## 3 Results and Discussion
It can be seen that PLA homogenised much better with the flax fibres, covered them, and formed a physical bond over a significant area of the fibre. In Figure 9e,h, it can also be seen that both the fibres and the matrix have been degraded, but in Figure 9f,i, it can be seen that the main degrading component are the fibres. Broken fibres and pulling out of fibres from the matrix (pull-out) have also been observed by other scientists studying similar biocomposites [18; 20]. They have reached similar conclusions, noting that the higher the content of natural fibres in the biocomposite, the worse the degradation that occurs [24]. Additionally, EDS studies were performed on the samples, which confirmed the qualitative composition of the composites tested. For the pure PLA and L20 samples, peaks were obtained for carbon and oxygen. For the W20 composites, peaks were obtained for carbon, oxygen, nitrogen, and sulphur. Surface microscopic observations of the samples after and before degradation were carried out to assess the visual effects of the degree of degradation--Figure 10.  
Figure 9: SEM images of samples: (**a**) PLA; (**b**) PLA_UV; (**c**) PLA_CO; (**d**) W20; (**e**) W20_UV; (**f**) W20_CO; (**g**) L20; (**h**) L20_UV; and (**i**) L20_CO. When comparing samples made from PLA alone (Figure 10a-c), clear cracks can be seen for the samples degraded under UV radiation. They have also lost their transparency. The composted PLA sample shows slight wrinkling on the surface, which may indicate the beginning of surface degradation, but apart from this, there is little difference from the non-degraded PLA. For the samples in group W10 (Figure 10d-f), a clear difference can be seen between the degraded samples and the samples after generation. The degraded samples are much lighter in colour, with uneven surfaces and protruding fibre fragments visible. It is caused by the appearance of microcracks in the volume of the PLA sample, on which the passing light disperses, giving the sample a milky discolouration effect. The composted W10 sample shows deep cracks and significant distortion of the whole sample. The brightest (milky) fragments on the edges and around the fibres signal that biodegradation is taking place mainly on the surface and in the adjacent fibres due to their high hygroscopicity. The degraded W20 samples, like the W10 samples, differed significantly in colour from the undegraded sample. Degradation progresses along the fibres. This is likely due to the easy absorption of water in the volume of wool fibres, and in a humid environment, it is easier to degrade the PLA matrix. The L10 samples (Figure 10g-i), as the wool fibre samples, changed colour after degradation to a lighter colour. In the literature, similar observations can be found; the presence of moisture in the environment accelerates the degradation process of biocomposites. The fibres transport moisture into the interior of the sample, causing them to swell. This phenomenon speeds up the degradation [18; 19]. A difference can be seen between the type of degradation of the two samples (Figure 10h,i): the composted sample shows white traces arranged mainly along the fibres and smooth brown areas of the matrix, while on the UV-illuminated sample, the degradation is more uniform throughout the composite. In the  
Figure 10: PLA and composite surface observed under a digital microscope (50\(\times\) magnification): (**a**) PLA; (**b**) PLA_UV; (**c**) PLA_CO; (**d**) W10; (**e**) W10_UV; (**f**) W10_CO; (**g**) L10; (**h**) L10_UV; and (**i**) L10_CO. L20 samples, the colour change in the sample during the degradation test was comparable to the samples in the L10 category.