Abstract: A polyamide yarn is disclosed which is at least about 85% by weight poly(.epsilon.-caproamide) and which has a relative viscosity of greater than 50, a tenacity of at least about 9.3 g/d, a dry heat shrinkage at 160.degree. C. of less than about 3 percent, a modulus of at least about 20 g/d, a toughness of at least about 240 g/d. %, a crystal perfection index of greater than about 82, and a long period spacing of greater than about 100 .ANG.. The process for making the yarn includes drawing of a feed yarn while heating to at least about 185.degree. C. in at least a final draw stage to a draw tension of at least 4.8 g/d, subsequently decreasing the tension while heating to at least about 185.degree. C. to produce a length decrease of between about 13.5 and about 30%, and cooling and packaging the yarn.

Abstract: A yarn comprised of a polyamide which is at least about 85% poly(hexamethylene adipamide) or poly(.epsilon.-caproamide) is disclosed which has a relative viscosity of greater than about 50, a tenacity of greater than about 11.0 g/d, a dry heat shrinkage at 160.degree. C. of not more than about 6.5 percent, a boil-off shrinkage of less than about 7%, a modulus of greater than about 35 g/d, a birefringence of greater than about 0.060, a differential birefringence D: .DELTA..sub.0.90-0.00, of greater than 0, and a sonic modulus of greater than about 90 g/d. The process for making the yarn includes drawing of a feed yarn while heating to at least about 185.degree. C. in at least a final draw stage to a draw tension of at least 3.8 g/d, subsequently decreasing the tension while heating to at least about 185.degree. C. to produce a length decrease of between about 2 and about 13.5, and cooling and packaging the yarn.

Abstract: A polyamide yarn is disclosed which is at least about 85% by weight poly(.epsilon.-caproamide) and which has a relative viscosity of greater than 50, a tenacity of at least about 9.3 g/d, a dry heat shrinkage at 160.degree. C. of less than about 3 percent, a modulus of at least about 20 g/d, a toughness of at least about 240 g/d.%, a crystal perfection index of greater than about 82, and a long period spacing of greater than about 100 .ANG.. The process for making the yarn includes drawing of a feed yarn while heating to at least about 185.degree. C. in at least a final draw stage to a draw tension of at least 4.8 g/d, subsequently decreasing the tension while heating to at least about 185.degree. C. to produce a length decrease of between about 13.5 and about 30%, and cooling and packaging the yarn.

Abstract: A polyamide yarn is disclosed which is at least 85% by weight poly(hexamethylene adipamide) and which has a relative viscosity of greater than 50, a tenacity of at least about 9.5 g/d, a modulus of at least about 30 g/d, a shrinkage at 160.degree. C. of less than about 2 percent, a crystal perfection index of greater than about 83, and a long period spacing of greater than about 105 .ANG.. The process for making the yarn includes drawing of a feed yarn while heating to at least about 190.degree. C. in at least a final draw stage to a draw tension of at least 3.8 g/d, subsequently decreasing the tension while heating to at least about 190.degree. C. to produce a length decrease of between about 13.5 and about 30%, and cooling and packaging the yarn.