Study On The Modification Of Performance Of The Polyurethane (PU) Films And Coated Fabrics By Superfine Wool Powder

This thesis reviewed at first the existing research results of the wool powder and waterproofing and water vapor permeable fabrics. On the basis of former study, we do some research work as follows:A method of physical blending is used to prepare blended films with a kind of superfine wool powder and polyurethane resin. The internal structure and physical-mechanical properties of the films are observed and tested, then use this new kind of blending materials to coat on pure cotton plain clothes. In the end, we compare the influence of blending with two different kinds of powders.Direct dry films are prepared with wool powder and polyurethane through blending preparation. Observations carried out by scanning electronic microscope (SEM) show that wool has good compatibility with polyurethane resin in N, ,/V-dimethylformamide. The wool powders are uniformly distributed in the films, and there is almost no apparent agglomeration. In the X-ray diffraction results of the direct dry films, the height of the X-ray diffraction peak declines gradually with the addition of the wool powder. This indicates that the addition of the lowly polymerized wool powder is relatively easy to increase the amorphous content of the films. Thermogravimetric(TG) analysis shows that with the increase in wool powder content in the blended films, the component of water in the samples enhanced accordingly, furthermore, the initial decomposition temperature of the samples has the trend to decrease. This phenomenon shows the thermal stability of the polyurethane resin falls with the addition of the wool powder. And the dynamic mechanical analysis (DMA) results show that the content of the wool powder has no obvious influence on the soft-segments, but the storage modulus of the polyurethane films will increase with the increase of the wool powder. In addition, during the drying process under a certain temperature, the wool powder destroys the crystallinity of hard segments of the polyurethane resin. This increase the degree freedom of the macromolecule chain segments in polyurethane. At the same time, the glass temperature of the polyurethane is improved on some degree.With the increase of the content of the wool powder, there is an evident decrease in the breaking tension, breaking elongation, fracture toughness of the blended films. This is because after the addition of the wool powder, there is no new chemical bond function between the powder with polyurethane, the cohesion is very low, so there are a great deal of gaps at the place of interface, this can also help the loss of the tension properties. After the addition of the wool powder, there is a significant increase of the water vapor permeability of the blended polyurethane films. Before the content of the wool powder reaches 30%, because of the covering of the polyurethane resin, the wool powder can not be placed continuously. There are no enough water vapor can permeate the films, the increase effect of water vapor permeability is not obvious. But when the content of the wool powder can reach to 30%, there will be a dramatically upgrade in water vapor permeability. The continuously placed powder will increase greatly, there will be a great number of gaps at the place of interface between the wool powder and the polyurethane. Once the gaps can be connected, there will be many tunnels can let water vapor permeate the films. Especially, when the wool powder accounts for a half of the film, even the moisture absorption of the surface of the films increases a lot. There are a lot of tunnels brought from continuous wool powder to permeate the water vapor, therefore, the water vapor permeability increased enormously.We blend the wool powder into the polyurethane to coat on the fabrics. With this method, the water vapor permeability of these coated fabrics can be improved. With the increase of the content of the wool powder, at the same time, the performance such as tensile properties, still water-fast pressure, wear resistance of the coated fabrics will decrease in a definite degree. The experiment...