After some general introductory remarks to the advantageous application of a twin screw extrusion to the melt spinning the lecture deals with investigations of elastomeric fibers consisting of ethylene-octene-copolymers which have been grafted by organosilanes and additionally blended with polybutylenterephthalates (PBT) and/or polyesterelastomers (PEE), all by means of a reactive twin screw extruder coupled with a side feeding single screw extruder in an online melt spinning process. It will be demonstrated that considerably improved mechanical properties of the elastomeric EO-fibers can be reached with this additional blend step. All spun fiber samples will be characterized regarding their structural and mechanical properties extensively. This work is a decisive expansion of our results published during the last two years regarding to the twin screw extrusion melt spinning [1 to 4].