Direct 3D Printing of Thermoplastic Polyurethane Lattices onto Textiles for Cycling Padding: Mechanical Response and Adhesion

The direct additive manufacturing of thermoplastic polyurethane (TPU) onto textiles enables cushioning structures to be integrated into sportswear without the need for adhesive bonding. This study investigates the use of TPU lattices integrated into textiles for cycling padding, as an alternative to conventional polyurethane foams (PUFs). Two lattice structures, combining rotated linear and honeycomb layers, were produced using fused deposition modelling with TPU materials having Shore A hardness values of 60 and 70. The materials were characterised using Fourier-transform infrared spectroscopy and differential scanning calorimetry, while the performance of the padding was evaluated using compression testing at 37 °C, and the adhesion of the textiles was evaluated using 180° peel tests before and after laundering. Compared with PUFs, the TPU lattices exhibited progressive compression without a distinct collapse plateau, as well as repeatable hysteresis loops during 50 loading–unloading cycles. Measured peel-test forces ranged from 15 to 25 N, with limited change after laundering. In most specimens, failure occurred within the textile substrate rather than at the printed interface. The open lattice geometry provides interconnected voids that could improve ventilation, although this was not quantified. These findings suggest that direct TPU printing could be used to create mechanically tunable, adhesive-free textile padding, which would offer potential sustainability benefits due to thermoplastic processing and reduced assembly requirements.