## 3 Results and Discussion
In the first heating cycle (Figure 8a), strong relaxation of the polymer can be seen after the injection process in each case. Performing the degradation by UV irradiation led to the destruction of the polymer structure, as can be seen when comparing the graphs for PLA and PLA_UV. During the second heating cycle (Figure 8b), a significant reduction in processing-induced relaxation and significant exothermic peaks can be observed from cold crystallisation. These are more pronounced for samples with added natural fibres, which can thus be considered to be the centres of crystallisation. Due to the different characteristics of the methods, the glass transition temperatures obtained from DMA are higher than the corresponding temperatures from DSC (the PLA_UV sample in DMA was destroyed before the result could be obtained). In the second heating cycle, the glass transition occurred at lower temperatures, and the lowest values were obtained for the samples after UV degradation. The calculated degree of crystallinity of the pure PLA was 54%, and the presence of fibres reduced its value. The melting temperatures are very close to each other, but lower values were obtained for samples with the addition of fibres, especially wool. A reduction in T\({}_{\text{g}}\) values due to the addition of natural fibres has also been noted in other studies. Furthermore, the authors observed that the addition of flax increases the enthalpy of the cold crystallisation of PLA [17]. In the study, the addition of kenaf fibres lowered the melting temperatures of PLA-based composites and accelerated the recrystallisation process [38]. For various plant-based natural fibres, e.g., coir and bamboo, an increase in T\({}_{\text{g}}\) values can be seen in relation to pure PLA [36,37]. The presence of natural fibres in PLA composites mainly affects the degree of crystallinity of the polymer and its properties during processing; furthermore, a significant reduction in the parameters studied after degradation processes confirms its successful course. Selected SEM microphotographs are shown in Figure 9. The SEM observations for pure PLA show very clear cracks for the exposed composite. The appearance of the sample \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Sample** & **T\({}_{\text{g}\_\text{DMA}}\)** (\({}^{\circ}\)C)** & **T\({}_{\text{g}\_\text{DSC1}}\)** (\({}^{\circ}\)C)** & **X\({}_{\text{cl}}\)** & **T\({}_{\text{m1}}\)** (\({}^{\circ}\)C)** & **T\({}_{\text{g}\_\text{DSC2}}\)** (\({}^{\circ}\)C)** & **X\({}_{\text{c2}}\)** & **T\({}_{\text{m2}}\)** (\({}^{\circ}\)C)** \\ \hline PLA & 74 & 67 & 55\% & 177 & 60 & 54\% & 175 \\ L10 & 75 & 64 & 48\% & 177 & 60 & 49\% & 174 \\ W10 & 72 & 65 & 50\% & 176 & 59 & 49\% & 173 \\ PLA\_UV & - & 64 & 52\% & 172 & 58 & 55\% & 172 \\ L10\_UV & 76 & 64 & 31\% & 175 & 54 & 41\% & 172 \\ W10\_UV & 80 & 68 & 46\% & 175 & 59 & 46\% & 172 \\ PLA\_CO & 74 & 65 & 57\% & 176 & 60 & 56\% & 174 \\ L10\_CO & 73 & 67 & 51\% & 177 & 59 & 49\% & 174 \\ W10\_CO & 78 & 67 & 49\% & 175 & 59 & 48\% & 173 \\ \hline \hline \end{tabular}  
* T\({}_{\text{g}\_\text{DMA}}\)—glass transition temperature obtained from DMA; T\({}_{\text{g}\_\text{DSC1}(Q)}\)—glass transition temperature obtained from DSC (1: 1 st heating cycle; 2: 2 nd heating cycle); X\({}_{\text{cl}}\)—crystallinity degree (1: 1 st heating cycle; 2: 2 nd heating cycle); T\({}_{\text{m1}}\)(2)—melting temperature obtained from DSC (1: 1 st heating cycle; 2: 2 nd heating cycle).  
\end{table} 
Table 4: Results * of T\({}_{\text{g}}\) from DMA, DSC analysis and crystallinity in 1 st and 2 nd heating cycle. Figure 8: DSC curves of PLA/natural fibre composites: (**a**) first heating cycle and (**b**) second heating cycle. after composting is not significantly different from that of the sample immediately after fabrication. Figure 9d,g provide a very good comparison of the size and surface area of plant and animal fibres.