Contrasting rubber-toughen mechanisms for glassy polymers

We perform standard pre-yield and post-yield stress relaxation to probe molecular mobility in various rubber-toughened polymer glasses and to differentiate between “apparent” and true yielding. The rubber-toughened PS and SAN, e.g., HIPS and ABS, show apparent yield at high strains whereas a new generation of PMMA based nanocomposites from Dow Chemical is transparent, truly ductile and shows enhanced molecular mobility in post-yield deformation at different draw rates, form a sharp contrast with the conventional materials such as HIPS and ABS.