Study On Formation And Properties Of Down Web Based On The Colligation Of Warp Knitting

Thin, flexible, light quality and high efficient heat resistant is the target of the heat resistant material. Particularly these several items must be satisfied in the meantime when the materials are used in spaceflight, national defense and even special civil situation. Because the material chosen as thin, flexible and light thermal resistant material mainly is fiber material, the best choice may be down which meets the requirement. Therefore, the theory and method of formation of down web must be solved before the realization of the stable down sheep structure. The research on its formation and the relation method, equipment and properties of down web based on the colligation of warp knitting are carried out in the paper for solving the key problem in its formation.Firstly according to the theory of Gauss, the calculation of thermal resistance and the structure model, which was built by previous researcher, were analyzed and discussed. It showed that there is relationship between thermal conduction and inner structure of down web. Considering volume changes caused by press, the bulky property was discussed according the single fiber compression bending model. So it was found that press can increase the heat transmit paths so that reducing the thermal resistance. However, the other effect of press is that the heat resistance caused by touching is increased. Therefore both influences, which are caused by press, should be considered in the research of heat resistant properties.Secondly, down was chosen to be the material as the middle layer. After analyzing the composite technology presently, the method of spun-lace was considered to be the suitable technology. Colligation experiments were carried out. In this experiment process the basic requirements were solved, which included the single down control during making a layer and the strain control when transporting the web.Thirdly, the spun-lace equipment for the experiment was designed by our team. This equipment had several functions: by controlling the stress in all directions, web kept a stable movement on the flat surface; by using electromagnetic valve and gas source, the discontinuous punching caused by water was achieved; the down feeding amount and the speed of web movement were made to fit together effectively by means of changing the rotate speed of gear; the equipment was controlled by computer system, on which the experiment parameter can be adjusted. Now the equipment is filing an application for a patent.Finally, the down web material was tested on the basic properties. The aim of the thickness measurements was to evaluate the fastness of down web. By analyzing the thickness changes of down web, the stability of material was proved. Then down and wool were tested on the compression bending analyzer （FiCBA）. According to the test results, it was found that down was softer than wool. The equivalent bending modulus of down was 0.785GPa and flexural rigidity was 1.78×10^-5cNcm². By test and calculation the value of elastic properties after compression was 90.9% and 75.79cm³/g. Down web had a good mechanical properties. The tensile force in the two directions was not the same. One was 60N, the other was 22.3N. The thermal resistance was also tested, which was 23.3. By analysis these experiments provided the data for the properties of down web.The establishment of model, chose of material, the design of formation method and equipment and measurement for properties are the main content of the paper. Down web based on the colligation of warp knitting has been realized as a kind of thin, flexible and light thermal resistant material. The research has also provided a new method for the application of down material.