Method for manufacturing a closure for a product-retaining container

A method for manufacturing a closure constructed for being inserted and securely retained in a portal-forming neck of a product-retaining container is provided. Such method may include intimately combining a plurality of particles comprising cork and having a specified particle size distribution with a plastic material including one or more thermoplastic polymers， optionally in combination with other constituent(s) to form a composition， heating the composition to form a melt， extruding or molding a closure precursor from the melt to provide a specified water content range， and optionally cutting and/or finishing the closure precursor. A composition for use in manufacturing a closure for a product-retaining container includes a plurality of particles comprising cork and having a specified particle size distribution with a plastic material including at least one thermoplastic polymer， optionally with other constituent(s). A closure produced from the composition and use of a closure are also provided.