Process-Property Relationships for Melt-Spun Poly(lactic acid) Yarn

Area of Science:

• Polymer Science
• Materials Engineering
• Biomaterials

Background:

• Poly(lactic acid) (PLA) is a versatile biomaterial valued for its biocompatibility and biodegradability.
• PLA's susceptibility to hydrolytic and thermal degradation during melt processing necessitates careful control of processing parameters.
• Achieving optimal yarn properties requires balancing processing conditions to prevent premature degradation.

Purpose of the Study:

• To investigate the impact of melt-spinning parameters on the mechanical and physicochemical properties of PLA yarn.
• To establish process-property relationships for extruded PLA yarn.
• To identify optimal processing conditions for desired yarn characteristics while minimizing degradation.

Main Methods:

• Melt-spinning of PLA under varying conditions including melt temperature, spinneret throughput, take-up speed, draw ratio, and drawing temperature.
• Characterization of resulting PLA yarn properties: yarn size (linear mass density), tenacity, elongation at break, crystallinity, and molecular weight.
• Analysis of process-induced degradation through molecular weight reduction.

Main Results:

• PLA yarn properties varied significantly with processing parameters, with yarn size ranging from 6.2 to 101.6 tex, tenacity from 2.5 to 34.1 gf/tex, and elongation at break from 4 to 480%.
• Crystallinity ranged from 14.6% to 62.2%, indicating significant structural differences based on processing.
• Molecular weight reduction due to process-induced degradation varied from 7.6% to 20.5% across different parameter combinations.

Conclusions:

• Melt-spinning parameters critically influence PLA yarn properties, enabling tailored characteristics.
• Controlling parameters like temperature and draw ratio is essential to achieve desired yarn performance and mitigate degradation.
• This research provides insights for optimizing PLA yarn extrusion for specific applications.