Research On Comparing Tibetan Pulu Fabrics' Heat & Moisture Transfer Performance And Testing Methods

The heat and moisture transfer performance of fabrics is an important parameter related to human body comfort. In a long time, most related studies are mainly concentrated on the general fabrics, very few about Tibetan costume or fabrics. In recent years, people become to pay more and more attention on the Tibetan costume, but there are very few studies about the heat and moisture transfer performance of their costume or fabrics.For knowing the heat and moisture transfer properties of the Tibetan costume or fabrics better, this article respectively has measured the thermal and moisture permeability properties about 6 types of Tibetan traditonal manual PuLu fabrics and 24 types of general fabrics which include cotton, liner, silk, wool fabrics with the plat-plate warmth retention testing and three types of permeability dish methods. The main contents are as follows1. Tibetan PuLu fabrics' thermal resistance, which is used to characterize the insulating performance, is higher than the general fabrics'. After the correlation analysis of thermal resistance and several factors, the results show that the thermal resistance and thickness have a positive relationship, while thermal resistance is also affeted by the weight, total tight degree, bulk density and so on. Overall, the change rule between Tibetan PuLu fabrics'thermal resistance and the affecting factors is almost the same as the general fabrics'.2. The moisture permeability of Tibetan PuLu fabrics is the lowest among the selected fabric After the correlation analysis of the WVT(Water-Vapor Transimission Rate) and the affecting factors, it is concluded that the overall WVT and the weight have a negative relationship. At the same time, the special weaving process has made that there is a grease over the surface of Tibetan PuLu fabrics, which reduces the moisture vapor transmission performance in a certain extent and also makes the correlation between Tibetan PuLu fabrics and the affecting factors is not significant.3. Combined the analysis of the insulating and moisture permeability properties of the fabrics, we can know that the insulation property of the Tibetan PuLu fabrics is better than general fabrics while the moisture permeability performance is relatively worse.4. After comparing of the three permeability test methods, we can know that the differences of test conditions, test time, etc. cause the great difference about the WVT datas of the three methods. After the Grey relational analysis of the WVT of the three methods and the affecting factors, the results show that the bulk density is the biggest influence factor to affect the mositure permeability, then in order there are density, air permeability rate, total tight degree, weight, thermal resistance and thickness, while the results of the three methods are consistent. In the meanwhile, the first method is greatest affected by the overall eight factors. And the first method is biggest influenced by the bulk density while the third method is inluenced biggest by the density.5. According to the moisture permeability datas of the fabrics measured by the third method, this paper paints the curves of moisture permeability changes over time about fabrics and reference fabrics, finding that fabric or a reference fabric moisture vapor transmission amount over time linearly increases. The angle between the two curves is recorded as Aa, named moisture resistance angle. Trough the analysis and comparation of Aa and the existing index, the results show that we can use the moisture resistance angleΔαto characterize and evaluate the moisture vapor transmission performance of fabrics.