The submitted paper deals with the physical and mechanical properties of geopolymer composite materials reinforced with natural fibres. For this study, we aimed to develop a geopolymer composite reinforced with long flax fibres, which were implemented in the geopolymer in the form of a nonwoven fabric that reinforced the structure of the geopolymer over the entire thickness of the board. In order to compare the properties of the developed composite with natural fibres, a geopolymer without fibres and a geopolymer reinforced with basalt fibres were also produced. The monitored mechanical properties were impact bending, bending strength and compressive strength. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and microscopic analysis were also carried out. The results clearly showed the positive effect of the addition of natural fibres on impact bending and bending strength. However, the addition of natural fibres in the form of a nonwoven fabric significantly increased the variability of the properties of the developed composites. In addition, a different pattern of joint failure was noted between geopolymer reinforced with flax fibres and geopolymer reinforced with basalt fibres.

Bending rigidity is a significant property of textiles that influences their further behavior, for example draping and wrinkling. The thorough analysis of draping and wrinkling behavior of textiles requires also knowledge of bending rigidity of the textiles in different directions, the so-called anisotropy of bending rigidity. Anisotropy of bending rigidity has been so far mostly measured on rectangular shaped samples; nevertheless, the circular shape seems to be the ideal one. This article presents device TH-7, which enables one to measure this non-standard circular shaped sample. Comparing the results of measuring of bending rigidity on the standard device KES-FB2 with the results of measuring on device TH-7, we can see a very good correspondence, that is, the value of the correlation coefficient equals 0.9. The described way of measuring the anisotropy of bending rigidity on circular samples will speed up and improve the quality of further research in the field of influence of the textile structure (weave, sett) on bending rigidity and, consequently, on draping and wrinkling of the textile.

The development of composite materials from alternative raw materials, and the design of their properties for the intended purpose is an integral part of the rational management of raw materials and waste recycling. The submitted paper comprehensively assesses the physical and mechanical properties of sandwich composite material made from particles of winter rapeseed stalks, geopolymer and reinforcing basalt lattices. The developed composite panel is designed for use as a filler in constructions (building or building joinery). The observed properties were: bending characteristics, internal bonding, thermal conductivity coefficient and combustion characteristics. The results showed that the density of the particleboard has a significant effect on the resulting mechanical properties of the entire sandwich panel. On the contrary, the density of the second layer of the sandwich panel, geopolymer, did not have the same influence on its mechanical properties as the density of the particleboard. The basalt fibre reinforcement lattice positively affected the mechanical properties of sandwich composites only if it was sufficiently embedded in the structure of the particle board. All of the manufactured sandwich composites resisted flame for more than 13 min and the fire resistance was positively affected by the density of the geopolymer layer.

This paper deals with the development and characteristics of the properties of a permeable water-resistant heat insulation panel based on recycled materials. The insulation panel consists of a thermal insulation core of recycled soft polyurethane foam and winter wheat husk, a layer of geopolymer that gives the entire sandwich composite strength and fire resistance, and a nanofibrous membrane that permits water vapor permeability, but not water in liquid form. The observed properties are the thermal conductivity coefficient, volumetric heat capacity, fire resistance, resistance to long-term exposure of a water column, and the tensile strength perpendicular to the plane of the board. The results showed that while the addition of husk to the thermal insulation core does not significantly impair its thermal insulation properties, the tensile strength perpendicular to the plane of these boards was impaired by the addition of husk. The geopolymer layer increased the fire resistance of the panel for up to 13 min, and the implementation of the nanofibrous membrane resulted in a water flow of 154 cm² in the amount of 486 g of water per 24 h at a water column height of 0.8 m.

Creasing is one of the most important properties of textiles for apparel application. Most fabrics are regularly evaluated by means of etalons, that is, visual standards. Nevertheless, due to the disadvantages of visual evaluation, which is unreliable and time consuming, several objective methods were developed. In this article, a new objective method of multidirectional evaluation of creasing is described. We have proposed the test method of angle recovery using image processing. The specimen of the fabric was of a circular shape and it was measured by the method of angle recovery in various directions. We compared the results obtained from our method with the method described by Sommer and by the hollow cylinder method also. We found good conformity between the results obtained from our method and the method described by Sommer.

There are many indoor and outdoor areas where one encounters acoustic discomfort. In this study, the design possibilities of a passive acoustic panel with macro-openings are investigated. An acoustic panel which absorbs a defined frequency of sound can be created when a suitable combination of acoustic absorption affecting parameters is found. These optimum parameters for a panel with macro holes were sought by means of experimental research regarding: the type of raw material suitable for the production of the components of the acoustic panel, the optimal hole shapes, their size and positioning on the panel lid, the possibility of using shredded textile from unsorted textile waste. The experiments in which the influence of the hole size and placement on the acoustic absorption was investigated were verified using a theoretical electrical equivalent circuit model created in the MathCad programming environment. The study found that the commonly used perforated panels made of Plexiglas can be fully replaced by panels made of shredded unsorted textile waste. It has also been shown that the shapes of the holes which can act as a design element can have various combinations, i.e. as long as the same percentage of perforation is maintained, the size of the circular holes or the shape of the slotted holes do not matter, as their acoustic absorption is within approximately the same range. The findings published in the study can help in the design of passive panels for both interiors and exterior use.