Abstract: The invention relates to articles consisting of highly oriented polyolefins having an ultrahigh molecular weight of more than 600,000 g/mol (weight-average molecular weight), especially filaments, fibers, yarns, fabrics and films, having good wetting and adhesive properties, especially on conventional matrix materials, which have been subjected to a plasma treatment of their surface, and also to a process for producing these articles and to their use for the manufacture of composites with the use of conventional matrix materials. In these composites, yarns according to the invention, for example, show a substantially higher adhesive strength than corresponding yarns which have not been plasma-treated, their tensile strength not being impaired by the plasma treatment.

Abstract: Polethylene articles having a high tensile strength above 2.0 GPa, a modulus above 70 GPa and a creep below 3.times.10.sup.-7 sec.sup.-1 are obtained via thermoreversible gelation of a solution of polyethylene with a Mv above 5.times.10.sup.5 kg/kmole, followed by ultradrawing. As polyethylene a copolymer or a blend is used containing 2-20 lower alkyl side chains per 1000 carbon atoms.

Abstract: The adhesion of highly oriented polyolefin objects, in particular polyethylene filaments, to e.g. polar, polymer matrices is improved by contacting the surface of the object with a solvent for 0.5-2 minutes at a temperature above the dissolution temperature of the polyolefin.

Abstract: An apparatus for the surface treatment of synthetic fibers or yarns, in particular of fibers and yarns of polyethylene of ultra-high molecular weight, for improvement of the adhesion, a corona is generated by means of two active electrodes (10, 12), between which the fibers or yarns are passed parallel to the longitudinal extent. The electrodes are designed with a surrounding insulating sheath. The current fed to the electrode (16) is phase-shifted by .phi.=180.degree. with respect to the current fed to the electrode (10).