Abstract: A multi-filament poly(trimethylene terephthalate) yarn is provided. The poly(trimethylene terephthalate) yarn has a crystal orientation function of at least 0.6 and an elongation at break of between 65% and 110%. A process for producing the yarn is also provided in which poly(triemethylene terephthalate) is melt-spun into a multi-filament yarn, the yarn is cooled to a yarn temperature of less than 50° C., and the cooled yarn is taken-up at a take-up speed of at least 3500 m/min while maintaining the temperature of the yarn at a yarn temperature of less than 50° C.

Abstract: Provided is a molecular composite comprising a rigid-rod aromatic heterocyclic polymer, a flexible, coil-like thermoplastic polymer and a thermosetting polymer.Also provided is a method for fabricating a molecular composite film or fiber which comprises the steps of forming a biphasic, stir opalescent solution of a rigid-rod aromatic heterocyclic polymer, a thermoplastic polymer, a thermosetting polymer and a solvent which is common to the three polymers, adding solvent to the solution until the solution becomes isotropic and stir opalescence has ceased to determine the critical concentration of polymers in the solvent, adding additional solvent to the solution so that the polymer concentration is below the critical concentration, extruding the solution into a non-solvent for the polymers to form the desired film or fiber, drying the film or fiber and hot drawing the film or fiber at a temperature above the Tg of the thermoplastic, but below the polymerization temperature (Tpoly) of the thermosetting resin.

Abstract: Provided is a molecular composite comprising a rigid-rod aromatic heterocyclic polymer, a flexible, coil-like thermoplastic polymer and a thermosetting polymer.Also provided is a method for fabricating a molecular composite film or fiber which comprises the steps of forming a biphasic, stir opalescent solution of a rigid-rod aromatic heterocyclic polymer, a thermoplastic polymer, a thermosetting polymer and a solvent which is common to the three polymers, adding solvent to the solution until the solution becomes isotropic and stir opalescence has ceased to determine the critical concentration of polymers in the solvent, adding additional solvent to the solution so that the polymer concentration is below the critical concentration, extruding the solution into a non-solvent for the polymers to form the desired film or fiber, drying the film or fiber and hot drawing the film or fiber at a temperature above the Tg of the thermoplastic, but below the polymerization temperature (Tpoly) of the thermosetting resin.