Rigid polyurethane foams were obtained using two types of renewable raw materials: bio-polyols and a cellulose filler (ARBOCEL^® P 4000 X, JRS Rettenmaier, Rosenberg, Germany). A polyurethane system containing 40 wt.% of rapeseed oil-based polyols was modified with the cellulose filler in amounts of 1, 2, and 3 php (per hundred polyols). The cellulose was incorporated into the polyol premix as filler dispersion in a petrochemical polyol made using calenders. The cellulose filler was examined in terms of the degree of crystallinity using the powder X-ray diffraction PXRD -and the presence of bonds by means of the fourier transform infrared spectroscopy FT-IR. It was found that the addition of the cellulose filler increased the number of cells in the foams in both cross-sections—parallel and perpendicular to the direction of the foam growth—while reducing the sizes of those cells. Additionally, the foams had closed cell contents of more than 90% and initial thermal conductivity coefficients of 24.8 mW/m∙K. The insulation materials were dimensionally stable, especially at temperatures close to 0 °C, which qualifies them for use as insulation at low temperatures.

One of the essential factors in prostheses is their fitting. To assemble a prosthesis with the residual limb, so-called liners are used. Liners used currently are criticized by users for their lack of comfort, causing excessive sweating and skin irritation. The objective of the work was to develop viscoelastic polyurethane foams for use in limb prostheses. As part of the work, foams were produced with different isocyanate indexes (0.6–0.9) and water content (1, 2 and 3 php). The produced foams were characterized by scanning electron microscopy, computer microtomography, infrared spectroscopy, thermogravimetry and differential scanning calorimetry. Measurements also included apparent density, recovery time, rebound elasticity, permanent deformation, compressive stress value and sweat absorption. The results were discussed in the context of modifying the foam recipe. The performance properties of the foams, such as recovery time, hardness, resilience and sweat absorption, indicate that foams that will be suitable for prosthetic applications are foams with a water content of 2 php produced with an isocyanate index of 0.8 and 0.9.

The authors of this paper use an original method of diatomaceous earth fractionation, which allows for obtaining a filler with a specific particle size distribution. The method makes it possible to separate small, disintegrated and broken diatom frustules from those which maintained their original form in diatomaceous earth. The study covers a range of tests conducted to prove that such a separated diatomic fraction (3–30 µm) shows features different from the base diatomite (from 1 to above 40 µm) used as an epoxy resin filler. We have examined the mechanical properties of a series of diatomite/resin composites, considering the weight fraction of diatoms and the parameters of the composite production process. The studied composites of Epidian 601 epoxy resin cross-linked with amine-based curing agent Z-1 contained 0 to 70% vol. of diatoms or diatomaceous earth. Samples were produced by being casted into silicone molds in vacuum degassing conditions and, alternatively, without degassing. The results have shown that the size and morphology of the filler based on diatomaceous earth affects mechanical and rheological properties of systems based on epoxy resin. Elongation at rupture and flexural stress at rupture were both raised by up to 35%, and impact strength by up to 25%.

Diatomaceous earth are sediments of unicellular algal skeletons with a well-defined hierarchical structure. Despite many tests conducted on systems using diatomaceous earth and epoxy resins, we can find many differences in the methods of acquisition and characteristics of the composite, which may considerably affect the results. In our study, we have conducted tests to verify the impact of the method of obtaining samples and the degassing of the composite on its mechanical properties and standard deviation. The samples were cast in glass moulds and silicone moulds and then subjected to testing for their mechanical and functional properties, imaging with the use of an optical microscope and a scanning electron microscope. The tests have shown that, for samples cast in glass moulds, there is no heterogeneity within the area of the tested sample, as in the case of samples cast in silicone moulds. Silicone moulds allow for quite effective self-degassing of the resin due to the large area-to-mass ratio, and the small remaining air vesicles have a limited effect on the mechanical properties of the samples. The filler used also played a significant role. For systems containing base and rinsed diatomite, it is clear that the degassing of mixtures increases the tensile strength. For treated diatomite, the elongation at break grew along with increasing filler concentration, while for base diatomite, the improvement was observed for flexural strength and impact strength. A non-modified epoxy resin shows a tensile strength at 19.91 MPa (silicone mould cast). At the same time, the degassed, glass mould-cast systems containing 12% of base and rinsed diatoms showed a tensile strength of 27.4 MPa and 44.7 MPa, respectively. We have also observed that the higher the filler concentration, the higher were the tensile strength values, which for the rinsed diatoms reached over 55.1 MPa and for the base diatoms were maximum of 43.8 MPa. The tests, therefore, constitute a set of guidelines and recommendations for testing with the use of fillers showing an extended inner structure.

The biological methods are considered as environmental-eco-friendly methods for the silver nanocomposites mediation and are widely used in this context. However, the biological methods go along with the relevant limitations, for instance simultaneous synthesis of silver chlorides (AgNCl) type during the AgNPs mediation process. Therefore, the present research is coming to summarize several aspects in this context. Firstly, to present the possible promotion of the sustainable development using bioactive source (e.g. milk) as a source of two different available and new lactobacillus strains (Lactobacillus curvatus and Lactobacillus fermentum). Secondly, to show the ability of the respective isolates to be involved in mediation of various biosilver nanocomposites ((Bio)NCs) synthesis. Moreover, at this stage, for the first time, two (Bio)NCs mediation methods, called “direct method” and “modified method”, have been developed, thus three types (AgNPs, AgNCl and AgNP@AgNCl) of nanocomposites mediated by two different Lactobacillus isolates take place. The interdisciplinary approach included using several spectroscopic, microscopic, spectrometric and thermogravimetric methods demonstrated that all six synthesized nanoparticles (three AgNPs, AgNCl and AgNP@AgNCl types from each source) consist of complex structure including both metallic silver core as well as organic surface deposits. The spectrometric technique allowed to identification of the organics branching surface, naturally secreted by the used Lactobacillus isolates during the inoculation step, suggesting the presence of amino-acids sequences which are direct connected with the reduction of silver ion to metal silver, and subsequently with the formation of coated (Bio)NCs and nucleation process. Moreover, based on the obtained results, the mediation mechanism of each (Bio)NCs has been proposed, suggesting that the formation of AgNPs, AgNCl and AgNP@AgNCl types occurs in different manners with faster synthesis firstly of AgNCl, then of the AgNPs type. No differences between the (Bio)NCs synthesized by two different Lactobacillus isolates have been noticed indicating no discrepancies between metabolites secreted by the respective sources. Graphical abstract

In this investigation, three different explosive materials have been used to improve the properties of titanium grade 2: ammonal, emulsion explosives, and plastic-bonded explosives. In order to establish the influence of explosive hardening on the properties of the treated alloys, tests were conducted, including microhardness testing, microstructure analysis, and tensile and corrosion tests. It has been found that it is possible to achieve a 40% increase in tensile strength using a plastic explosive (PBX) as an explosive material. On the other hand, the impact of the shock wave slightly decreased the corrosion resistance of titanium grade 2. The change in corrosion rate is less than 0.1µm/year, which does not significantly affect the overall corrosion resistance of the material. The reduction in corrosion resistance is probably due to the surface geometry changes as a result of explosive treatment.