Investigating the tensile properties and crystallinity of 3D-printed poly (ether ether ketone)/poly (ether imide) [PEEK/PEI] blend in the Z-direction by fused filament fabrication

The present study focuses on the evaluation of the effect of nozzle temperature, print speed and layer thickness printing parameters of additively manufactured poly (ether ether ketone)/poly (ether imide) [PEEK/PEI] blend using the fused filament fabrication (FFF) process. Various characterization techniques were employed to investigate printed samples' crystallinity and morphological and mechanical characteristics. These methods included scanning electron microscopy (SEM) and mechanical tests. Additionally, the thermal characteristics of the specimens were evaluated through the use of dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Optimum printing settings were attained at 400 °C nozzle temperature, 40 mm·s⁻¹ print speed, and a 0.10 mm layer height. The PEEK/PEI samples underwent annealing at 200 °C for a duration of 2 h to eliminate any residual thermal stress that may have arisen during the printing process. The annealing treatment resulted in enhanced elastic modulus and tensile strength of the samples. Moreover, the degree of crystallinity ( \({X}_{c})\) $X_c)$ exhibited a notable increase of 26%, associated with an increase of 13.4 °C in the glass transition temperature (T_g).