fibrous materials
Recently Published Documents

AbstractFibrous materials are among those most used for the thermal and acoustic insulation of building envelopes and are also suitable for a wide range of applications. In building construction, the demand for products with low environmental impact — in line with the Green Deal challenge of the European Community — is growing, but the building market is still mostly oriented towards traditional products, missing the many opportunities for using waste materials from existing industrial production. The paper presents the experimental results of new thermal and acoustic insulation products for building construction and interior design, based on previous experiences of the research group. They are produced entirely using waste sheep’s wool as a “matrix” and other waste fibres as “fillers”. The materials proposed originate from textile and agri-industrial chains in the Piedmont region and have no uses other than waste-to-heat biomass. The panels have characteristics of rigidity, workability, and thermal conductivity that make them suitable for building envelope insulation.

Biosourced materials such as vegetal wools offer major thermal insulation advantages in the green buildings field. Experimental characterisations of vegetal wools thermal conductivity as a function of their density show the existence of an optimum conduction-radiation coupled value. This specific point, as well as the properties of vegetal wools are related to the large variability of shapes and sizes of their fibres. In order to take this specificity into account, it seems particularly relevant to use micro-macro modelling methods to predict the thermal conductivities related to both conduction and radiation heat transfer phenomena. In a first time, a self-consistent method based on a cylindrical geometry (SCMcyl) is used as a modelling approach for conduction transfers. Then, a modelling approach developed by Bankvall and based on an equivalent fibre radius value is used for radiation transfers. So, by coupling these two approaches, it is possible to obtain an equivalent thermal conductivity of fibrous materials as a function of density. Finally, this method is validated by comparison with experimental data.

Abstract. The paper presents the results of determining the sorption properties of nonwoven materials modified with clay minerals, obtained on the basis of fibrous waste, in relation to the methylene blue indicator to determine the possibility of using the created materials in the purification of light industry wastewater from dyes and heavy metal ions.Purpose. Determination of kinetic regularities of sorption (by methylene blue) of fibrous nonwoven materials modified with different types and amounts of clay adsorbents.Methodology. Nonwovens obtained from elastic fibrous waste of the textile industry were used as a basis in the work. They consisted of Lycra 162 C (PU) complex fibers and Nylon 6.6 f20 / 1 (PA-6.6) fibers in a ratio of 70/30 wt. %. For bonding the nonwoven material, adhesive bicomponent fibers Acebon 4/51 black (4 den) (BVCh) (20 wt%) were added to the initial composition. To enhance the sorption capacity of the PU / PA / BV 80/20 fabric, powders of montmorillonite clay (clay grade PBA-18) and palygorskite (clay grade PP-5) type were introduced in an amount of up to 40% by weight of the nonwoven material. Evaluation of the sorption properties of modified fibrous materials with different clay adsorbents was performed by determining the change in the optical density of MS solutions of a given concentration.Scientific novelty. It was found that fibrous materials modified by the studied samples of montmorillonite and paligorskite clays show high absorption capacity relative to the methylene blue dye due to its multilayer sorption. After 24 hours of processing, the degree of absorption is 70% when using clay brand PBA-18 in the amount of 40% by weight of the fibrous material, which is higher than when using clay brand PP-5 (45%) under the same conditions.Practical value. Sorption materials modified with clay minerals can be further used to treat wastewater from light and chemical industries from heavy metal ions.

While the toxicity of metal-based nanoparticles (NP) has been investigated in an increasing number of studies, little is known about metal-based fibrous materials, so-called nanowires (NWs). Within the present study, the physico-chemical properties of particulate and fibrous nanomaterials based on Cu, CuO, Ni, and Ag as well as TiO2 and CeO2 NP were characterized and compared with respect to abiotic metal ion release in different physiologically relevant media as well as acellular reactivity. While none of the materials was soluble at neutral pH in artificial alveolar fluid (AAF), Cu, CuO, and Ni-based materials displayed distinct dissolution under the acidic conditions found in artificial lysosomal fluids (ALF and PSF). Subsequently, four different cell lines were applied to compare cytotoxicity as well as intracellular metal ion release in the cytoplasm and nucleus. Both cytotoxicity and bioavailability reflected the acellular dissolution rates in physiological lysosomal media (pH 4.5); only Ag-based materials showed no or very low acellular solubility, but pronounced intracellular bioavailability and cytotoxicity, leading to particularly high concentrations in the nucleus. In conclusion, in spite of some quantitative differences, the intracellular bioavailability as well as toxicity is mostly driven by the respective metal and is less modulated by the shape of the respective NP or NW.

Three ceramic fibrous materials of the Al2O3-SiO2 system with different densities have been treated using concentrated solar radiation. The experiment was performed using technological capabilities of the Big Solar Furnace in the 2 modes: the first mode includes heating up to 1400–1600 °C, holding for 1.5–2 h; the second mode (the fusion mode) includes heating up to 1750–1900 °C until the sample destruction, which is accompanied by fusion. Upon completion of the experiment, the phase composition, microstructure, and compressive strength of the materials were studied. It was shown that the investigated materials retained their fibrous structure under prolonged treatment in the first mode up to temperatures of 1600 °C. The phase composition of the ceramic materials changes during the experiment, and with a decrease in the density, the modification is more pronounced. Treatment of all three materials under study in the fusion mode resulted in the formation of the eutectic component in the form of spherulites. The compressive strength of the materials was found to be slightly reduced after exposure to concentrated solar radiation.

It has long been known that materials containing cellulose fibers in their composition are destroyed by molds, microorganisms, actinomycetes, which use cellulose as a carbon source. Different fibrous materials to varying degrees (but always) are affected by molds. It is known that linseed and cotton types of paper are affected by the smallest number of fungi, and sulphate ones by the largest. The most biostable is cotton paper, the composition of which contains chalk in a sufficiently large amount. The observations carried out by the authors showed that the highest biostability (fungal resistance) is characteristic of papers containing chalk and kaolin, the lowest is glued types of paper with a high degree of sizing. Aging of paper with increasing temperature increases the overall susceptibility of all types of paper tested without exception. Obviously, changes in the physical and chemical properties of paper as a result of aging create more favorable conditions for the growth of fungi. It is well known that paper can serve as a medium for the spread of infectious diseases. The authors of the article studied the thermo-physical properties of basalt fiber and investigated the possibility of using it for the manufacture of heat-insulating technical paper.Obtaining materials that are not affected by bacteria, insects and molds (fungicidal,insecticidal) can be solved by using inorganic fibers, which are obtained from almost unlimited natural resources and which have excellent biochemical properties. It should be noted that the concept of "biocidal" paper (material) is collective. It combines species that differ in their ability to kill bacteria (bactericidal), molds (fungicidal), insects (insecticidal). Each of the biocidal types of materials has two or more of these properties.

Currently, the significantly developing fields of tissue engineering related to the fabrication of polymer-based materials that possess microenvironments suitable to provide cell attachment and promote cell differentiation and proliferation involve various materials and approaches. Biomimicking approach in tissue engineering is aimed at the development of a highly biocompatible and bioactive material that would most accurately imitate the structural features of the native extracellular matrix consisting of specially arranged fibrous constructions. For this reason, the present research is devoted to the discussion of promising fibrous materials for bone tissue regeneration obtained by electrospinning techniques. In this brief review, we focus on the recently presented natural and synthetic polymers, as well as their combinations with each other and with bioactive inorganic incorporations in order to form composite electrospun scaffolds. The application of several electrospinning techniques in relation to a number of polymers is touched upon. Additionally, the efficiency of nanofibrous composite materials intended for use in bone tissue engineering is discussed based on biological activity and physiochemical characteristics.

Ukrainian enterprises annually generate millions cubic meters of mineralized water, which is discharged into surface reservoirs, and millions cubic meters of highly concentrated solutions and suspensions, which are accumulated and stored in special sludge storages. This waste water causes irreparable damage to the environment. A new method for the evaporation of industrial concentrates by fibrous materials with capillary properties was proposed not so long ago. The use of such materials allows an effective, autonomous, cheap, and extremely simple system to be created for the evaporation for various liquids and concentrates. The research methodology was as follows. Two graduated cylinders of the same diameter were used in our research. One cylinder was filled with the liquid phase to a certain level and used to control evaporation from the surface of the aqueous medium. In the other, experimental cylinder, a vertical cotton strip was additionally placed (from 1 to 21 layers of fabric). The width of the strip was 5 cm. The length of the strip was 50 cm. The density of cotton was 100 g/m2. The research method was to determine the height of liquid phase capillary rise along the strip of fabric and to evaluate reduction in the volume of liquid that evaporates in both cylinders at set temperatures. It was found that in the absence of wind and the distance between the vertically placed strips of 7–15 mm were sufficient to ensure the maximum evaporation intensity. Our long-term experiments in natural conditions confirmed the high efficiency of the proposed method. At an average daily air temperature of 2.3 °C, there was a significant evaporation from the surface of the fabric during the day. In this case, evaporation from the water surface was not observed. It should be noted that the intensity of evaporation under natural conditions depends on a significant number of factors (temperature, wind speed, luminosity, humidity, etc.), so it is difficult to detect a direct relationship between some of them. With increase only in the liquid phase temperature, the evaporation efficiency decreased. At a temperature of 20 °C, the laboratory installation (15 layers of cotton strip) increased the evaporation intensity by more than 2 times, at 46 °C by more than 5 times, at 57 °C by almost 3 times, but at 75 °C only by about 67 %. It is obvious that heating of the liquid phase alone less influences the evaporation process from the surface of the fabric strip, which was cooled rapidly in the atmosphere at a much lower temperature. Therefore, to increase the evaporation intensity, it is necessary to increase temperature for all components of the liquid–fabric system. A fabric with suitable properties, stretched between two metal racks and immersed into the liquid phase with the lower end, can be used as a simple evaporator. Our research has shown that the use of materials with capillary properties in the treatment of liquid solutions allows simple, cheap, and efficient devices to be created for evaporating water and converting liquid waste into a solid phase.

Atherosclerosis (AS), one of the most common types of cardiovascular disease, has initially been attributed to the accumulation of fats and fibrous materials. However, more and more researchers regarded it as a chronic inflammatory disease nowadays. Infective disease, such as periodontitis, is related to the risk of atherosclerosis. Porphyromonas gingivalis (P. gingivalis), one of the most common bacteria in stomatology, is usually discovered in atherosclerotic plaque in patients. Furthermore, it was reported that P. gingivalis can promote the progression of atherosclerosis. Elucidating the underlying mechanisms of P. gingivalis in atherosclerosis attracted attention, which is thought to be crucial to the therapy of atherosclerosis. Nevertheless, the pathogenesis of atherosclerosis is much complicated, and many kinds of cells participate in it. By summarizing existing studies, we find that P. gingivalis can influence the function of many cells in atherosclerosis. It can induce the dysfunction of endothelium, promote the formation of foam cells as well as the proliferation and calcification of vascular smooth muscle cells, and lead to the imbalance of regulatory T cells (Tregs) and T helper (Th) cells, ultimately promoting the occurrence and development of atherosclerosis. This article summarizes the specific mechanism of atherosclerosis caused by P. gingivalis. It sorts out the interaction between P. gingivalis and AS-related cells, which provides a new perspective for us to prevent or slow down the occurrence and development of AS by inhibiting periodontal pathogens.

To deal with issues of process sustainability, cost, and efficiency, we developed materials reengineered from fibers to serve as super-bridging agents, adsorbents, and ballast media. These sustainable fiber-based materials considerably increased the floc size (~6630 µm) compared to conventional physicochemical treatment using a coagulant and a flocculant (~520 µm). The materials also reduced coagulant usage (up to 40%) and flocculant usage (up to 60%). These materials could be used in synergy with coagulants and flocculants to improve settling in existing water treatment processes and allow facilities to reduce their capital and operating costs as well as their environmental footprint. Moreover, the super-sized flocs produced using fiber-based materials (up to ~13 times larger compared to conventional treatment) enabled easy floc removal by screening, eliminating the need for a settling tank, a large and costly process unit. The materials can be effective solutions at removing classical (e.g., natural organic matter (NOM) and phosphorus) and emerging contaminants (e.g., microplastics and nanoplastics). Due to their large size, Si- and Fe-grafted fiber-based materials can be easily recovered from sludge and reused multiple times.