Admixtures either of a plastic and an elastomer, a plurality of thermoplastics, or a plurality of elastomers are formed into a shaped item for an article (such as a dynamic seal, a static seal, a gasket, a pump diaphragm, a hose, or an o-ring), and the thermoplastic is then cross-linked (cured). Radiation (preferably, electron beam radiation) is used for the cross-linking and for generating bi-modal molecules from the elastomer and the thermoplastic when both a thermoplastic and an elastomer are in the admixture.