Investigating the Effect of Poly (D L-Lactic Acid) Molecular Weight on the Shape Memory Parameters: A Molecular Dynamics Study

Subject Areas :

Mohammad Amini ¹ (MSc. in Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran.)
Abbas Montazeri ² (Associate Professor, Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran.)

Received: 2021-12-09 Accepted : 2022-03-06 Published : 2022-06-22

Keywords: Molecular dynamics simulation, Molecular weight, Glass transition temperature, Polylactic Acid, Shape Memory Property,

Abstract :

Shape memory polymers are a subset of smart materials that can regain their original shape after a temporary deformation. In recent years, these polymers have been vastly utilized in many industries (especially biomedical). The main purpose of this study was to find the influence of the polymer molecular weight on the various shape memory parameters. Additionally, the mechanisms governing the shape memory behavior of polymers are thoroughly studied. Calculating the glass transition temperature and exploring its role on the shape memory behavior of polymeric materials are the other objectives of the current research. In this study, all models were built via Materials Studio and all the simulations were carried out using LAMMPS software. Based on the obtained results, the glass transition temperature of polymer increases with increasing the degree of polymerization. The attempts made to achieve an optimal microstructure revealed that the shape fixity parameter increases from 90% to 94% with increasing the molecular weight from 36000 g/mol to 108000 g/mol. In contrast to the shape fixity, the shape recovery parameter follows a descending trend with increasing the molecular weight. This is attributed to an increase in the ratio of the fixed phase to its reversible counterpart.

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