Abstract Additive manufacturing (3D-printing) is a rapidly emerging technology grouped under the heading of Industry 4.0 and revolutionises the way products are created. One emerging area is textiles (apparel) where additive manufacturing allows the rapid fabrication of products that are not easily produced using traditional manufacturing approaches. In this review, we provide an overview of recent developments in textile additive manufacturing highlighting this exciting and rapidly growing research area and offer insights into the future perspectives of this promising and innovative technology.

https://www.tandfonline.com/doi/pdf/10.1080/23311916.2022.2048439?needAccess=true

Textile additive manufacturing: An overview

3D printing on textile fabrics can be used to create composites with position-dependent mechanical, water-resistant, magnetic or other properties. An important prerequisite to use such composites technologically or for design purposes is a sufficient adhesion between both materials. While previous studies revealed that soft, elastic printing polymers were advantageous to prepare connections with a high adhesion, not much research has been performed yet on the dependence of the adhesion on textile fabric structure, heat post-treatment, and the influence of washing, which is necessary for most applications of such composites. Here we investigate composites from thermoplastic polyurethane (TPU) 3D-printed on two different woven cotton fabrics. Besides the expected strong correlation of the adhesion with the distance between nozzle and printing bed, we find a higher adhesion on the thinner fabric and an increase in the adhesion after one washing cycle.

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Influence of washing on the adhesion between 3D-printed TPU and woven fabrics

The microstrip patch antenna (MPA) with a thermoplastic substrate has been widely used in wearable sensors primarily due to its lightweight, flexibility, strength, and compactness. But up till now, little has been conveyed on the use of three-dimensional (3D) printed thermoplastic polyurethane (TPU) on cotton-lycra woven (CLW) fabric-based substrate as a wearable sensor. This study presents a novel and scalable approach for characterizing, simulating, and fabricating the substrate for wearable sensor applications. In this study 3D printing of TPU on CLW fabric (70% cotton (on the warp side)-30% lycra (on the weft side) using fused filament fabrication (FFF) process) has been reported with a tradeoff between flexibility and strength (of a substrate for wearable sensor applications). The rheological, mechanical, morphological, four-dimensional (4D), and resonance frequency (RF) characterization of the substrate has been established. As regards rheological properties, the melt flow index (MFI) of primary (1°) recycled TPU was observed as 29.758 g/(10min). Further, the optimized 3D printing settings of TPU were obtained based on the mechanical testing (minimum stiffness, maximum peak strength (PS), maximum Young's modulus (E), and maximum strain energy (SE)) which comes out to be 225°C nozzle temperature, 18 mm/s printing speed and 60% infill density with a stiffness of 3.311 N/mm and PS of 9.628 MPa. The mechanical properties of TPU printed on stretched and unstretched CLW fabric were tested for lower stiffness (more flexibility). To ascertain the mechanical properties, porosity analyses of samples printed on CLW fabric have been performed based on scanning electron microscopy (SEM). For dielectric properties, and RF characterization, the ring resonator (RR) test was performed based on a Vector network analyzer (VNA). Finally, 4D characterization of the substrate was performed by applying a load from 0 to 25 N, resulting in programable RF output (in the industry scientific and medicine (ISM) band).

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Three-dimensional printed thermoplastic polyurethane on fabric as wearable smart sensors

The article reviews the literature focused on investigating the adhesion strength between the 3D-printed polymers and the textile substrates, and its dependence on different factors related to materials, printing parameters, and fabrics type and structure. 3D printing (3DP) onto textiles is a domain in expansion as it allows developing products with new functionalities by gathering the advantages of design freedom, tailor-fit, comfort, variety, and mass customization provided by both the textiles and the additive manufacturing technology. In this context, it becomes important to document and understand how the adherence of different 3D-printed molten polymer to diverse textiles substrates can be improved for obtaining products more resistant to specific conditions, such as washing, wear, or ironing. Following a systematic search of electronic databases, 28 articles were selected for the full-text read and data extraction. The summarized information was grouped per 3DP material and analyzed factors, and then discussed in terms of variables influencing the adherence, including pretreatments and post-treatments applied to fabrics or 3D-printed onto fabrics specimens and objects. A case study of a customized polylactic acid–cotton-elastane wrist–hand orthosis is also presented to exemplify the modality in which the information synthetized in this review can be used in the development process of a new product. 

3D Printing onto Textiles: A Systematic Analysis of the Adhesion Studies

The double-weave structure of a fabric allows for the use of different materials and weave structures for the upper and lower layer, which can be advantageous in the functionalization of 3D printed textiles. Therefore, the aim of this research was to investigate the influence of simple and double-weave structures on the adhesion of 3D printed fabrics. From this perspective, we investigated the influence of different twill derivates and weft densities on the adhesion force. We produced fabrics specifically for this study and printed them with a polylactic acid filament using Fused Deposition Modeling technology. The T-peel test was performed to measure the adhesion, and the results were statistically analyzed. A morphological study of the surfaces and cross-sections of the 3D printed fabrics helped us interpret the results. We found that adhesion was higher for double fabrics when printed with a smaller z-distance, where the molten polymer reached the lower layer of the fabric and adhered to it. The opposite was confirmed when printing with a larger z-distance, where adhesion was higher for simple fabrics. Both weave and density had a significant effect on adhesion in all cases. Surprisingly, different twill derivatives generally had a greater influence on adhesion than density.

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Influence of Simple and Double-Weave Structures on the Adhesive Properties of 3D Printed Fabrics

3D printing belongs to the emerging technologies of our time. While it enables producing new structures and makes individualized products affordable, 3D printed objects still suffer from low production speed and often insufficient mechanical properties. Both these problems can be tackled by combining 3D printing with substrates prepared by conventional technologies, e.g. textile fabrics. In this case, the adhesion between both partners is most challenging and defines for which possible applications such composites are suitable. Here, we report on a new approach to increase the adhesion between 3D printed materials and warp knitted fabrics, showing that in some cases a thermal after-treatment, in the simplest case performed by ironing, is able to significantly increase the adhesion between both materials.

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Daniel Görmer

Papers

The influence of thermal after-treatment on the adhesion of 3D prints on textile fabrics

Influence of washing on the adhesion between 3D-printed TPU and woven fabrics