Recycled poly(ethylene terephthalate) (RPET) multifilament yarns are used in carpet manufacturing as a way to reduce plastic waste. The conventional RPET carpet is however susceptible to bacterial accumulation. As a result, this research experimentally doped RPET with nano-structure titanium dioxide (nano-TiO2) to produce RPET/nano-TiO2 bicomponent multifilament yarns with antibacterial property. The experimental multifilament yarn structure consisted of two parts: neat RPET core and RPET/nano-TiO2 shell. The nano-TiO2 content in the shell was varied between 1 and 3 wt% and the core/shell (C/S) ratios between 90/10, 70/30, and 50/50 w/w. The effects of C/S ratio and nano-TiO2 content on the mechanical and antibacterial properties of bicomponent multifilament yarns were determined. The experimental results indicated that the C/S ratio had no effect on the tenacity and elongation at break. Meanwhile, the tenacity and elongation at break of bicomponent fibers increased with nano-TiO2 content in the shell. The TiO2-doped RPET bicomponent yarns effectively inhibited the growth of Escherichia coli and Staphylococcus aureus. The 90/10 bicomponent multifilament fiber with 3 wt% TiO2 achieved the highest antibacterial activity. The very high antibacterial activity was attributable to greater deposition of nano-TiO2 particles near and on the shell surface.
