Thermal Conductivity Test Of Fiber Assembly Materials And Its Applications For Materials Design

Thermal conductivity is an important indicator reflecting on the thermal performance of fiber assembly.Several defects has been conceived with the equipments and the corresponding calculation formula of thermal conductivity,especially for the case of the thickness of fiber above several millimeters.For solving this problem,Professor Wang and Dr.Cui made addictives to the original KES-THERMO ? thermo-physical properties test system to form an improved apparatus and derived a new calculation formula for porous materials,especially for the case of fibrous porous materials.Then we investigate the effect of the improved devices and new calculation formula compared with original ones.With the new test method,we studied the thermal properities of wadding under different temperatures,and optimized its structure.The main contents and conclusions are as follows:(1)Through series of tests,it is proved that the testing results became more accurate after improvement.Based on seepage mechanics of porous materials for the case of fibrous porous materials,thermal conductivity calculated by the new formula was scientific and reasonable,eliminating some abnormal phenomenon frequently occurred on the original equipment,such as"a thicker sample usually has a higher thermal conductivity".And it is found that the new calculation formula is fit for woven fabric,knitted fabric,non-woven felt-like material and unconventional textile materials with approximately uniform structure.(2)Wadding plays a key role in cold protective clothing.Kapok/down fiber blended wadding and pure down wadding were used as the object.By the improved test devices and newly calculation formula,the experimental relationship between the different thickness of wadding and its thermal conductivity under the different mechanical load was acquired.According to the distribution laws of a multi-layers clothing system,the relationship between the engineering thickness of wadding and its heat resistance was obtained.Finally the formula between the surface density of wadding and its heat resistance was established.A quick and easy method for determining the surface density of wadding under different temperatures to maintain human thermal comfort was proposed,which was considered on the human body metabolic heat production rate and the national standards about maintaining human thermal comfort.(3)Wind is anther major environmental factor affecting the cold resistance of cold protective clothing.The thermal effect of cold protective clothing of different configuration was investigated by heat emission under the low wind speeds as well as permeability under the high wind speeds.Under the low wind speed,the cold resistance of detachable clothing was slightly better than that of the ordinary ones,and when the surface density of wadding used in the ordinary clothing doubled,its cold resistance was almost not affected by the wind speed.The clothing sample filled with yak hair fiber wadding had the top cold resistance among the other five filled with different animal wadding.Under high wind speed,the clothing filled with kapok/down fiber blended wadding and yak hair fiber wadding had better performance,and the wind resistance of samples with quilting was worse than any other samples which were processed uniformly.Coated fabric had good wind resistance performance,and coating almost had no effect on its heat conduction.