3D printing of thermoplastic PI and interlayer bonding evaluation

Thermoplastic polyimide (TPI) has a narrow processing temperature range, high viscosity, and high viscous flow temperature (Tf). These properties lead to difficulties in 3D printing and traditional forming with TPI owing to deformation caused by thermal stress, stratification, and other problems. The thermal stability of TPI raw materials and 3D printing filaments were analyzed in this study. Relationships between the Tf of the 3D printing filament and the starting printing temperature were studied. The influence of the 3D printing temperature on the interlayer bonding force of a 3D printed part was studied. The appropriate printing temperature range of TPI 3D printing was found to be 320-340 °C. When the printing temperature was 335 °C, the interlayer bonding force was 344.5 N. When the printing temperature was 340 °C, the interlayer bonding force decreased to 260.5 N. Within the appropriate 3D printing temperature range, complex TPI components with good interlayer bonding and high temperature resistance could be printed.