An article of footwear comprising relatively elastic and relatively inelastic materials chemically bonded together is disclosed. In one embodiment, the relatively elastic and relatively inelastic materials are arranged in such a fashion to impart flexibility to the article of footwear. In particular, plastic and rubber materials are bonded together to improve the flexibility of an outsole of an article of footwear. The invention also is directed to the fabrication of new or improved devices and elements for use in articles of footwear and their associated methods of construction such as closure mechanisms comprising relatively elastic straps bonded to relatively inelastic anchor portions and vice versa, articulating inelastic and elastic exoskeleton constructions useful in skates and ski boots, and elastic or inelastic eyelets surrounded by inelastic or elastic materials. The invention also is directed to chemically bonding relatively elastic to relatively inelastic materials for contemplated use in protective athletic equipment such as helmets and protective padding, and for use in prosthetic devices.