experimental investigation on 4d printing of pet-g

In this work, for the first time, pet-g commercial filament is employed for 4d printing of novel shape memory polymer (smp). pet-g was found to be an amorphous smp with net points of tight-knitted physical entanglements decelerating the stress relaxation. printing parameters had a significant effect on the self-morphing behavior as well as shape and stress recovery. birefringence studies using polarized light microscopy (plm) revealed that the fused deposition modeling (fdm) process induces a higher pre-strain in the bottom layers than in the top ones, resulting in a downward self-bending. it was revealed that lower printing temperatures and higher printing speeds enhance the self-bending and shape recovery characteristics. all shape fixity ratios were higher than 82%, with a maximum of 95.83% for samples printed with ± 45 raster angles. the sample with the highest self-bending exhibited the maximum recovered stress of 1.24 mpa.