  We study the influence of spherical, triangular, and rod-like nanoparticles
on the mechanical properties of a polymer nanocomposite (PNC), via
coarse-grained molecular dynamics simulations. We focus on how the nanoparticle
size, loading, mass, and shape influence the PNC's elastic modulus, stress at
failure and resistance against cavity formation and growth, under external
stress. We find that in the regime of strong polymer-nanoparticle interactions,
the formation of a polymer network via temporary polymer-nanoparticle
crosslinks has a predominant role on the PNC reinforcement. Spherical
nanoparticles, whose size is comparable to that of the polymer monomers, are
more effective at toughening the PNC than larger spherical particles. When
comparing particles of spherical, triangular, and rod-like geometries, the
rod-like nanoparticles emerge as the best PNC toughening agents.
