Melt-Spun P(3HB)/P(3HB-co-4HB) Monofilaments: Cyclic Loading Behavior and Fabrication into Textile Structures

Melt-spun polyhydroxyalkanoate monofilaments were successfully processed into woven and knitted textiles using industrial machinery, demonstrating their feasibility for textile applications. The filaments, composed of P-(3HB)/P-(3HB-co-4HB), exhibited an average tensile strength of ∼138 MPa and an elongation at break of ∼55%, with crystallinity of ∼30%. Cyclic loading of the filaments revealed pronounced hysteresis during the first cycle, which diminished in subsequent cycles. However, a relaxation time of 120 s was sufficient to reset the molecular conformational changes that occurred during the previous cycles. Furthermore, the incorporation of beta tricalcium phosphate (β-TCP) particles during melt spinning reduced tensile strength but improved thermal stability, enhancing processability. These findings highlight the potential of P-(3HB)/P-(3HB-co-4HB) monofilaments for sustainable textile applications requiring mechanical resilience and thermal robustness.