PREDICTION OF THE CRITICAL PARTICLE-SIZE FOR TOUGHENING A GLASSY POLYMER

A bilayer specimen composed of a thin polystyrene (PS) film on a polyc arbonate (PC) mini-bar was prepared for tensile test. It was observed by scanning electron microscopy that periodic cracks appeared in the P S film when the specimen was deformed in tension. From the maximum cra ck spacing in the PS, the ultimate shear stress at the PS/PC interface was estimated to be 49 MPa using the periodic cracking method. Based on the deformation mechanism operative in the glassy polymer and the m easured crack spacing in the PS film, a new methodology was proposed a nd applied to predict the critical particle size for toughening a PS/P C polymer blend. (C) 1997 Elsevier Science Ltd.