Evaluation of wood treated with Paraloid B72® and boric acid: thermal behavior, water absorption and mold resistance

Consolidation of wood is one of the actions to be taken once wood materials are degraded by biotic or abiotic factors to keep its structural functions. While maintaining structural integrity is a priority in consolidation work, consolidant system should also be compatible and must allow the combination of additives. Besides improved performance, proper protection against thermal degradation is needed as well when consolidated wood is subjected to elevated temperatures. Mass loss calorimeter tests and thermogravimetric analyses of wood treated with Paraloid B72 (R) copolymer and boric acid were first performed. Effects of the copolymer on boron leaching and mold resistance of the Paraloid B72 (R)-modified specimens were also studied. Water absorption and wettability tests, FTIR and SEM evaluations were performed for characterization on the specimens after modifications with Paraloid B72 (R). Mass loss calorimeter tests indicated that Paraloid B72 (R) treatments alone decreased the fire resistance of test specimens; however, incorporation of boric acid into Paraloid B72 (R)-treated specimens enhanced the fire resistance. Thermogravimetric analyses showed significant increases in boric acid and Paraloid B72 (R)-treated specimens when compared to Paraloid B72 (R) treatments alone. Paraloid B72 (R) copolymer treatments resulted in less water absorption values in the specimens; however, the copolymer did not effectively limit boron release from modified specimens. While Paraloid B72 (R) treatments increased the hydrophobicity of the specimens, boric acid has partial effect on the wetting properties. No mold inhibition was seen in Paraloid B72 (R) only treated specimens; however, significantly lower mold growth rates were observed in boric acid and Paraloid B72 (R)-treated specimen by vacuum.

Automated summary

Consolidation of wood is essential for maintaining its structural functions after degradation, and the choice of consolidant system should be compatible and allow the use of additives. The addition of boric acid enhanced the fire resistance of Paraloid B72 (R)-treated specimens, and thermogravimetric analyses showed increased resistance to thermal degradation. Paraloid B72 (R) treatments reduced water absorption and increased hydrophobicity, but did not effectively limit boron leaching. Vacuum treatment with boric acid and Paraloid B72 (R) resulted in lower mold growth rates compared to Paraloid B72 (R) treatment alone.