Michał Sąsiadek

This paper presents the results of experimental tests on the static tensile strength and relative elongation of three-layer films containing varying proportions of recycled polyethylene and subjected to an embossing process. Films containing varying proportions of recycled low-density and high-density polyethylene were produced by blown film extrusion. The embossing process was carried out under varying processing conditions, and embossing patterns with different geometrical characteristics were produced on the three-layer films under investigation. The films were manufactured and the experimental tests were conducted under industrial conditions. Based on the results obtained, the effects of three different embossing pattern geometries and the embossing process parameters on the tensile strength of three-layer films made from recycled polyethylene were evaluated in the machine and transverse directions. The experimental results enabled the identification of embossing pattern geometries and recycled polyethylene contents that increased static tensile strength in selected material–process combinations. No statistically significant improvement in elongation at break was confirmed compared with the non-embossed reference films. The findings are limited to static tensile strength and elongation at break in the machine direction (MD) and cross direction (CD), which contribute to improving certain functional properties of refuse bags, specifically ensuring adequate load-bearing capacity for the waste they contain.

Environmental protection in sheet-metal manufacturing requires decisions that limit avoidable material consumption, waste generation and resource-intensive processing. This study presents a calibrated simulation model for resource-efficient manufacturing of an Innovative Dispatch-Receiving-Organisational System (ISNOO), a high-mix sheet-metal product. The model connects manufacturing optimisation with environmental performance through sheet nesting, overproduction avoidance, machine-state timing, buffer control and transport planning. It covers 11 production units, buffers, transport, three product variants and stochastic disturbances. A representative comparison of nesting and scheduling alternatives reduced the reported completion time from 1.33 to 1.07 days (19.5%). Shop-floor measurements were collected for a plan of 20 units per variant and an adjusted plan of 6 units per variant. Mean capability indices across eligible operation-product records were Cp = 1.142 and Cpk = 1.036 in the first campaign, and Cp = 1.615 and Cpk = 1.402 in the second. These differences reflect different production schedules and record sets; calibration improved the model representation but does not indicate improved physical process capability. The model identifies opportunities to prevent unnecessary sheet-metal processing, reduce potential scrap and rework, and convert idle-ready periods into planned shutdowns. Because direct material-loss, energy, and emission measurements were unavailable, these outcomes are proxies for resource efficiency and potential environmental benefits rather than quantified reductions in waste or greenhouse-gas emissions.

This study developed and implemented, under industrial conditions, a multi-criteria procedure for evaluating three-layer polyethylene films with a high regranulate content. A set of validated production formulations with varying secondary-material content was investigated. The methodology compared five mechanical properties with predefined, group-specific performance thresholds and used a non-compensatory Q index to express relative functional compliance; regranulate content was considered separately as an indicator of secondary-material use. Pareto front analysis was used to identify optimal material variants by considering the relationship between recycled content and their relative compliance with the applicable group-specific requirements. The proposed approach supports screening the functional properties of manufactured film products (high-strength refuse bags) at elevated recycled-material content levels.

Deposit return systems (DRS) can increase the capture of beverage packaging, but material circularity is not determined by return rate alone. A returned container contributes to high-value circularity only if it passes recognition, sorting, pre-processing, and material-specific quality gates. This article evaluates the material-quality performance of three returned beverage-packaging materials—polyethylene terephthalate (PET), aluminium and reusable glass—using a quality-gated high-value recovery framework. The model defines a high-quality recovery index, HQR = R × Q × Y, where R is the return rate, Q is the quality factor of the returned stream, and Y is the reprocessing or reuse yield. The HQR indicator describes the quality of the entire DRS process. The core purpose of the HQR model is to distinguish nominal packaging return from high-quality material recovery and to show whether returned PET, aluminium and reusable glass streams remain suitable for high-value circular pathways. A survey-supported early-stage return scenario (R = 0.50) is compared with the 77% and 90% separate-collection targets used in European policy. To strengthen the PET branch of the model, a pilot PET stream-quality and processing-yield dataset was incorporated, including PET purity, colour composition, non-PET impurities, residual moisture, organic residues, intrinsic viscosity, washed PET flake or pellet yield, and sorting/washing rejection. The pilot data indicate that Lithuania had higher PET quality (98.2% PET purity, 80% clear PET, 1.8% non-PET impurities, IV = 0.74 dL/g, and 84.5% washed PET yield) than the Polish regional average (94.3% PET purity, 72.7% clear PET, 5.7% non-PET impurities, IV = 0.721 dL/g, and 80.3% washed PET yield). At R = 0.50, the pilot-derived PET HQR is approximately 37.8% for Lithuania and 31.6% for the Polish regional average. The results indicate that the same nominal return rate can lead to substantially different high-quality recovery outcomes because PET is constrained by stream purity, colour, contamination, and processing yield; aluminium by alloy and remelting control; and reusable glass by inspection, breakage, and refill compatibility. The proposed framework can support structured DRS operator reporting by identifying the material-quality and yield variables that should be measured alongside mass collection; however, operator-level validation is required before the model can be used as a predictive performance tool.

The governing system of equations for the model of a locally inhomogeneous elastic body is based on constitutive equations generalized to account for local inhomogeneity of the binding energy and includes an equation for the mass density in the form of an inhomogeneous Helmholtz equation. This paper shows that, by selecting appropriate mass sources (the inhomogeneous term in the mass density equation), it is possible to obtain a mass density distribution in the near-surface region that reflects the characteristics of the Abbott–Firestone curve, which is widely used in engineering practice to describe surface roughness. Using a flat surface as an example, the influence of the model parameters on the core, peak, and valley zones of the material ratio curve is investigated. When modeling the influence of the surface roughness parameters of a real body on the effective elastic moduli of thin films, it is assumed that the local Young’s modulus and Poisson’s ratio are functions of the mass density. The solution to the problem for a stretched layer is expressed in quadratures, and its analysis is performed using numerical methods. In particular, it is shown that the characteristic length scales of the size effects of the effective elastic moduli depend on the structural heterogeneity of the material and on the sizes of the core, peak, and valley zones of the roughness profile.

Industrial drying of spunlace nonwovens (fibrous materials produced by hydroentanglement using high-pressure water jets) represents one of the most energy-intensive stages of production due to the high water content remaining after the hydroentanglement process and the large thermal energy required for water evaporation. Understanding the relationship between material structure, production parameters, and water removal intensity is therefore essential for improving process efficiency. This study investigates the drying behavior of viscose–polyester spunlace nonwovens using an integrated mass balance and statistical modeling approach based on industrial production data. Process parameters were collected from an industrial SCADA (Supervisory Control and Data Acquisition) monitoring system and combined with laboratory measurements of nonwoven mass per unit area. Experimental results show that 926–1840 kg/h of water can be removed during drying at temperatures below 100 °C, depending primarily on production speed and structural parameters of the material. A multivariate exponential regression model was developed to describe the nonlinear relationship between drying temperature, production parameters, and water removal intensity. The model demonstrated high predictive accuracy when validated with independent test data. The results indicate that mass throughput and structural characteristics dominate the drying process, while temperature variations remain limited by technological constraints. The proposed modeling framework enables predictive control of industrial drying conditions and provides a practical tool for improving energy efficiency in industrial nonwoven manufacturing.

Viscose–polyester nonwovens are now widely used. The desired performance properties of these nonwovens, such as quality and strength, depend to a large extent on the carding process, in which homogenised layers of properly mixed fibres are formed. In this article, a comparative analysis of two different designs of modern, double-drum carders and their impact on the quality of fibre mixing and on the strength of the final nonwoven fabric is presented, based on research and tests carried out in an industrial production line. To this end, mathematical models were developed for the relevant indicators (fibre delay time and the average fibre circulation path length in the carding machine) that characterise the carding process. Based on numerical calculations, these indicators were determined for the actual geometry of the carding elements and the process parameters applied in the tests. A discussion is provided to interpret the values of these indicators and their correlation with the strength of the nonwoven fabric produced, taking into account the different design of the carders used in the tests. The results showed that the average fibre delay time ranged from 1.40 s to 1.99 s, while the corresponding fibre delay length varied between 4.42 m and 6.30 m. Moreover, the mean fibre circulation path length was greater in the second carding machine (20.5–26.4 m) than in the first (16.9–17.0 m), indicating more intensive longitudinal fibre mixing.

This work concerns the experimental verification of changes in the energy efficiency of photovoltaic installations through the use of bifacial modules. For this purpose, an experimental stand was designed and built for the comparative analysis of the efficiency of two types of photovoltaic panels: bifacial (bPV) and monofacial (mPV). The tests consisted of placing the panels at different heights above the ground surface and at different angles. During the tests, three substrates with different albedo were taken into account: green grass, gray concrete (fabric), and white snow (polystyrene). The tests for both types of panels were carried out simultaneously (in parallel), which guaranteed the same environmental conditions (temperature and solar radiation intensity). Based on the results of the voltage and current measurements for different angles of PV module inclination and, for bPV panels, different heights above the ground surface and different types of substrate, a series of current–voltage characteristics and power characteristics were plotted. The “additional” energy efficiency of bifacial panels compared to monofacial panels was also determined. It was shown that under favorable conditions, using bifacial panels instead of monofacial panels can increase the production of electricity by more than 56% from structures of the same dimensions. The research results can be of great value when designing photovoltaic installations.

The article presents the results of experimental studies on selected, mechanical properties of three-layer film, produced by blown film extrusion. Three-layer film was developed for making garbage bags. The research was carried out under industrial conditions. The three-layer film sleeves tested...