Fibres textiles
Fibres textiles False-Twist texturing of bio-dyed PLA yarns The fibre production has more than doubled in the last two decades and manmade fibres contributed to 67.5 % of the total fibre market production in 2014 [1]. Among the manmade fibres, polyester, mainly polyethylene terephthalate (PET), is one of the most commonly used fibre materials and is expected to reach a market share of EUR 185.4 billion by 2026. PET is a petroleum-based polymer and with depleting oil resources and growing concern for global warming through carbon dioxide emission, the focus is shifting towards more sustainable and biobased polyesters such as polylactic acid (PLA) [2]. It is an eco-friendly biopolymer synthesised from renewable resources such as corn, sugar beets, and wheat. The production of PLA uses less than 0.03 % of world corn production, making it noncompetitive with the food market [3]. PLA is the first meltprocessable synthetic fibre produced 100 % from renewable resources. In 2000, it was not even close to replacing petroleum-based polymers in commodity applications [4]. Much has changed over the last two decades, demand for PLA rose leading to increased production capacities and thus lower production costs. In addition to being biobased and compostable, PLA fibres have inherently better moisture management, higher limiting oxygen index and wicking properties than PET fibres, which make them suitable for sustainable apparel applications [3]. Despite several advantages offered by PLA in comparison to PET, the worldwide consumption of PLA fibres for textile applications is still only around 54,000 tonnes per year and it has not been used fully to its potential in textiles yet. One of the major drawbacks of PLA is its hydrolytic degradation [5]. This limits the dyeing of PLA fibres using conventional bath dyeing. Dope dyeing, a process where the polymer and the colourant are mixed in the melt phase prior to melt spinning, is an interesting alternative for dyeing PLA. In addition to preventing hydrolytic degradation, this process also uses lower amounts of water and chemicals, making it more sustainable than the conventional bath dyeing [6]. In addition to the dyeing process, the colourants can also affect the environment negatively. The colourants used currently are fossil-based and hazardous to human health. So, there is a dire need to shift to more sustainable biobased colourants [7]. With this goal in mind, the Aachen-Maastricht Institute for Biobased Materials (AMIBM), Maastricht, NL, and the Institut für Textiltechnik (ITA) of RWTH Aachen University, Aachen, DE, combined their expert knowledge in the field of biobased materials and multifilament texturing in order to further advance the use of biobased filaments in textile applications like clothing, home textiles, and medical 24 bioplastics MAGAZINE [05/21] Vol. 16
By: Naveen Balakrishnan, Aachen-Maastricht Institute for Biobased Materials Stefan Hermanns, Maastricht University Fibres textiles Mathias Schmitz, Institute of Textile, RWTH Aachen applications for a more sustainable textile production chain. The polymer used was PLA grade L130 (PLA bv Total Corbion, Gorinchem, NL), combined with a biobased colourant (Curcuma from Sancolor, S.A., Barcelona, Spain). The melt spinning was carried out at AMIBM using a pilot scale melt spinning machine (Fibre Extrusion Technology Ltd., Leeds, UK). It is equipped with a single screw extruder and 4 pairs of heatable godets to perform drawing and a winder that can clock 4200 m/min. A spinning temperature of 200 °C and a winding speed of 2500 m/min was used for the melt spinning trials. Pure PLA as well as dope-dyed PLA multifilament yarns were produced. Fig. 1: Photograph and schematic of the modular false-twist texturing bench at ITA 1m Photo: ITA False twist texturing in a laboratory scale was performed at ITA. The modular false-twist texturing bench at ITA consists of a high-temperature heater, a passive cooling pipe and a twist unit equipped with friction discs which are mounted on three axes. Smooth, partially-oriented yarn (POY) is fed into the machine. Through drawing, twisting and thermosetting, a draw-textured yarn (DTY) is produced. This process is shown in Fig. 1. Both the pure PLA and the dope-dyed PLA fibres were textured. The heater was set to 145 °C and a slow production speed of 200 m/min with a D/Y ratio of 2.07 was used to produce biobased DTY. References: [1] Hussain, T.; Tausif, M.; Ashraf, M.: A review of progress in the dyeing of eco-friendly aliphatic polyesterbased polylactic acid fabrics. Journal of Cleaner Production 108 (2015), 476-483 [2] Polyester Fiber Market: acumenresearchandconsulting.com/polyesterfiber-market, accessed on 03.08.2021. [3] Maqsood, M.; Seide, G.: Development of biobased socks from sustainable polymer and statistical modeling of their thermophysiological properties. Journal of Cleaner Production 197 (2018), 170-177 [4] Drumright, R.E.; Gruber, P.R.; Henton, D.E.: Polylactic Acid Technology. Advanced Materials 12 (2000), Issue 23, 1841-1846 [5] Xu, S.; Chen, J.; Wang, B.; Yang, Y.: Sustainable and Hydrolysis-Free Dyeing Process for Polylactic Acid Using Nonaqueous Medium. ACS Sustainable Chem. Eng. 3 (2015), Issue 6, 1039-1046 [6] Clark, M.; Handbook of textile and industrial dyeing. Volume 2: Application of dyes. Woodhead Publishing Limited; Cambridge; 2011 [7] Alves de Lima, R. O.; Bazo, A. P.; Salvadori, D.M.; Rech, C. M.; de Palma Oliveira, D.; de Aragão Umbuzeiro, G.: Mutagenic andcarcinogenic potential of a textile azo dye processing plant effluent that impacts a drinking water source. Mutat. Res. (2007) 626, Issue 2, 53-60 https://www.maastrichtuniversity.nl/ | https://www.ita.rwth-aachen.de/ POY feed Feeding godet 1 Heater Cooler Production direction Twist unit Feeding godet 2 Fig. 2: Multifilament and textured yarn from PLA and PLA dope dyed with curcuma PLA Multifilament Yarn (POY) PLA Textured Yarn (DTY) Photo: AMIBM 10 cm Winder (DTY) The resulting textured PLA yarns, both pure and dyed, are presented below in Fig. 2. The textured yarn was then knitted into a fabric using a small round knitting machine at the Hochschule Niederrhein, Mönchengladbach, DE. The conducted trials show that there is a great opportunity for biobased materials in applications like clothing, home textiles or medical textiles. They offer the chance to shift the textile value chain from petroleum-based to biobased for a sustainable future. bioplastics MAGAZINE [05/21] Vol. 16 25
