## 2 Materials and Methods  
Two species of film were used: film manufactured with 100% recycled material (100 rLDPE/0 LDPE) denoted as RF (recycled film) and without the addition of recycled material (0 rLDPE/100 LDPE) denoted as NRF (non-recycled film). The shrink film is made of rLDPE. The films were produced from used film packaging. Pre-preparation included cutting into pieces (scraps) with a dimension of about 5 mm and drying for 20 h at 75 \({}^{\circ}\)C. The films under study were made using the vertical blow extrusion technique. The film production line included the following modules: Extruder W25/30D (Metalchem Company, Giliwice, Poland), crosshead, air blowing device, flattening, and receiving device. The applied temperatures of the plastification system in specific zones were as follows: 160 \({}^{\circ}\)C--in the feed zone, 180 \({}^{\circ}\)C--in the transformation zone, and 190 \({}^{\circ}\)C--in the dispensing zone. From the extracted granulate, a film of about thickness of 0.05 mm was produced, which was used for testing (manufacturer of films: Polish company). Specimens with a width of 15 and a length of 150 mm were prepared for testing, which were then cut in the longitudinal and transverse directions to the film extrusion direction. To evaluate the mechanical properties of the tested recycled polyethylene film, a static tensile test was conducted. The test was carried out on a TIRAtest 27025 tensile testing machine in accordance with Polish Standards: PN-EN ISO 527-1:2020 [28] and PN-EN ISO 527-3:2019-01 [29]. Next, the tear resistance of the test film samples was determined. For this purpose, a test was carried out using the Elmendorf method in accordance with the Polish standard PN-EN ISO 6383-2:2005 [30]. The machine used was the Pro Tear Tearing Tester, Twing-Albert Instrument Company, New Berlin, NJ, USA. The specimens used in the test were cut longitudinally and transversely to the direction of film extrusion according to a fixed radius template with a 20 mm long notch. The film samples prepared in this way were subjected to a tearing force, which was induced by the energy stored in a 1600 g pendulum. Impact resistance tests were also performed in accordance with Polish standard PN-EN14477:2005 [31]. Tester Dart Drop Impact (Thwing-Albert Instrument Company, USA) was used for the examination. During the test, 200 \(\times\) 210 mm film samples were used. The samples were placed in the clamping head on both sides. A weight in the form of a spearhead was then dropped onto the sample from a height of 660 mm. The weight of the spearhead was increased by 5 g in each successive test. The weight of the spearhead was taken as the impact resistance, for which 50% of the tested samples in the series were destroyed [32,33]. The tests also compared the free shrinkage of the tested film samples. Sample shrinkage testing was performed in accordance with ASTM D2732 [34]. Samples with dimensions of 100 \(\times\) 100 mm were immersed in silicone oil at a temperature of 140 \({}^{\circ}\)C for 10 s. After the film cooled down, the linear dimensions of the samples were measured. In the next step, the film samples tested were subjected to Differential Scanning Calorimetry DSC analysis, which evaluated changes in the physical properties of the polymers with controlled increases and decreases in temperature. Apparatus Thermal Analysis System TGA 2 (Mettler-Toledo company, Columbus, OH, USA, www.mt.com) [35] was used to perform this test. The tests were performed in accordance with the Polish standard ISO 11357-3:199 [36]. The obtained results of the performance properties of the film were compared with those of the polyethylene film without the addition of recycled materials. The properties of this material are shown in Table 1.  
The next step was to conduct an environmental analysis of the process of bulk packaging of bottles using recycled film. To compare the impact of changing the film on the harmfulness of the process, the same amount of energy and film was used in both tested variants.