Abstract
Polymer nanocomposites, especially nanoclay composites, have received much attention in recent years. While it is the functional properties of these composites that are the driving force, good mechanical properties are necessary in most applications. Although claims are made that the mechanical properties of nanocomposites should be excellent, in practice the mechanical properties are often disappointing. Soft or hard spherical particles can toughen semicrystalline polymers, but plate-like nanoclay particles have not produced any significant toughening action and frequently cause significant embrittlement. In this paper the toughening of semicrystalline polymers with nanoparticles, and particularly the difference in behaviour of spherical and plate-like particles is reviewed.