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.