Abstract: An entangled multifilament yarn made from high strength filaments having a tenacity of at least about 7 g/d, a tensile modulus of at least about 150 g/d and an energy-to-break of at least about 8 J/g. The yarn is used to make ballistic resistant articles.

Abstract: By poststretching, at a temperature between about 135.degree. and 160.degree. C., a polyethylene fiber, which has already been oriented by drawing at a temperature within 5.degree. C. of its melting point, an ultra high modulus, very low creep, low shrink, high tenacity polyolefin fiber having good strength retention at high temperatures is obtained. The poststretching can be in multiple stages and/or with previous annealing. The poststretching should be done at a draw rate of less than 1 second.sup.-1. Tensile modulus values over 2,000 g/d for multifilament yarn are consistently obtained for ultrahigh molecular weight-polyethylene, with tensile strength values above 30 g/d while at the same time dramatically improving creep (at 160.degree. F. (71.1.degree. C.) and 39,150 psi load) by values at least 25% lower than fiber which has not been poststretched. Shrinkage is improved to values less than 2.5% of the original length when heated from room temperature to 135.degree. C.

Abstract: An article including a woven fabric for impeding the passage of air, the fabric having an air permeability of less than about 15 cfm/ft.sup.2 and including at least one multifilament yarn having a longitudinal axis, the yarn being made of high strength filaments having a tenacity of at least about 7 g/d, a tensile modulus of at least about 150 g/d and an energy-to-break of at least about 8 J/g. Preferably, the high strength filaments are extended chain polyethylene.

Abstract: This invention is a cut resistant article comprising a cut resistant jacket surrounding a less cut resistant member. The jacket comprises a fabric of yarn and the yarn consists essentially of a high strength, longitudinal strand having a tensile strength of at least 1 GPa. The strand is wrapped with another fiber or the same fiber. In another embodiment, the invention is a highly cut resistant yarn of at least two nonmetallic fibers. One fiber is inherently cut resistant like high strength polyethylene, polypropylene or aramids. The other fiber in the yarn has a high level of hardness.

Abstract: A method of extracting a material from a continuous running length of fiber comprising continuously moving the fiber through a conduit while simultaneously flowing a solvent for the material through the conduit with the conduit having a length and cross sectional area sufficient to facilitate extraction of the desired amount of the material. The flow is countercurrent to the movement of the fiber.

Abstract: This invention is an apparatus and method of extracting a material from a continuous running length of fiber comprising continuously moving the fiber through a conduit while simultaneously flowing a solvent for the material through the conduit with the conduit having a length and cross sectional area sufficient to facilitate extraction of the desired amount of the material. The flow is preferred to be countercurrent to the movement of the fiber.

Abstract: There is provided by this invention a process for the production of high molecular weight linear polyethylene terephthalate condensation polyesters which are useful especially for preparing specialty fibers which have excellent resistance to degradation so that they can be used in such commercial articles as paper making machine fabric, industrial belting, etc. The improved high molecular weight linear polyethylene terephthalate condensation polyester specialty fibers are characterized by improved hydrolytic stability and by reduction in the free carboxyl content so as to have a carboxyl concentration of less than about 6 gram equivalents per 10.sup.6 grams of the polyester.