3.5.1. Puncture Resistance Test

The puncture resistance of coated and uncoated tissues was determined by measuring the force needed to penetrate the paper with a blunt probe and its maximum deflection before breakage. This test can be used as a simple and quick preliminary study to predict the mechanical properties of nonwoven fabrics under quasi-static deformation [79–81].

In Figure 9a, differences between the force needed to penetrate treated and untreated tissues are shown. It was clear that the application technique strongly influenced the mechanical properties of the tissue. In fact, the sample treated with water (TW) showed a maximum force that was almost doubled with respect to the untreated tissue (TP). As a result, treated tissues should then be compared with this tissue and not with the untreated one. Considering treated tissues, TA appeared to be more easily penetrable compared to TW, while TC showed a similar behaviour.

**Figure 9.** Maximum force (**a**) and maximum deflection (**b**) that tissues can sustain before breakage. Significance of standard deviation was investigated with a Tukey HSD post hoc test performed on 7 different specimens. On the top of each column, a letter was reported. Means that were identified as not significantly different were grouped under the same letter.

Maximum deflection values of tissues reported in Figure 9b represent the maximum displacement of the probe before tissues breakage. Nonsignificant differences between TP, TW, and TC values were observed.

In general, all measured values were similar except for TC that showed a maximum deflection slightly higher compared to the other samples. This behaviour could be compatible with the formation of a more compact structure thanks to the chitin nanofibrils presence that can sustain a greater deflection and force. The analysis of variance of the mean maximum force (Figure 9a) evidenced a significant difference between TC with respect to TA or the pure tissue, confirming its effect on reducing the penetrability of the coated tissue. Conversely, the analysis of mean maximum deflection (Figure 9b) showed a significant negative effect of TA with respect to the other samples, reducing the maximum deflection before breakage of the tissue.
