Shape Memory Behaviour of PMMA-Coated NiTi Alloy under Thermal Cycle

Sneha Samal; Olga Kosjakova; David Vokoun; Ivo Stachiv

doi:10.3390/polym14142932

Shape Memory Behaviour of PMMA-Coated NiTi Alloy under Thermal Cycle

Polymers (Basel). 2022 Jul 20;14(14):2932. doi: 10.3390/polym14142932.

Authors

Sneha Samal¹, Olga Kosjakova¹, David Vokoun¹, Ivo Stachiv¹

Affiliation

¹ FZU-Institute of Physics of Czech Academy of Science, Prague 8, Na Slovance 1999/2, 18221 Prague, Czech Republic.

Abstract

Both poly(methyl methacrylate) (PMMA) and NiTi possess shape memory and biocompatibility behavior. The macroscale properties of PMMA-NiTi composites depend immensely on the quality of the interaction between two components. NiTi shape memory alloy (SMA) and superelastic (SE) sheets were spin coated on one side with PMMA. The composite was prepared by the spin coating method with an alloy-to-polymer-thickness ratio of 1:3. The bending stiffness and radius of curvature were calculated by using numerical and experimental methods during thermal cycles. The experimental radius curvatures in actuation have good agreement with the model. The change in shape results from the difference in coefficients of thermal expansion between PMMA and NiTi. Actuation temperatures were between 0 and 100 °C for the SMA-PMMA composite with a change in curvature from 10 to 120 mm with fixed Young's modulus of PMMA at 3 GPa, and a change in Young's modulus of NiTi from 30 to 70 GPa. PMMA-NiTi composites are useful as actuators and sensor elements.

Keywords: NiTi; PMMA; curvature; radius; shape recovery; thermal cycles.

Grants and funding

This research was funded by Operational Program Research, Development, and Education financed by European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports (Project No. SOLID21-CZ.02.1.01/0.0/0.0/16_019/0000760) and by the Czech Science Foundation under project no. 21-12994J and no. 22-14387J.