Melt-spun poly(lactic acid) fibers modified with soy fillers: Toward environment-friendly disposable nonwovens

Poly(lactic acid) (PLA) has a significant potential as a biodegradable polymer, but its high cost and slow biodegradability restrict its use in disposable products. This study establishes a novel route to accomplish both objectives by the addition of low-cost soy fillers into PLA, which reduced material cost and increased the degradation rate of resulting soy-PLA fibers. Due to partial thermal degradation of soy fillers at PLA melt temperature, they could be melt-compounded into PLA up to 5 wt%. Fine continuous fibers (D similar to 25-50 mu m) were successfully produced via melt spinning, and further melt-consolidated into prototypical nonwovens. The tensile strength of soy-PLA fibers containing soy reside and soy flour were 56 +/- 9 and 44 +/- 5 MPa, respectively. Although slightly lower than that of neat PLA fibers (74 +/- 2 MPa), the fibers possessed adequate tenacity for use as nonwoven fabrics. Fiber modulus remained unaffected at about 2.5 GPa. The soy-PLA fibers displayed a relatively rough exterior surface and provided a natural-fiber feel. The overall degradation of soy-PLA fibers was accelerated about 2-fold in a basic medium due to the preferential dissolution of soy that led to increased surface area within the PLA matrix indicating their potential for use in biodegradable nonwovens.