Polyethylene solutions are extruded through a multi-orifice spinneret into a cross-flow gas stream to form a fluid product. The fluid product is stretched at a temperature at which a gel will form at a stretch ratio of at least 5:1 over a length of less than about 25 mm with the cross-flow gas stream velocity at less than about 3m/min. The fluid product is quenched in a quench bath consisting of an immiscible liquid to form a gel. The gel is stretched. The solvent is removed from the gel to form a xerogel and the xerogel product is stretched in at least two stages to produce a polyethylene yarn characterized by a tenacity of at least 35g/d, a modulus of at least 1600 g/d and a work to break of at least 65 J/g. The yarn is further characterized by having greater than about 60 % of a high strain orthorhombic crystalline component and, optionally, a monoclinic crystalline component greater than about 2 % of the crystalline content. Composite panels made with these yarns exhibit excellent ballistic resistance, e.g., SEAC of 300J-m2/Kg or higher against .38 caliber bullets using test procedure NILECJ-STD-0101.01. A ballistic resistant composite panel is provided comprising a polyethylene multi-filament yarn having a tenacity of at least about 35 g/d, a modulus of at least 1600 g/d, a work-to-break of at least about 65 J/g wherein the yarn has greater than about 60 % of a high strain orthorhombic crystalline component and the yarn has a monoclinic crystalline component greater than about 2 % of the crystalline content.

High tenacity, high modulus filament

By poststretching, at a temperature between about 135° and 160° C., a polyethylene fiber, which has already been oriented by drawing at a temperature within 5° 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 -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° F. (71.1° 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° C. Performance at higher temperature is improved by about 15° to 25° C.

Very low creep, ultra high moduls, low shrink, high tenacity polyolefin fiber having good strength retention at high temperatures and method to produce such fiber

Solutions of intermediate molecular weight polymers from about 200,000 to about 4,000,000, such as polyethylene, in a relatively non-volatile solvent are extruded through an aperature at constant concentration and thereafter stretched at a ratio of at least about 3:1 prior to cooling to form a first gel. The first gels are extracted with a volatile solvent to form a second gel, and the second gel is dried to form a low porosity xerogel. Stretching occurs with any one or more of the first gel, second gel or xerogel. The polyethylene products produced by our process include products having a molecular weight between about 200,000 and about 4,000,000 a tenacity of at least about 13 grams/denier, a modulus of at least about 350 gram/denier, a porosity of less than 10% by volume, a crystalline orientation function of at least about 0.95, and a main melting temperature of at least about 140° C.

Shaped polyethylene articles of intermediate molecular weight and high modulus

The invention relates to a process for making high-performance polyethylene multi-filament yarn comprising the steps of making a solution of ultra-high molar mass polyethylene in a solvent; spinning of the solution through a spinplate containing a plurality of spinholes into an air-gap to form fluid filaments, while applying a draw ratio DRfluid; cooling the fluid filaments to form solvent-containing gel filaments; removing at least partly the solvent from the filaments; and drawing the filaments in at least one step before, during and/or after said solvent removing, while applying a draw ratio DRsolid, wherein in a draw ratio DRfluid=DRsp×DRag of at least 50 is applied, wherein DRsp is the draw ratio in the spinholes and DRag is the draw ratio in the air-gap, with DRsp greater than 1 and DRag at least 1. The invention further relates to a spinplate having spinholes of specific geometry.

Process for making high-performance polyethylene multifilament yarn

The present invention is an improved impact resistant composite and helmet made thereof. The helmet comprises an impact resistant composite shell. The composite shell comprises a plurality of prepreg packets. Each prepreg jacket comprises at least about 2 and preferably 5 to 20 prepreg layers. There are from 2 to 50 and preferably 5 to 20 prepreg packets. Each prepreg layer comprises a plurality of unidirectional coplanar fibers embedded in a polymeric matrix. The fibers of adjacent layers in the prepreg packets are at an angle of from 45° to 90°, preferably 60° to 90°, more preferably 80° to 90° and most preferably about 90° from each other. The angle of the fiber in alternate layers is preferably, subtantially the same.

Impact resistant helmet

Solutions of ultrahigh molecular weigh polymers such as polyethylene in a relatively non-volatile solvent are extruded through an aperture (25) at constant concentration through the aperture and cooled to form a first gel of indefinite length (33) The first gels are extracted (D) with a volatile solvent to form a second gel (41) and the second gel is dried (E) to form a low porosity xerogel (47) The first gel, second gel or xerogel, or a combination, are stretched (F) Among the products obtainable are polyethylene fibers of greater than 38 or even 40 g/denier tenacity and of modulus greater than 1000 or even 1600 or 2000 g/denier

Process for producing high tenacity, high modulus crystalline thermoplastic article and novel product fibers

High tenacity, high modulus, cyrstalline thermoplastic fibres

Shaped polyethylene articles

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Shaped polyethylene articles of intermediate molecular weight and high modulus

Process for producing high tenacity, high modulus crystalline thermoplastic article and novel product fibers

High tenacity, high modulus, cyrstalline thermoplastic fibres

Shaped polyethylene articles