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Abstract

The research was focused on the heating capacity of developed, isolated from water penetration, knitted textile heating element with incorporated conductive silver (Ag)- plated yarns, which can be used in manufacturing heating textile products intended for recreation, sports, or health care for elderly. The aim of the investigation was to obtain an appropriate temperature on a human skin, generated by the textile heating element surface at a lower voltage depending on a variety of wearing conditions indoor. Depending on the supplied voltage to the heating element, an incoming electric energy can be converted into different heat. Therefore, the electrical and achieved temperature parameters of heating elements are very important by selecting and adapting required power source devices and by setting the logical parameters of programmable controllers. The heating–cooling dynamic process of developed textile heating element was investigated at different simulated wearing conditions on a standard sweating hot plate and on a human skin at applied voltages of 3V and 5V. It was discovered that a voltage of 5 V is too big for textile heating elements, because the reached steady state temperature increases to approximately 39–40°C, which is too hot for contact with the human skin. The voltage of 3 V is the most suitable to work properly and continuously, i.e., to switch on when the adjusted temperature is too low and to turn off when the necessary temperature is reached. Based on the values of reached steady-state heating temperature, the influence of the applied voltage, ambient air flow velocity, and heating efficiency, depending on various layering of clothes, was determined. Recorded temperatures on the external surface of the heating element provided the possibility to assess its heat loss outgoing into the environment. It was suggested that heat loss can be reduced by increasing thermal insulation properties of the outer layer of the heating element or using layered clothing. On the basis of the resulted heating characteristics, recommended parameters of power source necessary for wearable textile heating element were defined.

Abstract

The objective of this study is to investigate the morphological (scanning electron microscopicy images), thermal (differential scanning calorimetry), and electrical (conductivity) properties and to carry out compositional analysis (Fourier-transform infrared) of produced nonwoven fibrous materials adapted in biomedical applications as scaffolds. The orientation of produced nanofilaments was also investigated because it is considered as one of the essential features of a perfect tissue scaffold. Viscosity and electrical conductivity of solutions, used in the manufacturing process, were also disassembled because these properties highly influence the morphological properties of produced nanofibers. The nanofibrous scaffolds were fabricated via conventional electrospinning technique from biopolymer, synthetic polymer, and their blends. The chitosan (CS) was chosen as biopolymer and polyethylene oxide (PEO) of low molecular weight as synthetic polymer. Solutions from pure CS were unspinnable: beads instead of nanofibers were formed via spinning. The fabrication of pure PEO nanomats from solutions of 10 wt%, 15 wt%, and 20 wt% concentrations (in distilled water) turned out to be successful. The blending of composed CS solutions with PEO ones in ratios of 1:1 optimized the parameters of electrospinning process and provided the opportunity to fabricate CS/PEO blends nanofibers. The concentration of acetic acid (AA) used to dissolve CS finely spuninned the nanofibers from blended solutions and influenced the rate of crystallization of manufactured fiber mats. The concentration of PEO in solutions as well as viscosity of solutions also influenced the diameter and orientation of formed nanofibers. The beadless, highly oriented, and defect-free nanofibers from CS/PEO solutions with the highest concentration of PEO were successfully electrospinned. By varying the concentrations of AA and low molecular weight PEO, it is possible to fabricate beadless and highly oriented nanofiber scaffolds, which freely can found a place in medical applications.