With the continuous improvement of living standards, the comfort and functional properties of apparel are highly demanded. Heat produced in the process of exercise, if not released in time, will cause an uncomfortable feeling of stickiness. The heat of human body is mainly released by sweat evaporation and thermal conduction inside and outside fabrics. Therefore, the demand for textiles with the function of moisture absorption and cooling is increased year by year.
However, the speed of sweat evaporation of fabric depends on the interconnection of capillary pores, while the highly efficient internal and external heat conduction requires a compact structure. It indicates that the optimal balance of the two is hard to reach. The currently developed fabrics with comfort give a preference to moisture adsorption and evaporation while ignore the property of heat release, which indicates that the development of textiles with the function of moisture adsorption and cooling is of great significance.
After millions of years of natural evolution, plants are endowed with an optimized mode of water transport and heat release - transpiration, where the plant can obtain the necessary nutrients and water and exchange heat with the external environment through the multi-level bifurcation network of vascular tissue and vein system.
Through comparison, the function of moisture-absorbing and cooling of textiles and the plant transpiration share the same working principle. Plants transport the absorbed underground water through the vascular and vein systems to promote nutrient transfer and water evaporation and avoid the damage of high temperature. Textiles with the function of moisture-absorbing and cooling facilitate the evaporation of sweat produced from skin to cool and dry the human body. Therefore, fibrous membrane with multi-level interconnected network structure optimizes the design of textiles with the function of moisture-absorbing and cooling.
Recently, the Ding Bin research group of Donghua University has successfully developed moisture-absorbing and cooling textiles with multi-level interconnected network structure on the basis of plant transpiration. The fabric is made of PU (polyurethane) /BNNS (boron nitride nanosheet) which are high thermal conductivity oriented fibers, realizing the performance of anti-gravity one-way moisture transfer and efficient heat release by utilizing multi-level bifurcated interconnected pores between fibers.
The one-way moisture transfer rate of the moisture-absorbing and cooling textiles can reach up to 1072% with a moisture evaporation rate of 0.36 g/h. Through the thermal infrared camera, it can be seen clearly that the bionic PU/BNNS fibrous membrane performs better than traditional fabrics in heat conduction under the dry/wet conditions.
In addition, on the basis of optimizing the performance, the moisture transfer and heat release mechanism based on the multi-level interconnected network structure is proposed, providing a theoretical basis for further understanding of the heat and moisture transfer in the multi-level interconnected pores of fibers, and a reference for the design and development of textiles with the function of moisture absorbing and cooling.
The relevant achievement entitled “A Biomimetic Transpiration Textile for Highly Efficient Personal Drying and Cooling" is published in Advanced Functional Materials.
Source: China Textile Leader