Toward High-Performance Poly(l-lactide) Fibers via Tailoring Crystallization with the Aid of Fibrillar Nucleating Agent

As a sustainable alternative to conventional petrochemical-based polymers, biobased and biodegradable poly(l-lactide) (PLLA) exhibits tremendous application potential in the textile industry due to its attractive elastic recovery, moisture regain, and flammability. However, the commercial adoption of PLLA textile fibers still faces some hurdles mainly associated with their poor heat resistance (i.e., high thermal shrinkage or low dimensional stability) because the low crystallization rate makes PLLA difficult to crystallize during melt spinning. Herein, we report a simple but robust strategy to address this hurdle via simultaneously manipulating crystallinity and lamellae orientation with the aid of a highly active nucleating agent (NA) that can be completely dissolved in PLLA melt and reorganize into fine fibrils upon cooling. By taking full advantage of strong elongational flow field involved in the melt spinning, the NA fibrils with high nucleation efficiency on PLLA crystallization tend to align along the flow direction and subsequently serve as nucleation templates to induce the growth of kebab-like PLLA lamellae perpendicular to their long axis, finally forming large amounts of highly orientated crystal structure in melt-spun PLLA fibers. In this way, the crystallization manipulation imparts the PLLA fibers with an impressive combination of superior mechanical strength and heat resistance. Compared with neat PLLA fiber, a prominent increase of 78% in tensile strength and a substantial decline of 1069% in boiling water shrinkage are achieved in the fiber nucleated with 0.3 wt % NA. This work could open up an avenue toward the design and development of high-performance PLLA fibers by using fibrillar nucleating agent as a nucleation template to tailor effectively crystallization in the melt spinning process.