Mechanical properties and fracture surface morphologies in unnotched specimens of rubber-PMMA composites

Correlations between mechanical properties and microscopic features were investigated using unnotched specimens of rubber-PMMA composites in very low to medium range of cross head speeds. It is found that: (1) a trapezoid-shaped smooth region and fish scale-like texture with bands in rough region correlates with brittle failure in pure PMMA, while a quarter circle-shaped smooth region and hackle-like texture, and the presence of dimples and/or voids correlate with ductile failure in rubber-PMMA composites; (2) decrease in degree of roughness in rubber-PMMA composites can be correlated with decrease in Young's modulus; (3) decrease in size of the smooth region with increasing speed can be correlated with decrease in modulus of toughness; (4) larger smooth region in rubber-PMMA composites containing more rubber correlates with higher modulus of toughness