Modifications of microfiber synthetic leather base (MSLB) to enhance the sanitary performances: a review

Microfiber leather is a type of synthetic leather made up of a high-grade polyurethane resin and microfiber bundles that resemble the microscopic characteristics of natural leather. Microfiber has benefited from its smaller diameter, which is similar to that of real leather fibrils. Microfibers have received a lot of focus and are frequently employed in the synthetic leather basis, which is an important factor in regulating synthetic leather functionality. Microfiber synthetic leather has advantages over natural leather in terms of mechanical behavior, for example. However, there is a significant difference between natural leather and microfiber synthetic leather in terms of other aspects, such as hygiene issues. Microfiber synthetic leather, unlike natural leather, has inferior transmission and absorption qualities, making it feel hotter. As a result, there is a pressing need to improve the sanitary performance of superfine synthetic leather. Several studies have endeavored to improve the hygienic qualities of MSLB by modifying it in various ways. It is attempted to make a review on the different types of modifications in brief.

Preparation and absorption performance of CNTs/PUR honeycomb composite absorbing material

In this paper, a carbon nanotubes/polyurethane resin (CNTs/PUR) honeycomb composite absorbing material was prepared, and the influence of the content of carbon nanotubes on the absorbing performance of single-layer and double-layer honeycomb composite absorbing materials was investigated. The mechanical properties of single-layer and double-layer materials are discussed. The honeycomb core and carbon nanotubes are compounded together by the impregnation method to form a CNTs/PUR honeycomb composite absorbing material. The microstructure shows that the carbon nanotubes are uniformly dispersed in the water-based polyurethane resin, and the impregnated layer and the honeycomb wall are well combined. The reflectivity of the material shows that as the content of carbon nanotubes increases, the absorption performance of the material first increases and then decreases; when the content of carbon nanotubes is 5.6%, the single-layer honeycomb composite absorbing material has the best absorption performance. The effective absorption bandwidth is 10.6 GHz (2~18GHz), and the maximum absorption strength is -24.5 dB; when the combination mode is 2-4, the double-layer honeycomb composite absorbing material has good absorption performance, and the maximum absorbing strength is -32.2dB, the bandwidth is 13.7GHz (2~18GHz).

Soil Injection Technology Using an Expandable Polyurethane Resin: A Review

The soil injection, using an expandable polyurethane resin, holds a unique potential for settlement compensation, lifting, and strengthening the foundations of existing buildings and structures. Although various research and case studies regarding this technology have been published, these studies emphasized the technology’s effectiveness in the rapid lifting process. Nevertheless, there is no complete understanding of the technology, yet, that gathers necessary data leading to a better recognition for this technology in the theoretical understanding and the practical applications. This article aims to provide a comprehensive understanding of this technology. The injection process, the resin’s mechanism, and actual propagation in the soil’s massive, the modified physic-mechanical properties of the soil, the expansion process, the consumption of the resin, and the durability are extensively reviewed in this article. Besides that, this article aims to demonstrate the advantages and limitations of this technology in practical applications. The review also explores the existing finite element models used to calculate the strength and stiffness parameters, evaluating the bearing capacity of the composite (soil-resin) and the settlement after the injection process.

High-Density Fiberboard from Wood and Keratin Fibers: Physical and Mechanical Properties

Background: High-density fiberboards (HDF) are widely used as a substitute for solid wood in furniture, cabinet, construction materials, etc. Wood fibers are often used in the production of HDF but the use of renewable materials has gained worldwide interest brought about by global pressure to pursue sustainable development. An abundant source of renewable fibers that can be used to produce HDF is keratin from waste chicken feathers. The goal of the study is to investigate the use of keratin fibers in combination with wood fibers to produce HDF. No or limited studies have been conducted in this area and if successful, it could offer an alternative utilization for the billions of kilograms of waste feather produced by the poultry industry. HDF is a high volume feather utilization that can reduce pollution and help solve solid waste disposal problems in many countries. Methods: A series of dry-formed HDFs containing varying ratios of wood and keratin fibers bonded by polyurethane resin were produced. The physical and mechanical properties of the HDFs were determined. Results : The properties of the HDFs were affected by varying ratios of wood particles and keratin fibers. Dimensional stability as indicated by low levels of thickness swelling (<4.6%) and water absorption (<10%) was observed. Internal bond (2.47 MPa), MOE (5.8 GPa) and MOR (45 MPa) values were higher or comparable to those reported in the literature. Conclusion: HDF formed using a combination of wood and keratin fibers bonded together by polyurethane resin to as much as 50% keratin fibers were dimensionally stable with stiffness and strength above the minimum requirements for general use HDF as prescribed by EN 622-5.

Experimental and Numerical Study of Ballistic Resistance of Composites Based on Sandwich Metallic Foams

In recent years, hybrid composite materials are of increasing interest during the search for new materials to be used as ballistic barriers (shields) and kinetic energy absorbers. The main objective of this study is to test the energy absorption capacity of Zn-Al alloys filled with various polymer materials (epoxy resin, polyurethane resin and silicone). The ballistic resistance of modern hybrid materials to direct firing of a 5.56 × 45 mm SS109 projectile and during quasi-static piercing test is examined. Next, a numerical simulation in the ABAQUS environment is performed. In order to accurately reproduce the foam structure, a computed microtomography (CT) system is used. In the simulation of deformations of viscoplastic bodies, the Lagrange and Smoothed Particle Hydrodynamic (SPH) methods are applied. The obtained results from numerical analyses are verified with experimental results. Metallic foams are proven to have only a remote influence on the impact load, while, when filled with polyurethane resin, they show resistance to the overshoot. Performed simulation supports the detailed analysis of the impact energy dissipation for each of the samples.

Use of Specially Treated Hazardous Waste as Filler in Polymer Coatings

The objective of presented research was to verify and evaluate whether the treated hazardous waste (HW) can be used as filler in polymer coatings based on epoxy (EP) and polyurethane resin (PUR). The end product created by the incineration of municipal waste and cement dusts from cement kiln bypasses were chosen for solidification. The hazardous waste used was solidified by a homogenisation method using filter fly ash from fluidized bed combustion of lignite and silica flour as the solidifying agents. The aim was to use as much hazardous waste as possible and incorporate it into the polymer matrix of the coatings. The usability of the filler prepared in this way was verified by testing the tensile properties of polymer coatings, the surface hardness and the adhesion to the concrete. The cohesion of the coatings with concrete was observed using a digital optical microscope. It has been found that the PUR-based coatings with HW content show better properties than the coatings containing only the silica flour as a filler.