Processes for making high-performance polyethylene multi-filament yarn are disclosed which include the steps of a) making a solution of ultra-high molar mass polyethylene in a solvent; b) spinning of the solution through a spinplate containing at least 5 spinholes into an air-gap to form fluid filaments, while applying a draw ratio DR.sub.fluid; c) cooling the fluid filaments to form solvent-containing gel filaments; d) removing at least partly the solvent from the filaments; and e) drawing the filaments in at least one step before, during and/or after said solvent removing, while applying a draw ratio DR.sub.solid of at least 4, wherein in step b) each spinhole comprises a contraction zone of specific dimension and a downstream zone of diameter Dn and length Dn with Ln/Dn of from 0 to at most 25, to result in a draw ratio DR.sub.fluid=DR.sub.sp*DR.sub.ag of at least 150, wherein DR.sub.sp is the draw ratio in the spinholes and DR.sub.ag is the draw ratio in the air-gap, with DR.sub.sp being greater than 1 and DR.sub.ag at least 1. High-performance polyethylene multifilament yarn, and semi-finished or end-use products containing said yarn, especially to ropes and ballistic-resistant composites, are also disclosed.

Processes for making high-performance polyethylene multi-filament yarn are disclosed which include the steps of a) making a solution of ultra-high molar mass polyethylene in a solvent; b) spinning of the solution through a spinplate containing at least 5 spinholes into an air-gap to form fluid filaments, while applying a draw ratio DR.sub.fluid; c) cooling the fluid filaments to form solvent-containing gel filaments; d) removing at least partly the solvent from the filaments; and e) drawing the filaments in at least one step before, during and/or after said solvent removing, while applying a draw ratio DR.sub.solid of at least 4, wherein in step b) each spinhole comprises a contraction zone of specific dimension and a downstream zone of diameter Dn and length Dn with Ln/Dn of from 0 to at most 25, to result in a draw ratio DR.sub.fluid=DR.sub.sp*DR.sub.ag of at least 150, wherein DR.sub.sp is the draw ratio in the spinholes and DR.sub.ag is the draw ratio in the air-gap, with DR.sub.sp being greater than 1 and DR.sub.ag at least 1. High-performance polyethylene multifilament yarn, and semi-finished or end-use products containing said yarn, especially to ropes and ballistic-resistant composites, are also disclosed.

The invention relates to an elastic composite structure, which is intended for use as a flexible, pliable and thin film structure in the manufacture of a 2- or 3-dimensional product, particularly for providing mechanical protection against cutting, puncturing and/or the like. The composite structure comprises firstly an elastomer system (1), which is constituted by at least one PUR- (polyurethane resin), PUD- (polyurethane dispersion), SI- (silicone) based elastomer material and/or the like, and secondly by a mechanically durable reinforcer system (2), such as a fabric, weave or knit structure (2a) made from one or more flexible hybrid yarns, an oriented flake reinforcement structure (2c) made from laminated flakes (y), and/or the like. The invention relates also to an elastic composite structure, which is intended for the above application and which comprises a reinforcement system (2) for reinforcing the same mechanically against cutting, puncturing and/or the like. In this respect, the composite structure's reinforcement system (2) is manufactured as a flake reinforcement composition, consisting of hard organic and/or inorganic components (y) and comprising at least one co-laminated hard polymer layer and an elastomer matrix (2; 2b) applied integrally in contact therewith.

Processes for making high-performance polyethylene multi-filament yarn are disclosed which include the steps of a) making a solution of ultra-high molar mass polyethylene in a solvent; b) spinning of the solution through a spinplate containing at least 5 spinholes into an air-gap to form fluid filaments, while applying a draw ratio DR.sub.fluid; c) cooling the fluid filaments to form solvent-containing gel filaments; d) removing at least partly the solvent from the filaments; and e) drawing the filaments in at least one step before, during and/or after said solvent removing, while applying a draw ratio DR.sub.solid of at least 4, wherein in step b) each spinhole comprises a contraction zone of specific dimension and a downstream zone of diameter Dn and length Dn with Ln/Dn of from 0 to at most 25, to result in a draw ratio DR.sub.fluid=DR.sub.sp* DR.sub.ag of at least 150, wherein DR.sub.sp is the draw ratio in the spinholes and DR.sub.ag is the draw ratio in the air-gap, with DR.sub.sp being greater than 1 and DR.sub.ag at least 1. High-performance polyethylene multifilament yarn, and semi-finished or end-use products containing said yarn, especially to ropes and ballistic-resistant composites, are also disclosed.

A helmet shell is formed having an outer section of fibrous layers, a middle section of fibrous layers and an inner section of fibrous layers. The outer section layers contain high tenacity abrasive fibers in a resin matrix. The middle section layers contain high strength polyolefin fibers and are in the form of woven or knitted fabrics with a resin matrix. The inner section layers contain high strength polyolefin fibers and are in the form of non-woven fabrics with a resin matrix. The helmet is lightweight and resists penetration of rifle bullets.