Surface coated ZnO powder as flame retardant for wood: A short communication

Olina Öhrn; Kesavarao Sykam; Sidique Gawusu; Rhoda Afriyie Mensah; Michael Försth; Vigneshwaran Shanmugam; N B Karthik Babu; Gabriel Sas; Lin Jiang; Qiang Xu; Ágoston Restás; Oisik Das

doi:10.1016/j.scitotenv.2023.165290

Surface coated ZnO powder as flame retardant for wood: A short communication

Sci Total Environ. 2023 Nov 1:897:165290. doi: 10.1016/j.scitotenv.2023.165290. Epub 2023 Jul 3.

Authors

Affiliations

¹ Structural and Fire Engineering Division, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå 97187, Sweden.
² Polymers & Functional Materials Division, Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, Telangana, India.
³ Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218, United States.
⁴ Department of Mechanical Engineering, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai 602 105, Tamil Nadu, India. Electronic address: s.vigneshwaren@gmail.com.
⁵ Department of Mechanical Engineering, Assam Energy Institute, A Centre of Rajiv Gandhi Institute of Petroleum Technology, Sivasagar 785697, India.
⁶ School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
⁷ Department of Fire Protection and Rescue Control, National University of Public Service, 1011, Budapest, Hungary.
⁸ Structural and Fire Engineering Division, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå 97187, Sweden. Electronic address: oisik.das@ltu.se.

PMID: 37406703
DOI: 10.1016/j.scitotenv.2023.165290

Abstract

In the present study, the ability of a coating of zinc oxide (ZnO) powder to improve the fire-safety of wood exposed to radiative heat flux was examined, focusing on the ignition time of the wood. To test ZnO's efficiency on the wood substrate, two different amounts of ZnO (0.5 and 1 g ZnO per dm²) were applied to the wood surface and exposed to radiative heat from a cone calorimeter wherein a pristine piece of wood with no ZnO treatment was taken as control. The experiments were conducted at three different irradiation levels i.e., 20, 35, and 50 kWm^-2. The results showed that applying ZnO on the surface of the wood significantly increased the ignition time (TTI). For the three different heat fluxes, using 0.5 g ZnO per dm² coating on the wood surface increased the TTI by 26-33 %. Furthermore, the application of 1 g of ZnO per dm² generated a TTI increment of 37-40 %. All three irradiation levels showed similar trends in TTI. The micrographs taken before and after combustion showed no significant disparity in the morphology of ZnO. The agglomerated ZnO particles on the wood surface remained intact after combustion. This study demonstrates a facile method of using ZnO to delay the ignition of wood. This could potentially impart fire-safety to wooden structures/façades in wildland-urban interfaces and elsewhere by reducing flame spread.

Keywords: Cone calorimeter; Fire; Flame retardancy; Wildland-urban interface; Wood; ZnO.