## 3 Results and Discussion
### Fire Performance of Wood Parts Coated with PVAc-Bioadditive IFR Adhesive Blends  
Table 8 and Figure 7 show the fire performance, mass loss, and carbonization index results of the specimens coated with five PVAc-bioadditive adhesive blends selected and evaluated as coatings on wood pieces. We also included specimens of untreated wood and wood treated with pure or standard PVAc adhesive. \begin{table}
\begin{tabular}{c c c} \hline \hline
**PVAc-Bioadditive IFR** & **Mass Loss (\%)** & **Carbonization Index (\%)** \\
**Adhesive Blends** & & \\ \hline Untreated & 83.07 \({}^{\text{d}}\)\(\pm\) 3.71 & 77.62 \({}^{\text{c}}\)\(\pm\) 6.21 \\ \hline PVAc & 10.24 \({}^{\text{b}}\)\(\pm\) 0.98 & 13.18 \({}^{\text{b}}\)\(\pm\) 13.85 \\ \hline PVAc-2.5\% F1 & 9.28 \({}^{\text{b}}\)\(\pm\) 0.99 & 4.31 \({}^{\text{ab}}\)\(\pm\) 1.00 \\ \hline PVAc-12.5\% F1 & 7.81 \({}^{\text{c}}\)\(\pm\) 1.49 & 3.76 \({}^{\text{ab}}\)\(\pm\) 0.70 \\ \hline PVAc-2.5\% F2 & 10.79 \({}^{\text{ab}}\)\(\pm\) 0.78 & 3.11 \({}^{\text{a}}\)\(\pm\) 0.91 \\ \hline PVAc-5\% F2 & 10.53 \({}^{\text{c}}\)\(\pm\) 1.24 & 5.48 \({}^{\text{ab}}\)\(\pm\) 0.55 \\ \hline PVAc-12.5\% F2 & 6.10 \({}^{\text{a}}\)\(\pm\) 2.30 & 3.89 \({}^{\text{ab}}\)\(\pm\) 1.07 \\ \hline \hline \end{tabular} The results correspond to the mean \(\pm\) St. Dev. \({}^{\text{a}}\)\(\pm\)\(\delta\) reflect statistically significant differences, according to LSD test with 95% confidence interval (no statistically significant differences between levels sharing the same column or letter). Stagraphics Centroium XVII 19-X 64 software.  
\end{table} 
Table 8: Average mass loss and carbonization index values in wood pieces coated with PVAc-bioadditive IFR adhesive blends. Figure 6: Adhesive penetration and glue line morphology: (**a**) PVAc adhesive line; (**b**) PVAc-12.5% F2 adhesive line. In general, the mass loss of the wood pieces coated with the adhesive blends and tested in a fire chamber ranged from 6.10% to 83.07%. Likewise, the carbonization index ranged from 3.11% to 77.62%. The lowest mass loss values were 6.10% and 7.81% for the wood pieces treated with the PVAc-12.5% F2 and PVAc-12.5% F1 adhesive blends, respectively. On the other hand, the lowest magnitudes of the carbonization index were presented in wood pieces treated with the adhesive blends PVAc-2.5% F2 and PVAc-12.5% F1, with values of 3.11% and 3.76%, respectively. The statistical analysis showed a significant difference in mass loss between the wood pieces coated with the PVAc-12.5% F2 adhesive blend and those treated with the standard adhesive, as well as those not coated. As for the carbonization index, a significant difference was observed between the pieces treated with the PVAc-2.5% F2 adhesive blend, and those coated with the pure PVAc adhesive, as well as with the untreated pieces. The results of the fire resistance tests indicate that the PVAc-12.5% F2 and PVAc-2.5% F2 adhesive blends protect wood better against fire than the unmodified PVAc adhesive, according to the mass loss and carbonization index indicators. ML is a more accurate indicator that confirms the effectiveness of the IFR bioadditive, which includes LS and Mg(OH)\({}_{2}\). In addition, the higher concentration of Mg(OH)\({}_{2}\) in the F2 formulation was crucial to improve the fire performance, which is in agreement with previous research that showed that the combination of Mg(OH)\({}_{2}\) and lignin thermally strengthens the materials, highlighting the effect of Mg(OH)\({}_{2}\) on thermal stability [84]. Determination of VOC Emissions in the Combustion of Wood Coated with Unmodified and Modified PVAc Adhesive Using the IFR Bioadditive Formulations  
It is important to remember that dry wood (8 to 12% moisture content) and untreated wood react with fire mainly because of the carbohydrates that compose it (65 to 75%) [85], whose chemical structure is based on compounds of hydrogen, oxygen, and carbon, highly flammable and typical of organic materials [86], considering that volatile organic compounds (VOCs) emissions increase with temperature [87].