4D-Printed Resins and Nanocomposites Thermally Stimulated by Conventional Heating and IR Radiation

Abstract

The shape memory (SM) capabilities of nanocomposites based on two
\nphotocurable acrylated/methacrylated resins, doped with carbon nanotubes (CNTs), and
\nmanufactured by digital light processing 3D printing were investigated. The mechanical
\nproperties and glass transition temperature (Tg) can be tailored in a broad range by varying
\nthe weight ratio of the two resins (Tg ranging from 15 to 190 ?C; Young?s modulus from
\n1.5 to 2500 MPa). Shape fixity (SF) and recovery (SR) ratios are strongly influenced by the
\ntemperature being significantly higher at temperatures close to the Tg. The results confirm
\nthat the SF strongly depends on the stiffness of chain segments between cross-linking
\npoints, whereas the SR mainly depends on the cross-link density of the network. CNT
\naddition barely affects the SF and SR in the conventional oven, whereas the recovery speed
\nusing IR heating is significantly increased for the doped nanocomposites due to their higher
\nIR absorbance.