Roll-to-roll printed carbon nanotubes on textile substrates as a heating layer in fiber-reinforced epoxy composites Thomas Fischer , 1 Julia R€ uhling, 2 Nora Wetzold, 3 Tino Zillger, 2 Thomas Weissbach, 2 Thomas G € oschel, 4 Matthias W€ urfel, 4 Arved H€ ubler, 2 Lothar Kroll 1 1 Institute of Lightweight Structures, Technische Universit€ at Chemnitz, Chemnitz 09126, Germany 2 Institute for Print and Media Technology, Technische Universit€ at Chemnitz, Chemnitz 09126, Germany 3 Zschimmer & Schwarz Mohsdorf GmbH & Co KG, Burgst€ adt 09217, Germany 4 Department of Electrical Engineering, Wests€ achsische Hochschule Zwickau, Zwickau 08056, Germany Correspondence to: T. Fischer (E - mail: thomas.fischer@mb.tu-chemnitz.de) ABSTRACT: The performance of wind turbines suffers from icing in regions with extreme climate. One approach is to incorporate heating elements into the most susceptible areas of the wind turbine blade as protection against icing and for de-icing. Cost-efficient and reproducible fabrication, as well as easy integration is important due to the large area of wind turbine blades. In this work, multi-walled carbon nanotubes are applied on a 50% poly(ethylene terephthalate) and 50% polyamide non-woven textile substrate by rotary-screen printing. The printed layers function as resistive heating elements in a fiber-reinforced composite. The heating areas are provided with flexographic or screen inline-printed silver-electrodes and can be integrated by means of vacuum infusion into a glass fiber-reinforced epoxy composite laminate. These laminates, which are connected to an intelligent electrical control system, are suit- able for melting ice on the surface of components or for preventing the formation of ice. The first promising experiments on heating structures in a rotor blade of a wind turbine at laboratory scale (2 m length) are the basis of studies on intelligent electrical control of heating structures and their behavior at different temperatures. The heating elements were able to melt a 3–4 mm thick ice layer within 25 min in a climate chamber at 25 8C. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 45950. KEYWORDS: applications; graphene and fullerenes; nanotubes; textiles; thermal properties; thermosets Received 14 July 2017; accepted 19 October 2017 DOI: 10.1002/app.45950 INTRODUCTION The use of carbon nanotubes (CNTs) has established itself in many fields due to their particular intrinsic properties, good processability, and commercial availability. In particular, multi- walled CNTs play a role in optimizing the properties of composite materials. Applications range from structural health monitoring 1–6 and electromagnetic shielding 7–9 to heating sys- tems. 10–12 One of the technologies for the production of carbon-functional surfaces on various substrates such as textiles and plastic films is printing. Technologies that are frequently mentioned in the literature are screen printing, 13–17 ink jet printing, 18–22 and gravure printing. 23–25 Many positive proper- ties of CNTs are associated to many different applications, even in the field of wind turbines, whose blades are largely made of fiber reinforced, in particular glass fiber-reinforced, epoxy com- posite. A specific problem that operators and thus manufac- turers of wind turbines have to deal with is the protection against icing and de-icing of the rotor blades. The reason for this is the increasing opening-up of regions in extreme climatic locations in northern Europe, North America, and European low mountain ranges. The probability of downtime and mainte- nance due to icing increases and thus the energy yield decreases. Manufacturers are looking for systems for de-icing and protect- ing against icing and have derived different approaches. Ener- con, for example, uses hot air that is blown into channels through the rotor blades, while Kemijoki Arctic Technology Oy uses an electrical heated foil developed by the Technical Re- search Centre of Finland (VTT). The literature mentions more companies that are working on solutions. Precise information is often hard to come by, and much is the subject of research activities and extensive series of tests. 26–28 The concept pre- sented here focuses on a comprehensive solution, comprising carrier materials and functional materials, electrical contact, and control of their interactions and specific requirements, and con- siders the entire value chain. For the first time, a layer of CNTs is printed on a nonwoven substrate by rotary screen printing. To ensure good wetting and adhesion, the homogeneous layer forming the substrate has been pretreated mechanically and V C 2017 Wiley Periodicals, Inc. J. APPL. POLYM. SCI. 2017, DOI: 10.1002/APP.45950 45950 (1 of 6)