Layer-dependent properties of material extruded biodegradable Polylactic Acid

Area of Science:

• Materials Science
• Biomaterials Engineering
• Additive Manufacturing

Background:

• Polylactic acid (PLA) is a widely used biodegradable polymer in additive manufacturing for biomedical devices.
• Layer-by-layer fabrication in additive manufacturing can lead to variations in material properties due to thermal history and degradation.
• Understanding the impact of layer number on PLA properties is crucial for optimizing device performance.

Purpose of the Study:

• To investigate how the number of layers influences the mechanical, thermal, and molecular weight properties of 3D printed polylactic acid.
• To explore the relationships between these properties as a function of layer count.
• To determine the optimal number of layers for achieving desired material characteristics.

Main Methods:

• Preparation of polylactic acid specimens with varying layer numbers (1 to 10 layers) using additive manufacturing.
• Characterization of specimens through mechanical testing (tensile strength, Young's Modulus, strain) and thermal analysis (degree of crystallinity).
• Analysis of molecular weight changes in relation to the number of deposited layers.

Main Results:

• Degree of crystallinity decreased significantly from 8% to 0.5% as the number of layers increased.
• Molecular weight increased with the number of layers, approaching bulk material values.
• Ultimate tensile strength and strain increased with layer count, while Young's Modulus decreased.
• No significant differences in mechanical or thermal properties were observed between 5- and 10-layer specimens.

Conclusions:

• The number of layers in additive manufactured PLA impacts its structural integrity and material characteristics.
• Layer-dependent variations in cooling rates and molecular weight influence mechanical performance.
• For optimal mechanical and thermal properties in PLA devices, a minimum of 5 layers is suggested, beyond which improvements are marginal.