This project achieved significant progress in the development and validation of biodegradable multifilament yarns through extensive melt-spinning, material characterization, and environmental degradation testing. The results provide strong evidence for the technical feasibility and environmental relevance of replacing fossil-based synthetic fibers with biodegradable alternatives in textile applications.
A diverse portfolio of biodegradable polymers was selected for evaluation, including PLAs, PHAs, PBS, PGA, and PCL, along with copolymers such as PBAT, PBSA, PBST, PBEAS, PBSeT, and PLGA etc. These materials were subjected to rigorous screening to assess their processability, mechanical properties, and degradation behavior.
Melt-Spinning and Yarn Production:
Pilot-scale melt-spinning trials were conducted to produce continuous multifilament yarns from the selected polymers. Processing parameters—such as temperature, take-up speed, draw ratio, throughput etc. were optimized for each material to ensure stable filament formation. PLA, PBS, and PGA demonstrated particularly good spinnability, resulting in uniform yarns with acceptable tenacity and elongation. The yarns were collected on spools and prepared for further textile processing and testing. PHAs, and some copolymers e.g. PBSA, PBST, and PBAT faced challenges in the spinning process (mostly due to slow crystallization or low melt strength).
Mechanical and Thermal Characterization:
The produced yarns were tested for tensile strength, elongation at break, and Young’s modulus. While PLA and PGA-based yarns showed higher tensile strength, while PCL, PBS, and copolymer yarns were lower in tenacity and higher in elongation. Thermal analysis using DSC and TGA revealed insights into melting behavior, crystallinity, and thermal degradation profiles, critical for defining processing windows and end-use stability.
Abiotic Hydrolysis:
To evaluate polymer stability under abiotic conditions, hydrolysis experiments were conducted at controlled conditions using an NMR-assisted monomer identification method. Hydrolytic degradation, particularly of ester bonds, was significant in polymers such as PLA, PLGA, and PGA, which are known to undergo bulk erosion. On the other hand, the fast biodegradation of some polymers such as PHAs and cellulose is showing that they follow enzymatic hydrolysis pathway.
Biodegradation in Soil and Wastewater:
The biodegradation potential of the polymers was assessed under simulated environmental conditions, specifically in soil and wastewater environments. Testing followed standard protocols (e.g. ISO 17556, ISO 14851) and focused on CO2 evolution (soil) and BOD (wastewater), and physical disintegration (mesocosm). The results showed that PHAs have a high biodegradation rate (even faster than cellulose in some cases) although their abiotic hydrolysis rate is not significant (even slower than PLA). Afterward, some copolymers (especially non-aromatic and less crystalline) e.g. PBSA, PBEAS, PLGA, etc. had faster degradation. The next orders were for PCL and then PBS. The aromatic containing polymers such as PBSeT, and mostly PBAT were before PLA as the last one. Another result was achieved by testing different fibers, showing that the more orientation and crystallization in the fiber or yarn level, the slower the biodegradation rate. This was confirmed by testing fully drawn yarns (FDY) and partially oriented yarns(POY) of PGA and PBS versus each other and the polymer powder. The outcome was clear that polymer powders degraded faster than the POY and then FDY sample.
Key Insights and Conclusions:
The results demonstrate that biodegradable polymers can be effectively processed into multifilament yarns and used in textile applications while also offering measurable environmental benefits at their end-of-life. Material selection plays a critical role in balancing mechanical performance with biodegradability. PLA and PBS emerged as lead candidates due to their favorable spinning behavior and degradation profiles. The study also highlights the need for application-specific matching of polymer properties, as degradation kinetics vary with environmental conditions. Also addressing the durability in the textile application (considering the contradiction with the biodegradation and performance drop) is a key for prospect works.
Overall, the project’s outcomes contribute valuable technical data to guide material selection, regulatory frameworks, and industrial adoption of biodegradable yarns, supporting the broader transition to sustainable textiles.
