PLA Staple Fiber

1. Bio-based feedstock route: the chain starts from starch-rich biomass such as corn, sugarcane, and cassava. After saccharification, selected lactic-acid bacteria ferment the sugars into high-optical-purity L-lactic acid, which is condensed into a prepolymer and thermally cracked into lactide, the cyclic dimer of lactic acid. Catalytic ring-opening polymerization (ROP) of the purified lactide then yields high-molecular-weight poly-L-lactic acid resin -- the mainstream route to fiber-grade PLA because it delivers high, narrow-distribution molecular weight with excellent reproducibility.

2. Melt spinning: PLA is a thermoplastic and can be melt-spun on equipment closely resembling PET lines. Because the ester bonds along the chain hydrolyze rapidly in the presence of heat and trace moisture, the resin must first be vacuum-dried to ppm-level water content, and melting is held within a narrow window of roughly 190-230 ℃. Extruded filaments are quenched, multi-stage drawn, crimped, heat-set, and cut into staple -- an entirely solvent-free, environmentally clean process.

3. Structure-driven properties: the flexible, moderately crystalline PLA chain gives the fiber a density of only about 1.25 g/cm3; its ester groups and pendant methyl groups bring natural bacteriostatic behavior and reduced flammability (limiting oxygen index around 26%, with low smoke emission); surface grooves and micro-voids create capillary moisture channels. Under the hot, humid conditions of industrial composting (58 ℃ and above), microorganisms hydrolyze the amorphous regions step by step until the fiber fully converts to carbon dioxide and water, re-entering the photosynthetic carbon cycle of plants.