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Issue 06/2015

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From Science & Research

From Science & Research From Corn to T-shirt Rapid Textile Prototyping at ITA in Aachen This article presents the Rapid Textile Prototyping method developed at the Institute of Textile Technology (ITA) using the example of the production of a T-shirt made from PLA. One of the core competences of the Aachen, Germany based ITA is the representation of nearly complete textile process chains, beginning with raw materials such as natural fibers or granulates of synthetic material and ending up with read-ymade end products or pre-products. In the field of yarn production, spun yarn, multifilament yarn, monofilament yarn, as well as high modulus filament yarn can be produced at the ITA. The produced yarns can then be processed in all classic methods of surface production like weaving, knitting, warp knitting, braiding, as well as nonwoven surface production in bonded yarn or fiber layers. Finishing processes, like thermosetting and the dyeing of cloth bales, are outsourced to partner companies. After finishing, the cloth can be cut and joined into textile pre-products by sewing or welding. Furthermore, fiber composites can be laminated in moulds, or impregnated with resin through infusion, and hardened in the autoclave. The Rapid Textile Prototyping method, developed at ITA, shows the realization of a fabric with all the needed process steps starting with yarn spinning. All the parameters necessary for the production of a fabric can be identified in a top-down process, whereas the choice of the appropriate polymer, or the appropriate natural fiber, can be made through the “bottom-up” process. Picture 1 illustrates the different steps involved in the production of a T-shirt made of PLA using the Rapid Textile Prototyping process developed by ITA. The steps, which this manufacturing process require, are the following: • Melt spinning • Texturing • Knitting • Finishing • Ready-to-wear manufacturing A multifilament yarn with POY (partially oriented yarn) characteristics is produced from PLA in the melt spinning process. PLA is a material that crystallizes slowly in the spinning process, which means that crystallization continues on the bobbin.The heat produced during this post-crystallization accumulates in the inner yarn layers. This heat accumulation results in a shift of the amorphous phase past the glass transition temperature in parts of the polymer melt, which leads to slipping yarn layers in the lapping process and hence to an instable bobbin formation. Using a FDY (fully drawn yarn) process with heated godets at crystallization temperature leads to a completed PLA crystallization in the winding process. [3] The process speed is reduced from 3,500 m/min to 2,500 m/min. Two spinning days are needed to realize the needed yarn quantity of 20 kg (in 1 kg bobbins) Melt spinning [2,500 m/min] Texturizing [600 m/min] Weft knitting [0.5 m 2 /min] Heat setting & deyeing [0.5 m/min] (external) Cutting & sewing Raw material Rapid textile prototyping Product PLA pellets PLA T-Shirt Picture1: Rapid Textile Prototyping at the ITA, exemplary for PLA 40 bioplastics MAGAZINE [06/15] Vol. 10

From Science & Research The yarn is crimped with a false twist in the following texturing process in order to improve feel and heatinsulating capacity. An adjustment of the spin finish has an intense influence on yarn damage and may help a better manufacturing of the PLA yarn. The process speed is 600m/min and after adjusting the parameters, 20 kg material can be textured with several parallel positions within one day. By: Nicole Mevissen, Mathias Beer, Yves-Simon Gloy, Thomas Gries Institut für Textiltechnik (ITA) der RWTH Aachen University Aachen, Germany The next step of the process chain is manufacturing a textile surface. The textured multifilament yarn is delivered with a speed of 140 m/min at 20 knitting positions in the circular knitting machine, resulting in a single jersey. Roughly 0,5 m 2 of knitted cloth are produced per minute. In the knitting process, an elastane filament yarn is plated to the PLA yarn in order to adjust the elongation properties to a reference product made from polyester yarn. After the knitting process, thermosetting and dyeing are processed with about 0,5 m/min. The last step includes cutting the apparel pattern and manufacturing the ready-to-wear T-shirt. Finally, the organic T-shirt is compared to the reference model, made from polyester, in standardized textile testing methods (weight per unit, strength/elongation, air permeability, stitch density, thickness). As the textile process chain can be examined completely at the ITA, new products can either be developed from existing material, or already existing products can be modified by using new material. One of the core challenges is usually finding and setting the appropriate process parameters for the new product or material. For this purpose, existing processes are adjusted according to the requirements, or, if necessary, completely new processes or process steps and the needed machine technology are developed. The ITA can support the establishment of new manufacturing processes and their preparation for industrial production. Acknowledgment: Special thanks are due to Dr. Roy Dolmans for supervising a master’s thesis on the procedural dimensioning and manufacturing of the PLA T-shirt. Further thanks go to the company Dolinschek GmbH, Burladingen, who supported the manufacturing process with their help in thermosetting and dyeing. References: [1] B. Linnemann, M. Sri Harwoko, T. Gries, Faserstoff-Tabellen; Polylactidfasern (PLA), 1. Ausgabe, Institut für Textiltechnik (ITA) der RWTH Aachen, Aachen, 2004 [2] Endres, H.-J.; Siebert-Raths, A.: Technische Biopolymere - Rahmenbedingungen, Marktsituation, Herstellung, Aufbau und Eigenschaften; München, Hanser Verlag, 2009 [3] Dolmans, R.: Bewertung kommerziell erhältlicher, biobasierter Polymere in der textilen Filamentextrusion, Dissertation, Shaker Verlag, Aachen, 2014 Institut of Textile Technology (ITA) der RWTH Aachen University ITA belongs to the top three institutes of RWTH Aachen University. Its core competences are in the development of textile machinery and textile machine components, in high-performance fiber materials, in manufacturing processes, in spinning supply chains, and in the development of innovative textile-based products in the fields of mobility, construction and living, and energy and health. The central fields of technologies are efficiency of material and energy, integration of functions, and integrative manufacturing technology. The institute employs about 110 scientific researchers including mechanical engineers, chemists, physicians and economists. bioplastics MAGAZINE [06/15] Vol. 10 41

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