## 3 Results and Discussion
### Dsc  
Differential scanning calorimetry (DSC) tests were carried out in two cycles of heating and cooling in the temperature range of 20-220 \({}^{\circ}\)C and at a 10 \({}^{\circ}\)C/min heating rate in \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**PLA/**} & \multirow{2}{*}{**Alcohol Boiling Point [\({}^{\circ}\)C]**} & **pKa Alcohol (from PuB Chem)** & **Tensile Strength [MPa]** & **Impact Strength [\%] 1 Cycle** & **Crystallinity [\%] 2 Cycle** \\ \hline neat & - & - & 56.8 & 15.4 & 13.64 & 3.40 \\ \hline MeOH & 65.0 & 15.3 (at 25 \({}^{\circ}\)C) & 67.22 & 17.9 & 20.61 & 6.39 \\ \hline EtOH & 78.2 & 15.9 (at 25 \({}^{\circ}\)C) & 54.39 & 15.3 & 19.42 & 4.15 \\ \hline i-PrOH & 83.0 & 17.1 & 45.07 & 14.9 & 21.55 & 4.44 \\ \hline BnOH & 205.3 & 15.4 & 35.99 & 17.2 & 23.71 & 18.72 \\ \hline CyOH & 161.0 & 16.0 & 50.43 & 14.8 & 19.06 & 6.49 \\ \hline n-BuOH & 117.0 & 16.1 & 47.05 & 14.9 & 24.07 & 18.63 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of the physical and chemical properties of the alcohols used in the study, as well as the results of thermal and strength testing of L-FDM prints. Figure 12: Feasible reaction of aminopropyltriethoxysilane and PLA [17]. the flow of inert gas. The heat of fusion was determined from the DSC thermograms for each sample in both cycles. The heat of fusion (\(\Delta H_{m}\)) is determined from the area between the peak contour and the baseline. Knowing \(\Delta H_{m}\), the degree of crystallinity (\(w_{c}\)) can be determined from the formula [18]:  
\[w_{c}=\frac{\Delta H_{m}}{\Delta H_{m}^{0}}\times 100\% \tag{1}\]  
where \(w_{c}\)--degree of crystallinity [%]; \(\Delta H_{m}\)--heat of fusion [J/g]; \(\Delta H_{m}^{0}\)--heat of fusion of 100% crystalline polymer (\(w_{c}\) = 100%) [J/g]  
Based on literature data, \(\Delta H_{m}^{0}\) for neat PLA is 93.6 J/g [19]. The crystallinity of neat PLA and PLA modified with different alcohols (Figure 13A) and silanes/siloxanes (Figure 13B) was analyzed using the DSC method. The results showed higher crystallinity in the first heating cycle, which can be attributed to the thermal history and reorganization of polymer structures [20; 21; 22]. During the printing process, residual internal stresses on the unit structure may be present in the polymer, which are often released during the first heating cycle and affect the reorganization of the polymer structure. Additionally, the heating process can affect the spatial arrangement of polymer molecules and establish the rules and principles of the structure, affecting the degree of crystallinity--taking into account the fact that the degree of crystallinity depends on the type of material in the matrix. In the L-FDM technology, the addition of alcohol or solutions of silanes and siloxanes changed the degree of crystallinity. Literature data indicate that in PLA/alcohol systems, crystallization in an induced substance (SIC) is possible, caused by sorption and diffusion of alcohol through the polymer [23]. Hydrolysis in an aqueous environment causes some changes in the crystallinity of PLA, which is mainly dependent on the length of the polymer chains. Other parameters affecting the crystallization process include processing conditions, cooling rate, and nucleating factors [24]. Figure 14 shows the DSC curves for the first and second heating cycles. The graphs show three characteristic ranges for semi-crystalline polymers, which correspond to glass transition, crystallization, and melting. The glass transition temperature (T\({}_{g}\)) ranges from 45 \({}^{\circ}\)C to 70 \({}^{\circ}\)C, the cold crystallization temperature (T\({}_{cc}\)) from 100 \({}^{\circ}\)C to 135 \({}^{\circ}\)C, and the melting point is 145-165 \({}^{\circ}\)C.  
Figure 13: Degree of crystallinity of (**A**) PLA/alcohols and (**B**) PLA/alcohol/silanes or siloxanes. Results showed that in the first cycle for all modified results of the cold crystallization test, there was a broad peak.