## 3 Results and Discussion
### Characterization of Flax Yarns After Enzymatic Treatment
In the present study, the removal of pectin and hemicellulose components resulted in a decrease in the surface polarity of the flax fabrics, reducing the presence of hydroxyl groups distributed on their surface. Based on these results, Peclyve was chosen as the most effective preparation to modify the surface properties of flax fibres. Therefore, the subsequent enzymatic treatments on flax yarns were performed using this preparation. To analyse in detail the action of the Peclyve solution, different solution concentrations (2.5, 5, 7.5 and 10 wt %) and treatment times (3, 4.5 and 6 h) were investigated. The water drop test, although useful for a qualitative analysis of the wetting behaviour of the different flax fabrics, was characterized by a large data dispersion, hence it proved to be inadequate in identifying a precise relationship between the process times and enzyme concentrations used. The changes in the surface morphology of flax yarns produced by the Peclyve solution were compared with those of the untreated flax yarns. The differences between the surface morphology of neat and modified flax yarns using the Peclyve solution at 5 wt % for 6 h are reported in Figure 2. One of the main effects observed after the enzymatic treatment was the removal of a substantial part of the impurities present on the untreated fibres--such as fat and waxes--that bind the flax bundles together, ensuring good mechanical properties of the yarn [36]. The FE-SEM micrographs reported in Figure 3 show the morphologies of the flax yarns after the different enzymatic treatments. Irrespective of the treatment condition, flax yarn fibrillation and individualization were observed. It is worth highlighting that the longer the process time and the greater the enzyme concentration, the higher the fibrillation of yarns. As reported by [PERSON] et al. [21], pectinase is the enzyme that contributes the most to the separation of fibres from their yarn. An enzymatic effect observed only at high solution concentrations was the progressive breakage of the flax fibres present at the outer surface of the yarn. This effect was found for the yarns treated for 4.5 h and 6 h using a Peclyve concentration of 10 wt % (Figure 4). The modification of the surface chemistry of flax yarns after the biochemical treatments was analyzed by Fourier-Transform Infrared (FT-IR) spectroscopy. To highlight the changes induced by the enzymatic treatment on the composition of the flax yarns, the FT-IR analysis was carried out on the samples treated using the minimum (Figure 5) and maximum (Figure 6) concentration of the Peclyve solution. The spectra appear to be similar, however the main effect produced by the enzymatic treatment was a strong reduction in the bands at around 1736-1742 cm\({}^{-1}\), which can be assigned to the carboxylic ester in the pectin and wax [37] and to the carbonyl C = O stretching of the acetyl groups of hemicellulose [38] and, at 1597 cm\({}^{-1}\), 1514 cm\({}^{-1}\) and 1450 cm\({}^{-1}\), of the lignin [8]. It is to be noted that the enzyme preparation used in the present study was not pure, therefore the presence of side enzyme activities cannot be excluded. The removal of pectin bonded to hemicellulose might have triggered the  
Figure 2: Comparison between the lateral surface of the untreated flax fibres (**A**) and the flax fibres treated with 5 wt % Peclyve for 6 h (**B**). disruption of the network in line with the results in [21], where a reduction in the hemicellulose content in flax and hemp fibres was found after a treatment based only on pectinases (polygalacturonase and pectinmethylesterase). The reduction in the bands for hemicellulose, pectin and lignin was observed for flax yarns treated with both 2.5 wt % and 10 wt % Peclyve solution, thus confirming that the enzymatic treatment was able to successfully degrade hydrophilic substances like hemicellulose and pectin present on the surface of flax yarns.