| Author: | Shahzad, Amir |
| Title: | Study of liquid and moisture management properties of fabrics by using a novel sweating simulator |
| Advisors: | Fan, Jintu (SFT) |
| Degree: | Ph.D. |
| Year: | 2023 |
| Subject: | Moisture in textiles Textile fabrics -- Technological innovations Textile fabrics -- Physiological aspects Hong Kong Polytechnic University -- Dissertations |
| Department: | School of Fashion and Textiles |
| Pages: | xvii, 148 pages : color illustrations |
| Language: | English |
| Abstract: | This research is aimed at investigating the liquid and moisture management properties of fabrics under profuse sweating conditions. The research consists of two parts: (i) the development of a sweating simulator to determine the amount of sweat accumulated in as well as evaporated and dripped from the fabric when subjected to continuous sweating, and (ii) the development of fibrovascular capillary bed moisture management fabrics for use under profuse sweating conditions. The fabric function of real-time personal sweat management may involve liquid absorption, spreading, evaporation, dripping, and drying occurring simultaneously. However, the concurrent and real-time measurements of these fabric properties under the conditions representing the actual end-use conditions have been a great challenge. The commonly used bench-scale instruments generally lack the true replication of fabric-perspiring skin interaction, simulated skin and sweat temperatures as well as changing body posture. This research presented an advanced instrument, a novel sweating simulator (NSS), for concurrent and real-time assessment of fabric liquid and moisture management at a simulated skin and sweat temperature, in an inclined upright orientation, and under continuous sweating. NSS comprises a sweating plane with a regional sweating zone located in the upper middle region to simulate a person's upper-back sweating zone. The temperatures of the sweating plane and sweat were adjustable to simulate the skin and sweat temperature of a sweating human body. Eight different kinds of knitted fabrics were tested on NSS to validate the accuracy, reproducibility, and capability of NSS in differentiating the fabrics. On the NSS, liquid and moisture management properties were evaluated by the simultaneous and real-time measurement of liquid accumulation, evaporation, dripping, and drying with three calibrated measuring balances. The tests consisted of a sweating phase followed by a drying phase, each lasting one hour. The fabrics were tested on NSS twice; first, the temperature of the sweating plane and sweat was set to room temperature, and then it was regulated to a body's simulated skin and sweat temperature. NSS demonstrated excellent reproducibility and measurement accuracy in evaluating and differentiating the fabrics under different testing conditions. The measurement accuracy ranged from 98% to 100%, with most tests exceeded 99%. In addition, using the temperature sensors embedded on the sweating plane, NSS measured the upward, lateral, and downward flow rates of liquid through the fabrics at the constant rate of liquid supplied. Experiments revealed that some fabrics showing excellent capillary flow could not sustain the downflow rate of liquid through fabric against the increasing liquid content under continuous sweating. A stage is arrived when the liquid flow is accelerated through fabric in downward direction under the prevailing influence of gravitation force in upright orientation of NSS. While some fabrics demonstrated superior potential for sustaining the downflow rate throughout the entire sweating phase. Because evaluating fabric liquid and moisture management in terms of liquid accumulation, evaporation, dripping, drying, and variation of capillary flow rate along the gravitational direction at increasing liquid content has practical implications, NSS's comprehensive testing capability can be extremely useful in the design and development of next-generation liquid and moisture management fabrics for clothing and various industrial applications. Furthermore, the interrelationships between NSS test results of liquid mass distribution for both non-temperature-controlled NSS and temperature-controlled NSS and conventional wicking tests were investigated. During the sweating phase, the liquid evaporation, accumulation and discharge were found to be negligibly correlated with the rate of vertical wicking. However, the rate of horizontal wicking was found to be strongly positively and significantly correlated with the liquid evaporation during sweating phase, only at temperature-controlled NSS. The quick absorption, wicking and evaporation of sweat by the next-to-skin fabrics play an indispensable role in personal wet-thermal management. However, when subjected to the bulk of sweat from profuse sweating, conventional moisture management fabrics that focus on liquid quick absorption, fast spreading, and evaporation may become heavier, sticky, odorous, and uncomfortable. In cases of extreme sweating, sweat dripping from fabric may also occur. Therefore, effective liquid sweat management by conventional textiles has been challenging in extreme sweating conditions. Herein, to address the limitations of conventional moisture management fabrics in profuse sweating, we report a cardiovascular capillary bed-inspired fibrovascular capillary bed design to regulate the bulk flow of sweat accumulated in the fabric from sweating skin. We designed and fabricated fibrovascular capillary bed (FVCB) networks by laser cutting a conventional moisture management fabric. The FVCB networks demonstrated a significant reduction in liquid accumulation, an increase in liquid transmission and discharge, and an improvement in area-specific liquid evaporation and drying efficiencies when compared to a plain specimen of the same fabric. Additionally, the feasibility of creating a FVCB network on a conventional moisture management fabric was also investigated using the spray finishing method. When compared to the conventional fabric substrate, the FVCB-treated fabric showed a 42% reduction in liquid accumulation, a 20% increase in liquid discharge, about 50% increase in area-specific liquid evaporation but only a slight decrease of about 6.0% in the absolute mass of liquid evaporation. Besides, sweat drained, instead of dripping inappropriately on the floor, was able to be collected at the end of sideways branches of FVCB network. Because of the promising liquid moisture management potential of FVCB networks, this work offers insight into the design and development of futuristic garments for enhanced personal comfort in sweaty conditions. |
| Rights: | All rights reserved |
| Access: | open access |
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