Page 17 - InnoRenew CoE International Conference 2024

Biobased fl ame-retardant coating for wooden facades

Laetitia Marrot *, Mariem Zouari , Ulises Rojas-Alva 1
2,3
1
1 Slovenian National Building and Civil Engineering Institute (ZAG), Dimičeva ulica 12, 1000 Ljubljana, Slovenia, laetitia.marrot@zag.si,
ulises.rojas-alva@zag.si
2 InnoRenew CoE, Livade 6a, 6310 Izola, Slovenia, mariem.zouari@innorenew.eu
3 Faculty of Mathematics, Natural Sciences and Information technologies; University of Primorska, Muzejski trg 2, 6000 Koper, Slovenia

As a combustible material, wood can benefi t from the application of a flame-retardant coating to delay its ignition

and improve its performance toward fire. Phytic acid is a non-toxic phosphorus component naturally occurring in plant
tissues. Phosphorus flame retardants can form protective char layers, which affects self-extinguishing and protects

the material exposed to fire from the spread of the flame. To enhance the formation of a stable aromatic char layer,

a carbon source can be combined with the phosphorus containing fire retardant (Barbalini et al., 2020, Yang et al.,

2018).
In this study, the fire protective effects of biobased coatings for wooden surfaces were investigated. The coatings are

composed of tung oil in which different ratios of biochar/phytic acid binary blend were integrated (0, 10 and 20 wt%). A
spruce substrate was selected for the application of coatings. Cone calorimetry tests were carried out on wood coated
with different formulations to comprehensively study the contribution of each component (i.e., tung oil, biochar, and

phytic acid) to the fire. Irradiative heat fluxes of 50, 35, and 25 kW/m² were used in horizontal configuration.

The introduction of tung oil delayed the ignition slightly compared to the untreated sample, which was expected as
slightly more energy is required to break down the oil to gas-phase.

On the contrary, the biochar layer aided ignition given that the black surface has a higher absorptivity (close to unity)
than virgin wood. Since the treatment was applied on the surface, this mostly modified the ignition behavior either

negatively or positively.

Then, once the sample in-depth was involved in the (steady burning) process, the superficial treatment bore no eff ect
on the overall burning. For the next phase, the introduction of phytic acid is expected to counteract the biochar layer’s
positive effect on ignition delay time.

Keywords: biobased flame retardant, wood coating, cone calorimeter, phytic acid, biochar

Acknowledgment: The authors gratefully acknowledge receiving funding from the European Union's Horizon 2020
research and innovation programme, #952395, the H2020 WIDESPREAD-2-Teaming: #739574 and the Republic of
Slovenia.

REFERENCES

Barbalini, M. , Bartoli, M., Tagliaferro, A., Malucelli, G.,2020. Phytic Acid and Biochar: An Effective All Bio-Sourced Flame
Retardant Formulation for Cotton Fabrics. Polymers. 12(4), 811. https://doi: 10.3390/polym12040811.

Yang, W., Tawiah, B., Yu, C., Qian, Y.-F., Wang, L.-L., Chun-Yin Yuen A., Zhu, S., Hu, E., Bo-Yuan Chen, T., Yu, B., Lu, H., Heng Yeoh,

G., Wang, X., Song, L., Hu, Y., 2018. Manufacturing, mechanical and flame retardant properties of poly(lactic acid) biocomposites
based on calcium magnesium phytate and carbon nanotubes. Compos. Part Appl. Sci. Manuf. 110, 227–236. https://doi:
10.1016/j.compositesa.2018.04.027.

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