In China, for thousands of years Bamboo is considered as a rich natural resource which is useful in many different industries. Its greatest advantage is biodegradability, quick and dense growth, the possibility of natural processing and also non-use of pesticides and herbicides. In the last decade, the use of bamboo fibers, both natural and regenerated bamboo fibers, has been steadily increasing. Products made of bamboo have a lot of good properties, such as low price, durability, high absorption, pleasent touch, porosity, air permeability, antibactirial properties and UV protection. They are also environmental friendly and have ability of bleaching and dyeing. Regenerated bamboo fibers are mostly used for underwear, sportswear, t-shirts and socks, but because of UV protection, they are also desirable for towels and summer clothes. Due to its antibacterial properties, bamboo is suitable for hygiene products and medical supplies. The purpose of the diploma work was to determine how the permeability properties of fabrics with a mixture of fibres from lyocell and natural bamboo fibers in weft differ from cotton fabrics. Fabrics were woven in three different densities (basically, the density in all fabrics was 20 threads/cm, the weft density was 15, 20 and 25 threads/cm) and in three different weaves (plain weave, twill 2/2 (K2/2) and twill 1/3 (K1/3)). The results showed that woven fabrics with lyocell/bamboo yarn in weft have biger air permeability by approximately 15 % and about 8 % more water vapor permeability. Fabric woven in the twill 1/3 also have slightly higher air permeability and water vapor permeabilitiy, due to the more porous structure and the distribution of the pores. Cotton fabrics have 5 % better thermal conductivity. Woven fabrics made in plain weave also have better thermal conductivity in comparison with other two weaves. We have determined that the permeability properties in addition to the material used in the weft are influenced by the construction parameters such as the density of fabrics and weave. The air permeability and water vapor permeability is influenced by the open area of fabrics, porosity and hydraulic diameter of pore and the number of pores, while thermal conductivity is inversely proportional to the open area of woven fabrics. The number of pores are smaller, where there are the greater open area of the fabric, the porosity and the hydraulic diameter of the pores, greater air permeability and the water vapor permeability. For thermal conductivity, the opposite is proportional to the open area.
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