In this study, poly(vinyl-alcohol) (PVA)/chitosan (CS) polymer blend films with different amounts of CS (0, 5, 20 and 35 wt. %) crosslinked by glutaraldehyde (GA) were prepared. The structure and properties of the prepared polymer films were studied by means of dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and the time-lag permeation technique. The DMA analysis showed that CS reduces the crystallinity degree of PVA, leading to a higher amount of the amorphous phase contributing to the α relaxation that corresponds to the glass-to-rubber transition. However, the mobility of the amorphous phase can be restricted with crosslinking with 1 wt. % GA. Interaction between the PVA and the CS was confirmed by DCS analysis. Additionally, the influence of the CS and crosslinking on the permeation of nitrogen molecules was investigated. The permeation was examined by the time-lag method. It was found that the addition of CS and GA to PVA improves barrier properties.

Jarosite is a by-product of the zinc manufacturing industry. The potential use of jarosite processing waste as a component in hybrid composites offers a valuable opportunity for addressing waste management and environmental challenges. Therefore, in this study, hybrid composites were prepared using a polyester matrix reinforced with five layers of a fiberglass chopped strand mat and incorporating 5, 10, and 15 wt.% of jarosite waste particles as fillers. The hand lay-up technique was used for the composite preparation, with jarosite particles pre-dispersed in the polyester resin by an ultrasonic probe treatment to ensure the uniform dispersion of the jarosite particles within the matrix. The flexural properties (the flexural strength, modulus, and apparent interlaminar shear strength), Charpy impact strength, and hardness of the composites were determined and analyzed. The results showed that adding 10 wt.% of jarosite significantly improved the flexural strength (30% higher than the base composite) and hardness (15% higher). Composites with 5 wt.% and 15 wt.% of jarosite showed similar properties to the base composite. These findings demonstrate the potential of jarosite waste as a sustainable filler in hybrid composites, balancing mechanical properties and sustainability.

In the context of quality management and Industry 5.0, reproducibility is a critical indicator of the ability to achieve consistent and predictable results in laboratories, research, as well as in systems and processes. Reproducibility is also an indispensable component of measurement uncertainty, which quantifies the precision of measurement results. To standardize the measurement procedure for surface topography parameters obtained using atomic force microscope (AFM) and to establish the accuracy and precision of measurement results, an analysis of repeatability and reproducibility was conducted in accordance with the ISO 5725-2:2019 standard, Accuracy (trueness and precision) of measurement methods and results – Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method. Measurements were performed on two AFM standards and a steel sample. The research was conducted over the course of one year and repeated after four years using the same samples.