Recycled plastic filament made from post‐consumer expanded polystyrene and polypropylene for fused filamant fabrication

This research focused on developing recycled polymer blend filament from post‐consumer expanded polystyrene and single‐use polypropylene container for fuse filament fabrication (FFF). In this work, recycled polystyrene (rPS)/recycled polypropylene (rPP) blend was extruded into filament for FFF printing. The increase in printing temperature obviously reduced the air gaps and improved the interlayer adhesion. However, the printed specimen only exhibited optimum tensile strength at printing temperature of 230°C. The printed specimens with rPS/rPP at 80/20 blend ratio showed the lowest tensile strength due to poor printed layers adhesion caused by incompatibility of polymer blend. However, printed specimens with rPS/rPP at 50/50 blend ratio could achieve optimum strength of 32 MPa. The micrographs proved that the voids in printed specimen were smaller or absent when the printing temperature and rPP content in the blend was increased. This means that the increase in print temperature and rPP content displayed a positive effect on the printed specimens. The effect of blend ratio had significantly increased melt flow and crystallinity of rPS/rPP blend when the rPP content was increased in the blend. However, the increase of melt flow and crystallinity led to noticeable warpage on the printed specimen.