Formation and Investigation of Mechanical, Thermal, Optical and Wetting Properties of Melt-Spun Multifilament Poly(lactic acid) Yarns with Added Rosins

One method for adding enhancing properties to textile materials is the insertion of natural ingredients into the textile products during the manufacturing or finishing process. The aim of this research is to investigate the formation of biodegradable melt-spun multifilament Poly(lactic acid) (PLA) yarns with different contents (i.e., 5%, 10%, and 15%) of natural material–rosin, also known as colophony. In this study, multifilament yarns were successfully formed from PLA and a natural substance–pine rosin by melt-spinning them at two different draw ratios (i.e., 1.75 and 2.75). The results indicated that a 1.75 draw ratio caused the formation of PLA and PLA/rosin yarns that were brittle. The presence of rosin (i.e., 5% and 10%) in multifilament yarns decreased the mechanical properties of the PLA/rosin melt-spun multifilament yarns’ tenacity (cN/tex), breaking tenacity (cN/tex), and tensile strain (%) and elongation at break (%) and increased absorbance in the entire UV region spectra. In addition, the melting point and degree of crystallinity decreased and there was an increase in the wetting angle compared with pure PLA multifilament. The investigation of melt-spun yarns with Raman spectroscopy proved the presence of rosin in PLA melt-spun yarns.