Mechanical performance and shape memory characteristics of 4D printed PCTG structures

Additive manufacturing (AM) enables the fabrication of complex, multifunctional structures, while integration with shape memory polymers (SMPs) extends this capability to 4D printing through time-dependent, stimulus-responsive behavior. However, commonly used SMPs like PLA are brittle at room temperature, limiting their use in load-bearing or deformable components. This study investigates poly(cyclohexylene dimethylene terephthalate glycol; PCTG), a largely unexplored but mechanically robust alternative, for 4D printing applications using cold programming. Using a Taguchi L27 design, we systematically examine the effects of five key printing parameters, that is, nozzle temperature, layer height, print speed, infill density, and raster angle on the tensile and flexural properties of 3D-printed PCTG. FTIR and DSC analyses confirm PCTG’s amorphous nature and glass transition temperature of ∼84 ° C. Mechanical testing reveals tensile strength up to 43 MPa, flexural modulus values ranging from 1.43 to 1.98 GPa, and high ductility. Cold-programed shape memory behavior is demonstrated via three-point bending at room temperature followed by thermal recovery. Shape recovery ratios reach up to 0.99, and shape fixity ratios up to 0.82 are achieved, depending on process conditions. Results highlight PCTG’s potential as a ductile, tunable SMP for advanced 4D printing, overcoming key limitations of conventional materials like PLA.