Thermo-Mechanical Behavior and Strain Rate Sensitivity of 3D-Printed Polylactic Acid (PLA) below Glass Transition...

Area of Science:

• Materials Science
• Polymer Engineering
• Additive Manufacturing

Background:

• 4D-printed polylactic acid (PLA) is a promising smart material with shape memory capabilities.
• Understanding its thermomechanical behavior is crucial for designing functional applications.

Purpose of the Study:

• To investigate the thermomechanical properties of 4D-printed PLA under varying temperatures and strain rates.
• To determine the influence of these parameters on mechanical response and shape memory potential.

Main Methods:

• Characterization using tension, compression, and dynamic mechanical thermal analysis (DMTA).
• Thermo-mechanical compression tests conducted at temperatures below the glass transition temperature (T_g) and across a range of strain rates.
• Adiabatic tests with thermal imaging to assess self-heating effects.

Main Results:

• PLA's elastic modulus varies significantly between glassy (1045.7 MPa) and rubbery (1.2 MPa) phases, indicating shape memory potential.
• Yield stress is strongly dependent on strain rate and temperature, ranging from 110 MPa to 42 MPa.
• Higher strain rates (0.01-0.1 s^-1) induce self-heating, causing material softening.

Conclusions:

• 4D-printed PLA demonstrates significant strain rate and temperature sensitivity below its T_g (65 °C).
• The material exhibits notable shape memory potential due to its phase transition behavior.
• Self-heating at high strain rates impacts mechanical performance, necessitating consideration in application design.