Study On Thermal Comfort Of Hydroscopic And Quick-dry Sportswear

With more and more attention being paid to the comfort of clothing, especially clothing’s thermal comfort during exercise, hydroscopic and quick-dry fabrics came into being and have been widely used in sportswear. More and more kinds of hydroscopic and quick-dry fabrics are being developed due to advanced chemical technology and textile science. Compared with traditional sportswear, whether or not hydroscopic and quick-dry sportswear can improve wearer’s thermal comfort during exercise is not sure yet because of few and insufficient studies conducted already. Therefore, a study on thermal comfort of hydroscopic and quick-dry sportswear was carried out and presented in this thesis.Four typical knitted fabrics for sportswear(cotton, blend of cotton and polyester, polyester, hydroscopic polyester) were made into four tight-fit sportswear(code: CS, CPS, PS, HPS) and a loose sportswear made of hydroscopic polyester fabric(code: HPSL). The study was conducted in three aspects: Firstly, the measurement of sportswear thermal insulation in the static and dynamic(It、Itr); Secondly, the measurement of sportswear evaporative resistance in the static and dynamic(Ret、Retr); Thirdly, performance test with manikin wearing different sportswear imitating a process of 40-min exercise of various intensity(4.5 METs or 6.5 METs) and 20-min rest(1 MET) under two environment conditions(22℃,65%RH;30℃,70%RH) respectively, and the average skin temperature(Tsk), core temperature(Thy) and sweating rate(Sw) were observed. All tests were completed on the manikin Newton. Because evaporative resistance is an important parameter for sportswear’s thermal comfort and the manikin must be covered with a fabric ―skin‖ to create a wet surface during test, using different ―skin‖ fabrics might cause different results of Ret measurement. So before measuring the Ret of sportswear, the effect of manikin ―skin‖ fabric on measuring clothing evaporative resistance was investigated. The Ret of sportswear was then measured with a suggested ―skin‖ from the ―skin‖ fabric study.The results indicate that:(1) Manikin ―skin‖ fabric does affect the measurement of clothing Ret. When a skin made of water-absorbing fabric like cotton was used, the Ret of the same clothing was lower and clothing, especially tight-fit clothing, got wet easier than using a cotton/polyester skin or polyester skin, which could change clothing Ret. Therefore, a synthetic fabric was suggested for the manikin ―skin‖.(2) Fabric components have little effect on sportswear thermal insulation but significant effect on its evaporative resistance. The rank order of sportswear Ret from high to low is CS, CPS, PS and HPS.(3) In the dynamic, both clothing thermal insulation and evaporative resistance were lower than those in the static. The Itr was lower than It by about 26% while the Retr of different sportswear was lower than Ret by different levels: it was 19% for CS, CPS and PS, and 25% for HPS and HPSL.(4) During performance tests, increasing the air temperature or adding exercise intensity would increase heat stress to human body. When the air temperature was increased to 30℃ from 22℃ and the exercise intensity was added to 6.5 METs from 4.5 METs, the body Tsk, Thy and Sw after exercise could be higher by 2.92℃, 0.96℃ and 18.68 g/min respectively.(5) When the air temperature was 22 or 30 and doing moderate exercise, body in CS got significantly higher Tsk, Thy and Sw than in CPS, PS and HPS, body in PS and HPS got similar and lowest Tsk, Thy and Sw. However, when doing vigorous exercise under 30℃,body in HPS got significantly lower Tsk, Thy and Sw than in PS. After exercise, the body in HPS got lower Tsk, Thy and Sw than in CS by 0.5 ℃, 0.15 ℃ and 2.22 g/min respectively.(6) Loose hydroscopic and quick-dry sportswear got higher It, Itr(by 11%), Ret(by 24%) and Retr(by 21%) than the tight-fit one. When a vigorous exercise under 30℃ was finished, body in HPSL got higher Tsk, Thy and Sw than in HPS by 0.28℃, 0.1℃ and 2 g/min respectively.It was found that manikin ―skin‖ fabric does affect the measurement of clothing Ret and a synthetic fabric was suggested for the manikin ―skin‖. Fabric components have little effect on sportswear thermal insulation but significant effect on its evaporative resistance. Sportswear made of fabrics with better hydroscopic and quick-dry ability got lower Ret. In the dynamic, Itr was lower than It by about 26% while the Retr of different sportswear was lower than Ret by different levels which could be 25% for HPS and HPSL. Compared with traditional cotton sportswear, hydroscopic and quick-dry sportswear presented significant thermo-physiological benefits for wearers and showed lager benefits when the sweat rate was high. The rank order of sportswear thermal comfort during exercise from high to low is: HPS, PS, CPS CS. Compared with tight-fit sportswear, loose hydroscopic and quick-dry sportswear got higher It, Itr(by 11%), Ret(by 24%), Retr(by 21%), Tsk(by 0.28℃), Thy(by 0.1℃) and Sw(by 2 g/min), which led to lower thermal comfort. Therefore, using hydroscopic and quick-dry fabric like synthetic fabric and tight-fit style can improve thermal comfort of sportswear.