Modifying crystallisation behaviour to improve forming quality and mechanical properties of 3D-printed semicrystalline polymers
摘要
3D printed polypropylene (PP) specimens usually show warpage deformation due to PP’s unexpected crystallisation behaviour, e.g. dense and coarse α crystals form and crystals are unevenly distributed, both of which limits widespread applications. In this study, modified PP particles were prepared using a β-nucleating agent to modify the PP crystallisation behaviour. The effects on the printing quality and mechanical properties of 3D printed PP parts were investigated. Compared to the unmodified sample (PP0), the modified PP with a 0.3% addition of the β-nucleating agent (PP3) exhibited the best overall performance: PP3 had the highest crystallinity and crystallisation induction efficiency, with a relative β-crystal content of 80.8% and a crystallisation temperature reduced by 3.5 °C. The PP3 printed specimens exhibited the least warpage (2.4 mm) and shrinkage (2.8 mm) deformation, with reductions of 57% and 26%, respectively. Additionally, flow properties of PP3 were comparatively improved, showing the lowest apparent viscosity (1.21 × 104 mPa s) and the highest melt index (1.8 g/10 min), which further reduced the internal porosity of the printed specimens by 78%. Moreover, PP3’s Young’s modulus, yield strength, and fracture strain were significantly increased compared to the unmodified sample PP0.