# Additive Manufacturing and Textiles--State-of-the-Art
## 5 Printing on Textiles
### Adhesion between Textile and the Deposited Polymer  
Few methods have been investigated by researchers to improve the adhesion between the textile and the deposited polymer. For example, coating fabrics with different polymers before 3D printing with ABS or PLA on them, resulted in a significant increase of adhesion between the polymer and textile fabric [76]. The distance between the nozzle and the printing bed is a crucial factor for the adhesion on textile substrates. With decreasing distance, the adhesion force increases until the minimum distance is reached in which the filament does not clog the nozzle so that the nozzle presses the 3D printing polymer with higher forces into the open pores of the fabric [67]. As shown in Figure 4, the temperatures of the printing bed and the nozzle affects the adhesion, i.e., temperatures of the bed and nozzle increased, the adhesion between the two materials increased [73; 77; 77]. These results, and those of Figure 5 are obtained according [77] at the following parameters: FDM printer Ocabot XXL, producer Prodim, nozzle  
Figure 3: The 3D printing steps of textiles [67; 68; 35; 69]. diameter 0.4 mm, filament: polylactic acid; textile: polyester woven fabric with thickness 0.55 mm and areal density 114 g/m\({}^{2}\); dimensions of the printed rectangles 250 mm \(\times\) 25 mm. The thickness of the printed layer of 0.4 mm was reached by printing two layers. Nozzle temperature 200 \({}^{\circ}\)C, bed temperature 60 \({}^{\circ}\)C, printing velocity 30 mm/2, polymer flow 100%, and extrusion width--0.4 mm. The adhesion tests depicted there were carried out according to DIN 53,530 and evaluated with respect to DIN ISO 6133. Generally, the dependencies found can be attributed to physical, that is, form-locking, connections, while no indications for chemical bonding were found [78]. The influences of textile physical and chemical surface properties such as weaves, surface roughness and plasma treatment or washing were investigated and it is found that the adhesion strength is mostly influenced by both the form locking connections of the thermoplastic and the textile material (textile surface energy) [75]. Textile properties such as the weave pattern or the weft density will have an influence on the overall adhesion properties [65]. The washing process significantly decreased the initial adhesion strength of 3D printed material and therefore, a pretreatment such as plasma, corona or chemical finishing are advised to be applied to guarantee better washing resistance and adhesion properties [79] by enhancing intermolecular interactions like hydrogen bonding or dipole-dipole interaction between the molecules of the polymer and the textile surface before the print [75,80]. In addition, 3D printing speed and the polymer flow were investigated and it was found that there is no significant influence (see Figure 5) [77]. Thermal conductivity, roughness and porosity of the textile materials are other main factors which influence the maximum adhesion strength. Because of stronger mechanical interlocking and higher Van der Waals forces created on a warmer and larger surface area, lower thermal conductivity, higher roughness and mean flow pore size of the textile material could significantly enhance the adhesion strength [79]. Figure 4: Example of the dependence of the adhesion force on the temperature of nozzle (**left**) and bed (**right**) [77] at the specific conditions and materials reported in [77], tested according DIN 53,530 and evaluated according DIN ISO 6133. Figure 5: Example of the dependence of the adhesion force on the printing speed (**left**) and polymer flow (**right**) [77], at the specific conditions and materials reported in [77], tested according DIN 53,530 and evaluated according DIN ISO 6133. In summary, the factors affecting the adhesion of 3D printing of textiles are presented well in the source [81] and can be summarized in to three groups:  
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2. Filament material and its composition;
3. Printing settings with subgroups of;
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5.