Three-dimensional printing has already been shown to be beneficial to the fabrication of custom-fit and functional products in different industry sectors such as orthopaedics, implantology and dental technology. Especially in personal protective equipment and sportswear, three-dimensional printing offers opportunities to produce functional garments fitted to body contours by directly printing protective and (posture) supporting elements on textiles. In this article, different flexible thermoplastic elastomers, namely, thermoplastic polyurethanes and thermoplastic styrene block copolymers with a Shore hardness range of 67A–86A are tested as suitable printing materials by means of extrusion-based fused deposition modelling. For this, adhesion force, abrasion and wash resistance tests are conducted using various knitted and woven workwear and sportswear fabrics primarily made of cotton, polyester or aramid as textile substrates. Due to polar interactions between thermoplastic polyurethane and textile substrates, excellent adhesion and high fastness to washing is observed. While fused-deposition-modelling-printed polyether-based thermoplastic polyurethane polymers keep their abrasion–resistant properties, polyester-based thermoplastic polyurethanes are more prone to hydrolysis and can be partially degraded if presence of moisture cannot be excluded during polymer processing and printing. Thermoplastic styrene compounds generally exhibit lower adhesion and abrasion resistance, but these properties can be sufficient depending on the requirements of a particular application. Soft thermoplastic styrene filaments can be processed down to a Shore hardness of 70A resulting in three-dimensional printed parts with good quality and comfortable soft-touch surface. Finally, three demonstrator case studies are presented covering the entire process to realize the customized and three-dimensional printed textile. This encompasses product development and fabrication of a textile integrated custom-fit back protector and knee protector as well as customized functionalization of a technical interior textile for improved acoustic comfort. In the future, printing material modifications by compounding processes have to be taken into account for optimized functional performance.
The production of plastic has grown exponentially over the past few decades and with it the amount of plastic waste leaking in the environment, where it fragments into micro-and nanoplastics. This problematic situation stresses the need for increased plastic collection, recycling and reuse rates. Extrusion-based additive manufacturing (AM) and especially fused filament fabrication (FFF) offer an efficient and effective method to reuse and upcycle recycled plastic. This study focuses on poly(ethylene terephthalate) (PET), which has a broad application window and its recycling is therefore environmentally and economically favorable and sustainable. Therefore, this study involves the thermal and mechanical behavior of recycled PET after extrusion and 3D printing. The extrusion parameters are optimized by performing a complete physico-chemical and thermal analysis of the obtained filaments and they were compared with commercial virgin and recycled PET. Moreover, the influence of the applied processing conditions on the degree of crystallinity and mechanical properties is investigated. The filaments are then used for FFF, where various printing parameters are altered to obtain the optimum printing conditions (i.e. printing temperature, the build plate temperature, fan cooling and printing directions). The effect of the degree of crystallinity of semi-crystalline PET is investigated via altered printing parameters, showing superior mechanical properties for an increasing degree of crystallinity. To verify the portability of the obtained optimized print parameters, two different FFF printers are used. The use of recycled PET as feedstock for FFF supports the efforts for improving the sustainability of plastics by valorizing PET waste, and prolonging the lifecycle of PET.
Fibre-matrix adhesion affects fibre-reinforced composites' mechanical properties, a process which can be improved by applying appropriate sizing on the fibre. Transverse bending tests and Scanning Electron Microscopy (SEM) can help quantify this effect This paper investigates if modal damping measurements are a reliable alternative for quantifying fibre-matrix adhesion. When a composite sample is vibrating, part of the dissipated energy is due to the internal friction. More internal friction and slipping at the fibre-matrix interface is expected with a weaker fibre-matrix bond, hence increasing the amount of dissipated energy, which in turn is proportional to the modal damping value. This paper researches two different cases to validate this hypothesis. In the first case, we will use two composite samples of flax fibre, one with and one without sizing. In the second case, we will compare flax and carbon fibre laminates. If the only variable is fibre sizing, better adhesion is related to significantly lower damping and higher resonance frequencies. If composite laminates with different fibre and matrix type are compared, lower adhesion is not necessarily related to increased damping and lower resonance frequencies. However, when combining the damping result with SEM microscopy, it is possible to assess the relative contribution to the internal energy dissipation of the fibre, the matrix and the fibre-matrix interface individually. (C) 2016 Elsevier Ltd. All rights reserved
Although natural resources form the basis of our economy, they are not always used in a sustainable way. To achieve a more sustainable economic growth, resource consumption needs to be measured. Therefore, resource footprint frameworks (RFF) are being developed. To easily provide results, these RFF integrate inventory methodologies, at macrolevel mostly input-output (IO) models, with resource accounting methodologies, of which the Ecological Footprint is probably the best known one. The objective of this work is the development of a new RFF, in which a world IO-model (Exiobase), providing a global perspective, is integrated with the CEENE methodology (Cumulative Exergy Extraction from the Natural Environment), offering a more complete resource range: fossil fuels, metals, minerals, nuclear resources, water resources, land resources, abiotic renewable resources, and atmospheric resources. This RFF, called IO-CEENE, allows one to calculate resource footprints for products or services consumed in different countries as the exergy extracted from nature. The way the framework is constructed makes it possible to show which resources and countries contribute to the total footprint. This was illustrated by a case study, presenting the benefits of the framework's worldwide perspective. Additionally, a software file is provided to easily calculate results.
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