Abstract: Synthetic plastic fibers are enhanced by inclusions therein of micro-polyester particles (4), preferably sized or otherwise optimized to enhance surface (10) characteristics (abrasion resistance, hydrophilicity, coating receptiveness, increase dullness), reduce UV degradation. The synthetic plastic matrix is preferably polyester but can be any synthetic plastic. The invention is preferentially implemented in multi-component fibers (e.g. core (6)-sheath (8) bi-component fibers (3)) with the inclusions entirely or primarily in one or some, but not all such components. The PTFE inclusions, sizing, concentration, morphology can be adjusted to optimize their enhancing effects, reduce costs and enhance throughput of fiber production. Co-inclusions can be made with the PTFE including anti-microbial and/or coloring agents and with synergistic effects.

Abstract: Rectangular or round spinning nozzle packs for extruding thermoplastic filaments each have both melt channels and orifices for the higher melting polymer compound and also melt channels with orifices through which is passed a polymer compound that melts at a temperature 5 to 50.degree. C. lower. Variously designed insulation channels thermally separate these melt channels, which are operated at different temperatures.