简 介：In 2004, the European Commission received a petition, presented by Dow Chemicals, for the establishment of a new generic name, in accordance with Directive 96/74/EC. The proposed name was lastol and the suggested definition is reported in the following: fibre composed of at least 95 % by mass of crosslinked macromolecules, with between 5 to 25 % crystallinity, made up of ethylene and at least one other olefin and which, if stretched to 1.5 times its unstretched length, rapidly reverts substantially to the unstretched length when the tension is removed, and maintains its elastomeric property after exposure to temperature of 170 C and beyond . The Commission therefore convened a meeting of the technical working group for Directive 96/74/EC on textile names, comprising governmental experts representing each Member State. The meeting was held in Brussels on 20th September 2004. The application was considered justified by the group of experts, who recommended an amendment to the list of fibre names in Annex I of Directive 96/74/EC. As a result of several discussions with technical experts, the name proposed by the Commission for the new fibre is elastolefin and it will be thus indicated for the purpose of this report. In December 2004, the Directorate General Joint Research Centre (JRC) was asked to conduct experimental work to check the validity and suitability of the testing methods proposed by the applicant for the identification, quantification and characterisation of elastolefin, such as elongation at break, elastic properties and crystallinity degree. The results of this investigation were presented during the fifth technical meeting of the network of national experts on textile labelling, held in Ispra on 21st October 2005. Based on these data, experts judged that the identification methods, based on FT-IR and DSC analysis, were suitable for the purpose and that there was no need to organise a ring trial. FT-IR spectroscopy can identify the olefin nature of the new fibre and DSC can discriminate among elastolefin, polyethylene and polypropylene based on the different melting points. Experiments showed that the normal pre-treatment based on a Soxhlet extraction with petroleum ether is not applicable to elastolefin, due to high mass loss. Alternative methods were tested and experts agreed on the applicability of a pre-treatment similar to the one described in Directive 96/73/EC, substituting petroleum ether with acetone, in the case of binary mixtures of elastolefin with other fibres (wool, animal hair, silk, cotton, flax, true hemp, jute, abaca, alfa, coir, broom, ramie, sisal, cupro, modal, protein, viscose, acrylic, polyamide, polyester or elastomultiester). Moreover, in the case of binary mixtures elastolefin-acetate, a pre-treatment that foresees to immerse for 10 minutes samples in an aqueous solution maintained at 80 C, containing 25 g/l of 50 m/m ortophosphoric acid and 50 g/l urea, is recommended. A series of fabric samples, containing elastolefin in mixture with wool, cotton, polyester, polyamide, aramid and polyester/cotton in various percentages, were quantified both using the manual method and the chemical ones described in Directive 96/73/EC. The chemical methods 1-8, 10-11 and 14 were tested and considered suitable for the quantification of elastolefin in mixtures with other fibres. Methods repeatability was good, as demonstrated by the low values of the relative standard deviation (RSD), used to measure the dispersion of the distribution of test results in one laboratory. The same considerations are true for the manual separation method described in Directive 96/73/EC, which was applied to binary mixtures of elastolefin with cotton, wool and aramid and to ternary mixtures with polyester/cotton. As all the above-mentioned methods have already been validated at European level, experts considered a ring trial unnecessary and these methods may become the official ones to quantify elastomultiester in mixtures with other fibres. The correction factors d for chemical methods 1-8, 10-11 and 14, that take into account the mass loss of the insoluble component, were calculated based on the analyses of samples of pure elastolefin. In particular, the correction factors d for chemical methods 4, 6 and 7 were evaluated through a ring trial. The established values for d were 1.00 for all methods, except method 6 for which the d value was 1.01. The JRC, based on the proposal of the applicant and on the chemical composition of the new fibre, that is ethylene based, proposed an agreed allowance value of 1.50, equal to the one for polyethylene, and experts from Member States accepted this proposal. As characterisation of the new fibre, elongation at break and elastic properties both without and with heat treatment (2 minutes at 220 C) were evaluated for samples of pure elastolefin from bobbins and extracted from fabrics. Moreover also the crystallinity degree of samples was measured. The BISFA method for bare elastane yarns was used to measure elongation at break. Results confirmed that yarns from bobbins can be extended up to 500 % and more without breaking, whereas yarns extracted from fabrics showed elongation at break of around 100 % both without and with heat treatment. Elastic properties were measured using a BISFA method and a method developed at the JRC. The two elongation-based methods were applied both using a tensile testing machine and manually. Results demonstrated that the fibre can be considered elastic when stretched at 50 % elongation. In fact with both methods recoveries after three or five cycles are usually higher than 85 % and permanent deformations lower than 10 %, as it is the case for elastane when stretched at 200 %, that means in the same conditions described in its definition. Moreover experiments confirmed that heat treatment at 220 C for 2 minutes did not influence the elastic properties of elastolefin yarns. Comparison among results obtained with methods applied manually or with a Textechno instrument showed a very good agreement. A method based on DSC was successfully applied to evaluate the crystallinity degree of elastolefin fibre, which nowadays is about 17 %. On the basis of the experimental results and of discussions with representative experts from Member States (meetings on 1st October 2004, 4th March 2005, 21st October 2005 and 28th June 2006), the definition agreed and proposed for elastolefin is: fibre composed of at least 95% (by mass) of macromolecules, partially cross-linked, made up of ethylene and at least one other olefin and which, when stretched to one and a half times its original length and released, recovers rapidly and substantially to its initial length . The name elastolefin was chosen, in agreement with experts from Member States, as it fulfils the criteria set up in 2002 by the Commission and the technical experts working group on textile labelling. In fact, according to these criteria, a generic name should not link the fibre to a specific manufacturer, it should be free of rights and it should inform consumers about characteristics of the fibre. The name elastolefin points out that the fibre is elastic and polyolefin based.