engleski

Biodegradabilty of Modacryl/Cotton Plied Yarns

Biodegradable fibre blends are composed of biodegradable fibres and fibres that are not. These blends are usually less expensive compared to pure biodegradable fibres. The presence of the biodegradable fibre makes the mixture suitable for partial biodegradation, making it an alternative to the use of fully biodegradable fibres that are more expensive. The concept of introducing materials of a specific degradation time primarily requires defining a period in which the material should perform the intended role (without significantly losing their properties). It should be selected so that the gradual deterioration of their properties is proportionate to the performance of the intended role. The goal of this research is to investigate the influence of plied yarn fineness and thus its structures, on the biodegradability period i.e. deterioration time. The plied yarns are produced by twisting together two single yarns of same fineness. Single yarns are spun in Z direction in following fineness: 20, 16.7, 14.3 and 12.5 tex. During plying, the yarns were twisted in S direction where fineness of plied yarns amount 40, 33.4, 28.6 and 25 tex. Each single yarn were spun with blend of 55% modacryl / 45% cotton fibres. The biodegradability of the plied yarns was investigated using soil burial tests under real conditions for a period of 25, 50 and 100 days. The influence of soil and atmospherics conditions on the plied yarns biodegradability was evaluated by measuring and comparing changes in fineness and tensile properties. By increasing the period of samples buried in the soil, breaking force and tenacity decrease, while fineness and breaking elongation increase. Obtained results are an obvious indicator of sample degradation. The trend of changes in yarn fineness (increase in fineness due to partial decomposition of plied yarns) after the total burying period is not visible. That is, the largest change in yarn fineness is visible for the coarsest and the finest yarn (by an average of 18.5%). This can be explained by the different yarn twist influence where twists provide a certain yarn compactness. For example, the plied yarn fineness of 14.3 tex has more twists (S800 m-1) than yarn of 20.0 tex (S670 m-1) and 12.5 tex (S760 m-1), which organize fibres more compactly, providing greater resistance to the soil and the atmosphere to penetrate within its structure. The smallest decrease in yarn finesses (by an average of 11.8%) is present with the 16.7 tex yarn. Comparing the results of plied yarns breaking force and longation, it is evident that the largest decrease of breaking force (higher decomposition) have coarser yarns. Larger degradation occurred due to less compactness of the yarn structures. Tenacity is continuing the trend of breaking force, i.e. the largest decrease in yarn tenacity is visible for coarser plied yarns. The result of the research clearly demonstrate the importance of yarn structure, as the basic two-dimensional semi- finished product intended for making knits and woven fabrics, when designing biodegradable textile products for different purposes.

Biodegradability, Modacryl/Cotton plied yarn, Soil burial test, Yarn fineness.

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