Loading rate dependence of the deformation and fracture mechanisms in impact modified poly(methyl methacrylate)

The tensile and fracture properties of rubber toughened poly(methylmethacrylate) (rtPMMA) modified by spherical core-shell particles, and poly(urethane)/poly(methyl methacrylate) (PU/PMMA) interpenetrating polymer networks (IPN) are investigated at different strain rates. The deformation and fracture mechanisms are studied by transmission electron microscopy (TEM). The results of the tensile tests show that deformation in both rtPMMA and IPN involves cavitation. The amount of cavitation increases with the strain rate in both kinds of material. This leads to similar mechanical properties in each case, and shows that a spherical particle morphology is not prerequisite for cavitation. A phenomenological model of the micromechanisms of deformation in core-shell particle modified PMMA is proposed.