*2.7. Mechanical Properties*

The mechanical properties of treated tissues were measured by different tests. All the specimens were previously conditioned at least 48 h in a 50% RH chamber.

The puncture resistance test was performed with a universal testing machine model 3365 (Instron, Norwood, MA, USA) equipped with a load cell of 100 N. A penetration probe with a hemispherical tip was used. As reported in the literature, this type of tip showed the highest reproducibility (lowest variability coefficient) on tests performed on paper laminates [74]. The test was performed at 1 mm/min until a complete break of the tissue. For each test, at least seven specimens were measured. As the puncture test was conducted orthogonally with respect to the surface of the tissues, the eventual orientation of the fibre did not influence the test.

Other mechanical tests were performed on specimens cut in two perpendicular ways, namely cross direction (CD) and machine direction (MD). The tissue was ripped by hand in the two directions. The direction where the rip had a straight progression was called the machine direction (MD), while the direction where the rip went through a deviation was called the cross direction (CD).

The Elmendorf tear test was performed with an Elmendorf tearing tester model 275A (Mesdan-lab, Raffa di Pugenago, Italy) equipped with a 1600 g pendulum, according to BS EN ISO 13937-1:2000 Standard. Specimens were cut with a manual scissor with the help of a jig according to the shape and dimensions reported in the Standard. A pre-notch was performed with the appropriate blade on the instrument. For each test, at least four specimens were measured.

A trouser test was conducted with a universal testing machine model 3365 (Instron, Norwood, MA, USA) equipped with a load cell of 100 N according to ASTM D1938 Standard with a grip-separation speed of 250 mm/min. Specimens were prepared with a manual scissor using a 45◦ blade from the top of the pre-crack to the bottom of trousers, achieving legs dimensions of 65 mm × 12.5 mm and an uncracked area of 25 mm × 25 mm. For each test, at least five specimens were measured.

The tensile test was conducted with a universal testing machine model 3365 (Instron, Norwood, MA, USA) equipped with a load cell of 100 N according to ASTM D882 Standard with a grip-separation speed of 10 mm/min. Tests were performed on ISO 527-2/5A dumbbell specimens obtained with a Manual Cutting Press EP 08 (Elastocon, Brahmult, Sweden). For each test, at least five specimens were measured.

The analysed samples are reported in Table 1.


**Table 1.** Samples studied by mechanical tests.
