Abstract: A process for production of a dimensionally stable drawn polyethylene terephthalate multifilament yarn having filaments of at least 2.5 denier per filament comprising the steps of:a) extruding a polyethylene terephthalate polymer melt through a spinnerette having a plurality of extrusion orifices to form filaments;b) advancing the extruded multifilament yarn first through a delay zone then through a quenching zone to solidify the filaments in a controlled manner;c) withdrawing the solidified multifilament yarn from the quenching zone at a desired spinning speed V;whereby steps a) through c) are performed under conditions to form a partially-oriented multifilament yarn having a undrawn birefringence (.DELTA.n.sub.u) of at least 0.020 and wherein .DELTA.n.sub.u =R.sub.f V.sup.2.0 IV.sup.2.4 where IV is the intrinsic viscosity of the undrawn yarn and is at least 0.80 and R.sub.f is at least 9.0.times.10.sup.-3 ; thend) hot drawing the partially-oriented multifilament yarn.

Abstract: An apparatus for commingling yarn. The apparatus has an inner body having a yarn passageway with a diameter of about 1/4 inch to 5/16 inch. There are orifices through which a high pressure fluid such as air pass to the yarn passageway. The orifices have a diameter of about 0.060 to 0.80 inches.

Abstract: A low shrinkage, dimensionally stable, polyester fiber is produced by a process which involves conditions of continuously spinning and drawing filaments wherein the filaments are passed through a steam impinging draw point localizing jet (25) at a temperature of about 482.degree. C. to 580.degree. C. to thereby heat the filaments substantially immediately above their second order transition temperature. The low shrinkage polyester fibers are particularly useful in the preparation of tires and industrial products, including industrial belts, conveyor belts, and reinforced elastomeric structures.

Abstract: A low shrinkage, dimensionally stable, polyester industrial fiber is produced by a process which involves conditions of continuously spinning and drawing filaments wherein the filaments are passed through a steam impinging draw point localizing jet (25) at a temperature of about 460.degree. C. to 580.degree. C. to thereby heat the filaments substantially immediately above their second order transition temperature. The low shrinkage polyester fibers are particularly useful in the preparation of industrial products, including industrial belts, conveyor belts, and reinforced elastomeric structures.