Development of isotactic polypropylene-based 3D printing materials with good dimensional accuracy and excellent impact properties

The main challenge of fused deposition modeling (FDM) is the limited variety of commercially available semicrystalline polymer materials. Isotactic polypropylene (iPP), with a fast crystallization rate and high crystallinity, tends to undergo extensive volumetric shrinkage during the FDM process, further inducing severe deformation and poor dimensional accuracy in 3D-printed parts. This study aims to develop desirable iPP-based materials for the FDM technique through physically blending iPP and thermoplastic polyester elastomer (TPEE). TPEE retards the nonisothermal crystallization ability of iPP, as indicated by the significant decrease in crystallinity (Xc) from 47.7% for neat iPP to 28.5% for the iPP blend at a weight ratio of 30/70. The suppressed crystallization behavior accounts for a drastic decrease in the warpage degree of the 3D-printed parts. The greater the content of TPEE is, the lower warpage the 3D-printed parts have. Additionally, the presence of TPEE slightly influences the shear viscosity of iPP. As a result, iPP blends exhibit excellent extrudability during a typical FDM process. TPEE also enhances the impact strength of 3D-printed parts by 168% compared to that of injection-molded iPP. Taken together, the iPP blends developed in this work are promising FDM feedstock materials with good dimensional accuracy and excellent impact strength.