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Projects on textiles

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Hempsys

The quality of hemp fibre required for the production of high quality textiles produced by the long fibre spinning process can be obtained only through careful control of the supply chain.

The production chain starts at the primary production and the end product performance is relying on the choice for variety of hemp crop and the agronomic regime. The influence of environmental factors (soil, climate) on fibre quality development can be understood from registration of the meteorological data, combined with the recording of the methods of handling along the various steps of fibre preparation for end-product manufacturing.

Design of the fibre production chain has to include the organization and harmonization of the flow of products from one element in the chain to the other. The economic driver for the production should be rather the optimal quality than the optimal quantity of product. Therefore a strict quality control system needs to be designed at all transition points giving value in the chain. Quality however is not the same at the various levels.

Integration of the concept of quality is involving the multidisciplinary skills from farmer to fashion and design. The quality of the consumer product is defined by softness, appearance, luster, strength, which is added for a large part in the finishing process of the fabric.

Flax for textile

It has been recognised that for world wide trade in commodities like cotton, a standardised qualification system is a necessity and therefore normalised instrumental procedures have been developed and introduced in the sector. For the other textile fibres derived from plant bast tissues (flax hemp, ramie, jute, etc.) so far no uniform classification system exists, which is limiting the expansion of the industry and impeding innovation and new product development. The ASTM subcommittee (D13.17) has been established on flax (linen content) products, to address the various quality aspects.

Research has been conducted on the fibre formation and quality development in flax. The effects of processing on the properties of the end product have been monitored from the traditional sequence of retting, breaking and scutching to hackling and yarn production. Objective methods and standard protocols for quality assessment of fibres and fibre products have been addressed in various R&D programmes. Fundamental aspects of flax fibre formation have been studied in close cooperation with the Kazan Institute of Biochemistry and Biophysics.

EU has been market leader in the world production of high quality linen fabrics, but competitiveness with synthetic and natural fibres (cotton) has ousted its position on the textile market. ISO-standards for different agrofibre products then can be introduced in the whole sector, which will have its positive effect on the infrastructure leading to enhanced trade and industrial use of renewable resources and especially fibre crops. Currently increasing volumes of agrofibres are processed especially in automotive industry, which trend is expected to expand in the near future to other industrial branches.

Dyeing and bleaching

A new method for safe and environmentally friendly bleaching and dyeing of coir fibres and yarns has been developed in cooperation with Triade BV, Naaldwijk (NL), and the research institute of the Indian Coir Board (CCRI) in Allepey, Kerala. The bleaching step in de process of dyeing coir fibres and yarns has, apart from whitening of the coir, also positive effects on the susceptibility of the dyes to the yarns, colour brightness and appeal and the yarn softness.

Various types of coir fibres and yarns have been investigated in this research project. The mechanical strength of the fibres was tested before and after bleaching. The results showed no significant strength loss, moreover an improvement in some cases due to the loss of non-strength material during bleaching.

Hydrogen peroxide was found to yield and excellent bleaching effect and to combine an environmental friendly bleaching technology with a considerable increase in whiteness of the fibres. Optimum process conditions have been developed for fibre penetration, bleaching temperature and time, consistency and peroxide concentration.

Effluent analysis showed that no environmentally harmful chemicals were present in the bleaching liquor after bleaching the fibres. Re-use of the bleaching liquor after adjusting the pH and adding new peroxide is possible with a decrease in whiteness of only 4%. The costs of bleaching and quantities of wastewater decrease significantly by re-using the bleaching liquor.

As a result of the pilot-scale experiments, industrial scale trials (180 kg) were carried out in India. Many industrial coir manufacturers were present at the trial and seminar, which were organised by the project team. The trial and seminar were received enthusiastically by the manufacturers, because of the superior results of the bleaching and dyeing compared to the conventional methods. Especially the whiteness and softness after bleaching and the brilliance and colourfastness after dyeing were noted by local experts.

Geotextiles

In a project with producers of geotextile materials in the Netherlands, a project was carried out to enhance the performance of plant fibre based products for the application in civil and hydraulic engineering. Geotextiles produced from plant fibres for soil erosion control and vegetation establishment were treated to enhance their durability. Biodegradable geotextiles based on coir, jute and flax were acetylated to increase their service life. Depending on the degree of modification by changing the processing conditions, the lifetime of the fibre products can be adjusted.

Untreated, treated and commercially available geotextiles have been monitored for several years in a field trial on the slopes of a brook with fluctuating water levels. During this trial service life, soil erosion and vegetation establishment was monitored. The positive effect of acetylation on the functional life-time of vegetable fibre based geotextiles found with the laboratory soil burial tests has also been found in the field trial.