PSI - Issue 64

Rosario Lombardi et al. / Procedia Structural Integrity 64 (2024) 1919–1926 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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3. Results and Analysis 3.1. Physical Characterization

3.1.1. Density The obtained results in terms of yarns density are summarized in Figure 2.

Figure 2 – Density of coated natural yarns

As can be observed, the overall density of the yarns does not vary significantly as the deposited PLA varies also in comparison with the reference (REF) uncoated samples. This is probably due to the fact that both materials, fabric and polymer, have a similar density compared to each other. An important information concerns the impregnation carried out on the "pieces" of fabric described previously is the following: it was possible to notice how, for high viscosities, the meshes of the impregnated fabrics are completely "sealed" by the polymer. In particular, this happens for: Flax (125 g/m 2 ) impregnated with a ratio of 85/15 and 90/10; Flax (265 g/m 2 ) impregnated with 85/15 ratio; Jute (320 g/m 2 ) impregnated with 85/15 and 90/10 ratio. 3.1.2. Linear density (dried and undried specimens) As already clarified in the previous section, the value of the linear density was determined in two different conditions for the yarns: dried and undried samples. As can be seen in Figure 3, the value of the linear density decreases as the acetone-PLA ratio considered decreases: this is congruent with the fact that as the PLA value considered in the ratio increases, the viscosity of the solution increases, and therefore the quantity of biopolymer filed.

Figure 3 – Linear density (undried and dried) of coated natural yarns

Furthermore, the measurement of linear density in the dried and undried conditions highlights that the TEX und value is always higher than the TEX dry , due to the quantity of water absorbed from the surrounding environment. Furthermore, it is possible to notice how this increase is more accentuated for an acetone-PLA ratio in favor of the polymer, an this is more evident in the case of Jute 320 g/m 2 . As it was possible to observe during the creation of the samples, this can be associated to the configuration of the jute yarn, which is more "frayed" compared to flax, and