Effect of remelting post-processing on the impact strength of polypropylene parts printed by fused deposition modeling

Fused deposition modeling (FDM) is a convenient rapid prototyping technology widely employed in the fields of education, medicine, and industry. However, enhancing interlayer bonding strength in the Z-axis direction remains a critical challenge for FDM-printed parts. Polypropylene (PP), a material widely used in traditional manufacturing, has received limited attention within the FDM field, particularly regarding post-processing techniques to enhance mechanical properties. To address this gap, we investigated the effect of remelting post-processing on the Charpy impact strength of PP printed parts. This study examined the influence of two factors: line width (0.4, 0.6, and 0.8 mm) and remelting temperatures (190, 195, 200, 205, and 210 degrees C). Mechanical testing revealed a non-monotonic relationship between impact strength and remelting temperature, with strength peaking at 200 degrees C before decreasing. Morphological analysis revealed that post-processing led to anisotropic dimensional changes, indicating preferential deformation in specific directions. Thermogravimetric analysis (TGA) and scanning electron microscope (SEM) images confirmed that reconstruction and oxidative degradation occur simultaneously during the remelting process, ultimately affecting the appearance and performance of the sample. Notably, samples with a 0.4 mm line width, remelted at 200 degrees C, displayed a threefold increase in impact strength compared to unprocessed samples.