Abstract: This invention concerns a process for increasing the molecular weight and viscosity of polyamides and other condensation polymers, by first injecting an inert gas into the polymer melt at elevated pressure, then stripping the volatiles from the polymer through the application of reduced pressure, followed by holding the polymer at elevated temperatures long enough for the reaction to occur. Activators may be added to the polymer. Port areas used in the stripping zone, may be kept hot for continuous operation.

Abstract: Distribution of a fluid additive through multiple passages across the cross section of a pipe carrying molten/fluid polymer wherein the polymer flow is distributed across the cross section of the pipe provides uniform distribution of the fluid additive when the passages are directed in the downstream direction of flow and substantially parallel to the longitudinal axis of the pipe carrying the polymer. This device is advantageous for mixing of two or more fluids independent of the viscosity differences.

Abstract: An improved process for preparing polyamide hollow filaments wherein an N,N'-dialkyl polycarbonamide is melt blended with the molten fiber-forming polyamide prior to spinning into filaments. The polycarbonamide substantially decreases the collapsing of the voids which naturally occurs immediately .after spinning and before the filaments are completely cool.

Abstract: An improved process for preparing polyamide hollow filaments wherein an N,N'-dialkyl polycarbonamide is melt blended with the molten fiber-forming polyamide prior to spinning into filaments. The polycarbonamide substantially decreases the collapsing of the voids which naturally occurs immediately after spinning and before the filaments are completely cool.

Abstract: An improved process for melt spinning a pigmented hexamethylene adipamide fiber from a melt blend of a polymer and a colored pigment wherein the polymer is a random interpolyamide or a block polymer having two different difunctional recurring amide-forming moieties other than those which form hexamethylene adipamide is disclosed along with pigmented hexamethylene adipamide polymer fibers having tenacities greater than 7.5 or even 8 grams per denier.

Abstract: An improved process for melt-spinning a pigmented hexamethylene adipamide fiber from a melt blend of a polymer and a colored pigment wherein the polymer is a random interpolyamide or a block polymer having two different difunctional recurring amide-forming moieties other than those which form hexamethylene adipamide is disclosed along with pigmented hexamethylene adipamide polymer fibers having tenacities greater than 7.5 or even 8 grams per denier.

Abstract: A process for modifying the dyeability of polyamide polymers is disclosed, the process involving the addition of co-fed polyamide flake of the same type of polyamide as the base polyamide with the co-fed flake having a significant effect on the final dyeability. The additive flake comprises high- or low-amine-end polyamide flake which is mixed and melted with the base polyamide to adjust the total number of amine ends in the polymer, thereby controlling the polymer dyeability.

Abstract: An apparatus for on-line determination and control of the Flow Behavior Index of a molten polymer stream are disclosed along with methods for using the Index as a means for monitoring and controlling polymer quality. In particular, the Index may be used to monitor and control on-line the levels of branching in the polymer and the polymer's molecular weight distribution.

Abstract: Process and apparatus for on-line determination and control of the Flow Behavior Index of a molten polymer stream are disclosed along with methods for using the Index as a means for monitoring and controlling polymer quality. In particular, the Index may be used to monitor and control on-line the levels of branching in the polymer and the polymer's molecular weight distribution.

Abstract: Uniformity of properties of spun polyamide filaments is improved by treating flake polyamide with successive nitrogen gas streams, the first having a variable temperature and water content, and the second being dry but having a variable flow rate. Viscosity of the molten polyamide from a melter for the flake is determined by measuring differential pressure across a transfer pipe. The viscosity measurement is used by automatic control apparatus to control the flow rate of the second stream, and the moisture content of a make-up stream added to the first stream. The flow rate of the make-up stream is controlled to maintain the second stream within limits, and the temperature of the first stream is controlled to maintain the flow rates of the make-up and second streams within limits.