Airborne Wind Energy is an emerging technology that harnesses the power of the wind by using tethered wings. Among the flying devices are ram-air wings made from coated textiles that utilize dynamic pressure to gain their shape. During flight operation, the textiles are subject to long-term weathering exposure and high aerodynamic loads, leading to degradation processes and the ultimate loss of functional properties. Therefore, a key challenge in the Airborne Wind Energy industry is the improvement of the textile durability of ram-air kites. This thesis contributes to solving this problem by investigating the effects of 200 hours of artificial weathering and 36 weeks of natural weathering on the mechanical properties of selected state-of-the-art kite textiles and the underlying principles of degradation. The tested materials involve two polyamide 6.6 rip-stop weaves coated with polyurethane and silicone, as well as a coated plain weave and a flexible laminate made from high-modulus polyethylene. The results show that all materials are clearly affected by the exposure to weathering, but the implications on the mechanical properties and the rate of degradation vary significantly. The high-modulus polyethylene textiles demonstrate superior tensile properties, but severe coating degradation causes a significant rise in air permeability. Consequently, the high-modulus polyethylene textiles are considered unsuitable for application in ram-air kites, as the high permeability prevents the kite from maintaining sufficiently high pressure. In contrast, the silicone coated polyamide 6.6 textile exhibits superior air permeability after long-term exposure to weathering conditions. FTIR spectroscopy and TGA indicate that the reduced permeability could arise from curing processes in the silicone coating.

Graphene is a two-dimensional carbon based material with unique properties, such as electrical and thermal conductivity. When a textile is coated with graphene, it becomes conductive, while remaining low weight, soft, breathable, flexible, and stretchable. The purpose of this thesis is to investigate what products are suitable to be made with graphene textiles, by using the method Material Driven Design (MDD). Reflections are also made to determine how this method is affected by being applied to a two-dimensional material. To help with this, three kinds of graphene textiles from the company Grafren AB are investigated; conductive textiles, heatable textiles, and textile sensors. The product goal is to develop a portfolio containing 5-8 conceptual products based on these graphene textiles. The process includes conducting an investigation of the technical properties of the material, a user study, and a benchmarking study. This is done to understand the limitations and opportunities of the material, how it is perceived, and what similar materials there are on the market. After that, the material's characteristics are reflected upon to establish a vision for how it should be used in future applications. Then, to follow that vision, a user study is conducted to investigate how people perceive different materials and products, in order to create design guidelines to ensure that the material and product are perceived as intended. Next, concepts are developed according to the previously determined guidelines. To achieve this, idea generating workshops are conducted, where 14 concepts are selected for further development. The portfolio is then created, meant to inspire further usage of the material. It contains the following seven concepts. A heatable textile meant for cooking on camping trips. A fabric containing sensors that can notify when it is damaged. A keyboard made of fabric, for an easy and comfortable use and transportation. A stroller with sensors and heaters, for a more comfortable and safe user experience. A conductive jacket that can electrocute mosquitoes that come in contact with it. Pressure sensors in a carpet that can keep track of the people inside and provide assistance in emergencies. Gloves with sensors in them that can translate sign language live to text or speech. Since MDD heavily focuses on the sensorial qualities and physical characteristics of the material, the method needs to be adapted to become useful when working with such a versatile two-dimensional material. Fortunately, most adaptations can be made fairly easily. The timing of each step should also be considered, to ensure that the vision and guidelines can be made specific enough to be useful.