engleski

Flax Cottonisation by Ultrasound

In most instances, flax is processed with the aim to obtain very fine fibres from coarse technical fibres, which are then spun into very fine yarns (1tex). This is economically justified by high price of thus processed flax at the market. All the methods for obtaining fine flax fibres from technical ones are based on the same process: the process of cottonisation, consisting of partial or total removal of pectin binding the elementary flax fibre cells into technical fibres. The goal is thus to obtain finer and shorter bundles of technical fibres, or even loose elementary fibres. Ecological problems connected with the production of coarse and fine flax technical fibres have significantly suppressed flax cultivation during the second half of the 20th century. This is because flax is most commonly processed into fine fibre by retting, i.e. in a biological procedure where large quantities of fresh and decarbonated water are used. After the treatment, the water has low oxygen content and is polluted with microorganisms. In order to eliminate these problems, a number of alternative cottonisation methods have been proposed. This paper presents investigation results of ultrasound application in cottonisation of technical flax. Coarse technical fibres are treated with ultrasound under varying conditions. Cottonisation is performed in various media (water, water solution of sodium carbonate), exposures to ultrasound varied in length and various temperatures were used. The indicator of processing efficiency is defined by the quantity of pectin removed (gravimetrically) and by specifying the separability of technical flax (investigating the morphology) after the ultrasound treatment. Investigation results prove that ultrasound is not only an ecologically favourable cottonisation method (avoiding chemicals and microorganisms), but offers also interesting and positive effects on the material itself.

linen; flax; cottonisation; ultrasound; ecology

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