Characterisation and Modelling of PLA Filaments and Evolution with Time

Area of Science:

• Materials Science
• Polymer Science
• Additive Manufacturing

Background:

• Polylactic acid (PLA) filaments are fundamental building blocks in material extrusion additive manufacturing.
• Detailed characterization of PLA filament properties, influenced by extrusion, is lacking.
• Understanding these properties is crucial for accurate modeling of 3D-printed structures.

Purpose of the Study:

• To comprehensively analyze the mechanical, thermal, physical, and fractographical properties of extruded PLA filaments.
• To establish a reference dataset for modeling additively manufactured PLA structures.
• To investigate the effects of natural aging, extrusion temperature, and tensile test speed on PLA filament properties.

Main Methods:

• Material extrusion of PLA filaments at 180 °C and 190 °C.
• Mechanical testing (tensile tests) at various crosshead speeds (10⁻¹ to 10² mm/min).
• Natural aging studies for up to one year.
• Thermal analysis including glass transition and enthalpic relaxation measurements.

Main Results:

• Higher extrusion temperature (190 °C) initially yielded better performance, but aging diminished differences.
• Mechanical properties showed a logarithmic increase with crosshead speed, aligning with the Eyring model.
• Natural aging significantly increased elastic modulus and yield strength, and elevated glass transition and enthalpic relaxation.

Conclusions:

• PLA filament properties are highly sensitive to extrusion conditions and aging.
• The Eyring and Kohlrausch-Williams-Watts models effectively describe the material's behavior under varying conditions.
• This detailed characterization provides essential data for precise modeling and application of 3D-printed PLA components.