Elyas Soleyman - School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
Davood Rahmatabadi - School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
Majid Baniassadi - School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
Mostafa Baghani - School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran

In this work, for the first time, PET-G commercial filament is employed for ۴D 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 ۸۲%, with a maximum of ۹۵.۸۳% for samples printed with ± ۴۵ raster angles. The sample with the highest self-bending exhibited the maximum recovered stress of ۱.۲۴ MPa.

۴D printing; Self-morphing; PET-G; Amorphous shape memory polymer; Polarized light microscopy