## 3 Results
They form approximately 90% of the wood mass volume. Spring wood exhibits larger cell diameters, thinner walls and smaller cellular cavities. Cells of summer wood have smaller diameters, thicker walls and smaller cellular cavities. On the basis of different studies [20], it may be stated that the absorptivity of sawdust is affected by its structure. Figure 11 shows the structures of pine and oak obtained using an electron microscope; they indicate that pine has thin capillaries and this may cause worse pelletisability when compared to oak. Thin tracheids--capillaries--in pine had a significant effect on capillarity. A correlation should be sought in capillary pressure. During wetting, the liquid level in the capillary rises, and if the material is unwettable, the liquid level is pressed below the level of the surrounding liquid. The performed investigation showed that wood and plant biomasses exhibit certain structural differences which result in different behaviours of biomass during pre-treatment within the sintering process. Figure 12 presents a microscopic view of the structures of plant biomass made of lavender and Miscanthus. The structure of Miscanthus sinensis and Lavandula angustifolia was observed on the Leica Wild M3Z stereomicroscope. Figure 11: Structure of pine (**A**) and oak (**B**) [20]. Microscopic observations of both types of biomass showed that the structures of both lavender and Miscanthus are very similar; they consist of smaller enclosed pores. In lavender, the pores are evenly distributed. In Miscanthus, however, there were differences in form of a significantly larger pore in the central part of the plant. The lower absorptivity of lavender, compared to Miscanthus, may be explained by comparing the structures of both plants in the longitudinal cross-section in terms of specific surface, as shown in Figure 13. After identical magnification of both plants, the specific surface of Miscanthus was 3-fold larger than specific surface of lavender. The present article points out the importance of investigation of biomass properties within a deeper context and of the search for potential optimisation and utilization of biomass. Table 3 shows the maximum values of absorptivity with the use of different liquids and with different granulometric compositions of biomass. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Granulometry** & **Warm Water** & **Cold Water** & **Soap Water** & **Tenzide** \\  & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** \\ \hline \multirow{2}{*}{**Lavender Angustifolia**} & 0.5 & 10 & 4 & 15 & 14 \\  & 0.5–1 & 10 & 9 & 12 & 22 \\  & 1–2 & 4 & 6 & 4 & 9 \\ \hline \multirow{3}{*}{**Miscanthus Sinensis**} & 0.5 & 15 & 11 & 19 & 34 \\  & 0.5–1 & 11 & 15 & 20 & 18 \\  & 1–2 & 6 & 9 & 5 & 15 \\ \hline \multirow{3}{*}{**Scots Pine**} & 0.5 & 12 & 6 & 6 & 13 \\  & 0.5–1 & 10 & 2 & 15 & 14 \\ \cline{1-1}  & 1–2 & 10 & 1 & 15 & 16 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Maximum values of absorptivity. Figure 12: Structure of Miscanthus sinensis (**a**) and Lavandula angustifolia (**b**). Figure 13: Structure of Miscanthus (**a**) and (**b**) lavender in a longitudinal cross-section. The table clearly shows that the most significant values of absorptivity were achieved in the majority of the examined samples with the use of tensile. The highest absorptivity, as much as 34 mm, was observed with Miscanthus sinensis at a fraction below 0.5 mm. As for wood biomass, better absorptivity was observed with English oak; with the use of tensile, the highest value was 28 mm at a fraction of 0.5-1 mm. If we compare absorptivity values in terms of granulocyte, more significant differences were observed with plant biomass at a fraction of 0.5 and 0.5-1. A fraction of 1-2 mm exhibited very low absorptivity in both types of plant biomass, except for the case when tensile was used with Miscanthus.