## 4 Discussion  
### ISO 5660-1 Test  
Through ISO 5660-1 testing, we investigated the impact of variations in the particle size of magnesium hydroxide on the fire performance and combustion by-products of cellulose-based building finishing materials.  
Figure 11 shows the THR at 600 s as well as the trendline with respect to varying magnesium hydroxide addition amounts. It can be seen that the flame-retardant magnesium hydroxide addition and THR results are inversely proportional to each other. As the amount of magnesium hydroxide addition increases, a more consistent fire performance is observed.  
The variation in THR results with respect to magnesium hydroxide addition is expressed by Equation (5):  
\[y\ =\ 0.0121x^{2}\ -\ 0.7693x\ +\ 24.9 \tag{5}\]  
where  
\(y\) = THR at 600 s.  
\(x\) = magnesium hydroxide addition amount.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample Type**} & \multicolumn{10}{c}{**Toxic Gas**} \\ \cline{2-13}  & **CO\({}_{2}\)** & **CO** & **H\({}_{2}\)S** & **NH\({}_{3}\)** & **HCHO** & **HCI** & **SO\({}_{2}\)** & **CH\({}_{2}\)CHCN** & **NO\({}_{k}\)** & **C\({}_{k}\)H\({}_{5}\)OH** & **HCN** & **HBr** & **HF** \\ \hline B-3 & 2900 & 130 & 0 & 0 & 0 & 0 & 0 & 0 & 0.  
Figures 12 and 13, respectively, compare the quantified measurements of \(CO\) and CO\({}_{2}\) gases over time in ISO 5660-1 experiments conducted with varying magnesium hydroxide addition amounts as the variable. The quantification equations for the gases generated in the ISO 5660-1 experiment were organized and calculated as expressed in Equations (6) and (7).  
\[CO\] Production Index \[= \int_{0}^{600}CO\] Production (6)  
\[CO_{2}\] Production Index \[= \int_{0}^{600}CO_{2}\] Production (7)  
Figure 12: CO Production Index and trend line: (**A**) Mg(OH)\({}_{2}\) 0 g; (**B**) Mg(OH)\({}_{2}\) 10 g; (**C**) Mg(OH)\({}_{2}\) 20 g; (**D**) Mg(OH)\({}_{2}\) 30 g.  
Figure 13: CO\({}_{2}\) Production Index and trend line: Mg(OH)\({}_{2}\) 0 g; Mg(OH)\({}_{2}\) 10 g; Mg(OH)\({}_{2}\) 20 g; Mg(OH)\({}_{2}\) 30 g.  
The correlation between changes in magnesium hydroxide addition and the generation of each of CO and CO2 in cellulose specimens was examined. It was observed that an increase in magnesium hydroxide led to incomplete combustion, thus resulting in a decrease in carbon dioxide generation and an increase in carbon monoxide generation.  
The variation in the CO Index with respect to magnesium hydroxide addition is expressed by Equation (8), while the corresponding variation in the CO2 Index is represented by Equation (9):  
\[y=-0.0001x^{2}+0.0827x+3.3433 \tag{8}\]  
where  
\(y=\) CO Index.  
\(x=\) magnesium hydroxide addition amount.  
\[y=0.034x^{2}-2.156x+96.045 \tag{9}\]  
where  
\(y=\) CO2 Index.  
\(x=\) magnesium hydroxide addition amount.  
Table 8 represents the initial mass and the mass after the ISO 5660-1 experiment. Utilizing the mass data recorded during the ISO 5660-1 experiment, the analysis of the mass loss rate variation with changes in magnesium hydroxide addition was conducted by comparing the initial mass with the mass at the end of the experiment. The equation for calculating the mass loss rate of the specimens during the experiment is given by Equation (9), and Figure 14 illustrates the distribution of mass loss rates along with the trendline with respect to varying magnesium hydroxide addition amounts.  
\[\text{Mass Loss Rate}\left(\%\right)=\frac{\text{{Initial Mass}}-\text{{After Test Mass}}}{\text{{Initial Mass}}}\times 100 \tag{10}\]  
The analysis of the mass loss rate revealed that as the magnesium hydroxide addition increased, the mass loss rate decreased.  
The variation in the mass loss rate results with respect to magnesium hydroxide addition is expressed by Equation (11),  
\[y=0.0095x^{2}-0.8975x+38.621 \tag{11}\]  
where  
\(y=\) mass loss rate (%).  
\(x=\) magnesium hydroxide addition amount.