests that 35% high-density polyethylene content reduced fire retardant bulk leaching.
WhiteRHDietenbergerMAStarkNM. Cone calorimeter tests of wood-based decking materials. In: Proceedings eighteenth annual BCC conference on flame retardancy, Stamford, CT, 21–23 May 2007, pp. 326–337. Stamford, CT: BCC Research.
5.
SeefeldtHBraunU.A new flame retardant for wood materials tested in wood plastic composites. Macromol Mater Eng2012; 297: 814–820.
6.
BorysiakSPauksztaDHelwigM.Flammability of wood-polypropylene composites. Polym Degrad Stab2006; 91(12): 3339–3343.
7.
ChappleSAnandjiwalaR.Flammability of natural fiber-reinforced composites and strategies for fire retardancy: a review. J Thermoplast Compos Mater2010; 23: 871–893.
8.
TshaiKYKongI. Advancement in flame retardancy of natural fibre reinforced composites with macro to nanoscale particulates additives. In: GohKLAswathiMKDe SilvaRT, et al. (eds) Interfaces in particle and fibre reinforced composites. Sawston: Woodhead Publishing, 2020, pp. 311–342.
9.
SainMParkSHSuharaF, et al. Flame retardant and mechanical properties of natural fibre-PP composites containing magnesium hydroxide. Polym Degrad Stab2004; 83(2): 363–367.
ShenKKOlsonE.The use of borates and talc as fire retardants in wood plastic composite. In: Proceedings seventeenth annual BCC conference on flame retardancy. Stamford, CT, 22–24 May 2006, pp. 289–296. Stamford, CT: BCC Research.
12.
AyrilmisNAkbulutTDundarT, et al. Effect of boron and phosphate compounds on physical, mechanical, and fire properties of wood-polypropylene composites. Constr Build Mater2012; 33: 63–69.
13.
GarcíaMHidalgoJGarmendiaI, et al. Wood-plastic composites with better fire retardancy and durability performance. Composites A2009; 40: 1772–1776.
14.
Abu BakarMBMohd IshakZAMat TaibR, et al. Flammability and mechanical properties of wood flour filled polypropylene composites. J Appl Polym Sci2010; 116: 2714–2722.
15.
ZhangZXZhangJLuB-X, et al. Effect of flame retardants on mechanical properties, flammability, and foamability of PP/wood-fiber composites. Composites B2012; 43: 150–158.
16.
LiBHeJ.Investigation of mechanical property, flame retardancy and thermal degradation of LLDPE-wood-fibre composites. Polm Degrad Stab2004; 83(2): 241–246.
17.
KalaliENZhangLShabestariME, et al. Flame-retardant wood polymer composites (WPCs) as potential fire safe bio-based materials for building products: preparation, flammability and mechanical properties. Fire Saf J2019; 107: 210–216.
18.
KrehulaLKKatančićZMarićG, et al. Study of fire retardancy and thermal and mechanical properties of HDPE-wood composites. J Wood Chem Technol2015; 35: 412–423.
19.
PanMMeiCDuJ, et al. Synergistic effect of nano silicon dioxide and ammonium polyphosphate on flame retardancy of wood fiber-polyethylene composites. Composites A2014; 66: 128–134.
20.
AraoYNakamuraSTomitaY, et al. Improvement on fire retardancy of wood flour/polypropylene composites using various fire retardants. Polym Degrad Stab2014; 100: 79–85.
21.
StarkNMMuellerSAWhiteRH, et al. Evaluation of Various Fire Retardants for Use in Wood Flour/Polyethylene Composites. Polym Degrad Stab2010; 95(9): 1903–1910.
22.
SchirpASuS.Effectiveness of pre-treated wood particles and halogen-free flame retardants used in wood-plastic composites. Polym Degrad Stab2016; 126: 81–92.
23.
SchirpAHellmannnA.Fire retardance improvement of high-density polyethylene composites based on thermomechanical pulp treated with ammonium polyphosphate. Polym Compos2019; 10: 2410–2423.
24.
BraunUWachtendorfVGeburtigA, et al. Weathering resistance of halogen-free flame retardance in thermoplastics. Polym Degrad Stab2010; 95: 2421–2429.
25.
VahabiHSonnierRFerryL.Effects of ageing on the fire behaviour of flame-retarded polymers. Polym Int2015; 64: 313–328.
26.
StarkNMMatuanaLM.Effect of processing method on surface and weathering characteristics of wood-flour/HDPE composites. J Appl Polym Sci2004; 93(3): 1021–1030.
27.
SchirpASchwarzB.Influence of compounding conditions, treatments of wood particles with fire-retardants and artificaial weathering on properties of wood-polymer composites for façade applications. Eur J Wood Wood Prod2021; 79: 821–840.
28.
LyonRE.Chapter 11 solid state thermochemistry of flaming combustion. In: GrandAFWilkieCA (eds) Fire retardancy of polymeric materials. New York: Marcel Dekker, Inc., 2000, pp. 391–447.
29.
GeorlettePSimonsJCostaL.Halogen-containing fire-retardant compounds. In: GrandAFWilkieCA (eds) Fire retardancy of polymeric materials. New York: Marcel Dekker, Inc., 2000, p. 245.
30.
WeilED.Synergists, adjuvants, and antagonists in flame-retardant systems. In: GrandAFWilkieCA (eds) Fire retardancy of polymeric materials. New York: Marcel Dekker, Inc., 2000, p. 115.
31.
GreenJ.Phosphorous-containing flame retardants. In: GrandAFWilkieCA (eds) Fire retardancy of polymeric materials. New York: Marcel Dekker, Inc., 2000, p. 147.
32.
JosephPEbdonJR.Chapter 5 phosphorus-based flame retardants. In: WilkieCAMorganAB (eds) Fire retardancy of polymeric materials. 2nd ed.Boca Raton, FL: CRC Press, 2010, pp. 107–127.
33.
ASTM D7032:2021. Standard specification for establishing performance ratings for wood-plastic composite and plastic lumber deck boards, stair treads, guards, and handrails.
34.
ASTM Standard D 2898. Annual book of ASTM standards (8.01). Conshocken, PA: American Society for Testing and Materials, 2008.
35.
ASTM D2565:2023. Standard practice for xenon-arc exposure of plastics intended for outdoor applications.
36.
TangWKEicknerHW.Effect of inorganic salts on pyrolysis of wood, cellulose, and lignin determined by differential thermal analysis. USDA Forest Service research paper FPL 82, January 1968. Washington, DC: USDA Forest Service
37.
RowellRMDietenbergerMA. Chapter 6. Thermal properties, combustion, and fire retardancy of wood. In: RowellR (ed.) Handbood of wood chemistry and wood composites. 2nd ed.Boca Raton, FL: CRC Books, 2013, pp. 127–149, https://www.fs.usda.gov/research/treesearch/41925
38.
CordeiroIChenTYuenA, et al. Pyrolysis and combustion characterization of HDPE/APP composites via molecular dynamics and CFD simulations. J Anal Appl Pyrolysis2022; 163: 105499.
39.
ASTM D2244:2023. Standard practice for calculation of color tolerances and color differences from instrumentally measured color coordinates.
40.
ASTM E1354:2023. Standard test method for heat and visible smoke release rates for materials and products using and oxygen consumption calorimeter.
41.
ASTM E 2102:2021. Standard test method for measurement of mass loss and ignitability for screening purposes using a conical radiant heater.
42.
AS 3959. Construction of Buildings in Brushfire Prone Areas - Western Australia. (Standards Australia 2018c).
43.
SFM 12-7A-4. Materials and Construction Methods for Exterior Wildfire Exposure - Decking SFM Standard. (California State Fire Marshall 2016).
44.
WhiteRStarkNAvrilmisN. Recent activities in flame retardancy of wood-plastic composites at the Forest Products Laboratory. In: 22nd annual conference on recent advances in flame retardancy of polymeric materials, Stamford, CT, 23–25 May 2011.
45.
StarkN. Considerations in the weathering of wood-plastic composites. In: Proceedings: 3rd wood fibre polymer composites international symposium: innovative sustainable materials applied to building and furniture, Bordeaux, 26–27 March 2007.
46.
DietenbergerMA.Pyrolysis kinetics and combustion of thin wood by an advanced cone calorimetry test method. J Therm Anal Calorim2012; 109: 1215–1228, https://www.fs.usda.gov/research/treesearch/41242
47.
ChoJDavisJMHuberGW.The intrinsic kinetics and heats of reactions for cellulose pyrolysis and char formation. ChemSusChem2010; 3: 1162–1165.
48.
WernerKPommerLBroströmM.Thermal decomposition of hemicelluloses. J Anal Appl Pyrolysis2014; 110: 130–137.
49.
KuangKHuangXLiaoG.A comparison between superfine magnesium hydroxide powders and commercial dry powders on fire suppression effectiveness. Process Saf Environ Prot2008; 86: 182–188.
50.
FernandesVJFernandesNSFonsecaVM, et al. Kinetic evaluation of decabromodiphenil oxide as a flame retardant for unsaturated polyester. Thermochim Acta2002; 388(1–2): 283–288.
51.
WuYYaoCHuY, et al. Comparative performance of three magnesium compounds on thermal degradation behavior of red gum wood. Materials2014; 7: 637–652.
DietenbergerMAGrexaO. Ignitability of materials in transitional heating regimes. In: Wood & fire safety: proceedings, 5th international scientific conference, Zvolen, 18–22 April 2004, pp. 31–41. Zvolen: Faculty of Wood Sciences and Technology, Technical University of Zvolen.
54.
DietenbergerMAWhiteRH. Reaction-to-fire testing and modeling for wood products. In: Proceedings, 12th annual BCC conference on flame retardancy, Stamford, CT, 21–23 May 2001, pp. 54–69. Nonvalk, CT: Business Communications Co., Inc.
55.
ASTM E84:2023c. Standard test method for surface burning characteristics of building materials.
