# Hygroscopicity and Morphology of Bio-Based Boards--The Influence of the Formulation
## 4 Results and Discussion
### Additional Discussion  
In addition to the considerations and comparisons carried out in the previous sections, further discussions were conducted. These ensured a better understanding of the composites' properties and materials' contributions. Moreover, the benefits and drawbacks of the studied composites were pointed out, as well as their possible applications. Considering the apparent density, as the addition of _A. donax_ lowered the results of the hazelnut-shell-based composite, this could probably improve the insulation thermal \begin{table}
\begin{tabular}{l l l} \hline \hline
**Group A** & **Group B** & \(p\)**-Value * \\ \hline \multicolumn{3}{l}{Apparent Density} \\ \hline
**A. donax-based composite—A** & **Hazelnut-shell-based composite—H** & **0.012** \\ A. donax-based composite—A & Mixture-based composite—AH & 0.066 \\ Hazelnut-shell-based composite—H & Mixture-based composite—AH & 0.380 \\ \hline MBV & & \\ \hline
**A. donax-based composite—A** & **Hazelnut-shell-based composite—H** & **0.038** \\ A. donax-based composite—A & Mixture-based composite—AH & 0.136 \\ Hazelnut-shell-based composite—H & Mixture-based composite—AH & 0.968 \\ A. donax (raw material)—AA & Hazelnut shells (raw material)—HH & 0.932 \\ \hline A. donax (raw material)—AA & Mixture (raw material)—AAHH & 0.987 \\ \hline Hazelnut shells (raw material)—HH & Mixture (raw material)—AAHH & 1.000 \\ \hline \multicolumn{3}{l}{_Hazelnut shells (raw material)—HH_} & _A. donax-based composite—A_ & _0.004_ \\ \multicolumn{3}{l}{_Hazelnut shells (raw material)—HH_} & _Hazelnut-shell-based composite—H_ & _0.709_ \\ \multicolumn{3}{l}{_Hazelnut shells (raw material)—HH_} & _M Mixture-based composite—AH_ & _0.305_ \\ \multicolumn{3}{l}{_Mixture (raw material)—AAHH_} & _A. donax-based composite—A_ & _0.002_ \\ \multicolumn{3}{l}{_Mixture (raw material)—AAHH_} & _Hazelnut-shell-based composite—H_ & _0.539_ \\ \multicolumn{3}{l}{_Mixture (raw material)—AAHH_} & _Mixture-based composite—AH_ & _0.198_ \\ \multicolumn{3}{l}{_A. donax (raw material)—AA_} & _A. donax-based composite—A_ & _0.001_ \\ \multicolumn{3}{l}{_A. donax (raw material)—AA_} & _Hazelnut-shell-based composite—H_ & _0.244_ \\ \multicolumn{3}{l}{_A. donax (raw material)—AA_} & _Mixture-based composite—AH_ & _0.074_ \\ \hline Porosity & & \\ \hline A. donax-based composite—A & Hazelnut-shell-based composite—H & 0.405 \\ A. donax-based composite—A & Mixture-based composite—AH & 0.244 \\
**Hazelnut-shell-based composite—H** & **Mixture-based composite—AH** & **0.043** \\ \hline \hline \end{tabular}  
* Note: The numbers in bold represent \(p\)-values of less than 0.05; underlined results represent materials (individual) compared with each other; and italicized results represent materials (individually) compared with the composites.  
\end{table} 
Table 6: \(p\)-values of the post hoc tests for the results that were significant (considering adhesives as the variable). properties, too. Density and thermal conductivity are strictly correlated [74; 75]. However, this consideration should be verified. Hygroscopicity, porosity, and internal structure are strictly connected. The porosity includes a large range of pore sizes: macropores derived from the bio-aggregates' arrangement, mesopores within the aggregates and the adhesive, and the micropores of the aggregates and the adhesive. Even if the present study considered only the macroporosity, all these porosities affected the moisture storage capacity, together with the ratio of the aggregate/adhesive and the grain size [62; 70]. The moisture sorption/desorption capacity also depends on the surface area available for vapor exchange and other hygroscopic properties [73]. The porosity and the information about the internal structure could provide a better understanding of many other properties, too. They are strictly connected to the final performance of the composite. In addition to the hygroscopicity [62], they could influence the sound absorption and thermal insulation [76; 77].