Search Results (3)

This publication presents the results of research aimed at analyzing the dynamic stretching process of multifilament polyester and polyamide threads with medium linear densities. Building virtual design tools for the mechanical properties of textiles under dynamic impact conditions on their structures is a fundamental challenge for identifying textile technological processes and their behavior in real operating conditions. In the Autodesk^® Inventor^® software environment, a virtual analogue model was built based on appropriately connected modules of the Kelvin–Voigt rheological models, for which the input parameters of the selected rheological models were defined. The nonlinear static and dynamic elasticity coefficients were determined based on the obtained results of experimental tests carried out in static conditions on a testing machine at a speed of 33 × 10⁻⁶ m/s and in dynamic conditions on a constructed measuring device. The nonlinear viscosity coefficient was calculated based on data read from the force-time characteristics obtained by measuring forces during stress relaxation in the threads. To conduct this research, an original research stand was designed and built. A series of simulation calculations of the dynamic stretching process were performed for different values of linear densities, lengths of stretched thread sections, and stretching speeds. A comparative analysis of the characteristics obtained from experimental and modeling studies was performed. A very good agreement between the experimental and numerical simulation curves was obtained, which leads to the conclusion about the usefulness of the tools used in the work for the physical description of the thread stretching process. Full article

The fused deposition modeling (FDM) process, an extrusion-based 3D printing technology, enables the manufacture of complex geometrical elements. This technology employs diverse materials, including thermoplastic polymers and composites as well as recycled resins to encourage sustainable growth. FDM is used in a variety of industrial fields, including automotive, biomedical, and textiles, as a rapid prototyping method to reduce costs and shorten production time, or to develop items with detailed designs and high precision. The main phases of this technology include the feeding of solid filament into a molten chamber, capillary flow of a non-Newtonian fluid through a nozzle, layer deposition on the support base, and layer-to-layer adhesion. The viscoelastic properties of processed materials are essential in each of the FDM steps: (i) predicting the printability of the melted material during FDM extrusion and ensuring a continuous flow across the nozzle; (ii) controlling the deposition process of the molten filament on the print bed and avoiding fast material leakage and loss of precision in the molded part; and (iii) ensuring layer adhesion in the subsequent consolidation phase. Regarding this framework, this work aimed to collect knowledge on FDM extrusion and on different types of rheological properties in order to forecast the performance of thermoplastics. Full article

In recent years, hydrogels have been widely used as drug carriers, especially in the area of protein delivery. The natural silk fibroin produced from cocoons of the Bombyx mori silkworm possesses excellent biocompatibility, significant bioactivity, and biodegradability. Therefore, silk fibroin-based hydrogels are arousing widespread interest in biomedical research. In this study, a process for extracting natural silk fibroin from raw silk textile yarns was established, and three aqueous solutions of silk fibroin with different molecular weight distributions were successfully prepared by controlling the degumming time. Silk fibroin was dispersed in the aqueous solution as “spherical” aggregate particles, and the smaller particles continuously accumulated into large particles. Finally, a silk fibroin hydrogel network was formed. A rheological analysis showed that as the concentration of the silk fibroin hydrogel increased its storage modulus increased significantly. The degradation behavior of silk fibroin hydrogel in different media verified its excellent stability, and the prepared silk fibroin hydrogel had good biocompatibility and an excellent drug-loading capacity. After the protein model drug BSA was loaded, the cumulative drug release within 12 h reached 80%. We hope that these investigations will promote the potential utilities of silk fibroin hydrogels in clinical medicine. Full article