Deformation of rubber‐toughened polycarbonate: Macroscale analysis of the damage zone

Abstract

SYNOPSISTwo commercial core-shell rubbers were used as impact modifiers for polycarbonate (PC) .Specimens with a single semicircular edge notch were stretched uniaxially in order to study the prefracture damage evolution of blends under a triaxial tensile stress state. The irreversible deformation of modified PC included a cavitation mechanism in addition to the three shear modes of unmodified PC. A t the macroscopic level, the cavitation condition could be described by a mean stress concept. The corresponding critical volume strain for cavitation in PC blends was determined to be independent of rubber content but differed for the two impact modifiers. The critical volume strain for cavitation was used as an index of cavitation resistance for the impact modifiers. The effect of rubber content and temperature on Izod impact strength of the PC blends was also reported. From the relationship between the cavitation resistance and the Izod impact strength, it was proposed that impact modifiers with a higher cavitation resistance impart better toughness to blends with PC.

Shearing of particles during crack growth in polymer blends

“…1(a). Similar shapes were found near the fracture surface in nylon-rubber blends [16,17] and to somewhat lesser extent in PC blends [18]. Highly deformed cavitated particles that are also not aligned with the tensile direction, i.e., that are not perpendicular to the fracture surface, were observed in [14] too, but they do not tend to have the typical S shape.…”

Mechanical properties of poly(ethylene terephthalate) modified with functionalized polymers

“…The distance between the notch root and the onset of cavitation increases with the cavitation resistance of the elastomer, and in general, a larger distance is indicative of better toughness as long as the cavitation stress remains well below the crazing stress of the matrix. 10 The correlation between toughness and onset of cavitation was tested with the SEBS blends by measuring the length of the uncavitated shear yielding region on the fracture surface. This length decreased from 0.7 mm (SEBS2m) to 0.4 mm (SEBS1h) to 0.3 mm (SEBS2) to less than 0.05 mm (SEBS1), a trend that paralleled decreases in fracture stress and fracture energy.…”

Reactive acrylic liquid rubber with terminal and pendant carboxyl groups as a modifier for epoxy resin

“…The increase in functionality will increase the interfacial adhesion between the rubber particle and the epoxy matrix. Though the effect of other molecular and morphological parameters such as particle size, particle size distribution, and volume fraction of rubber on toughening have been extensively studied for rubber modified systems [23][24][25][26], the interfacial adhesion through the chemical bonding related studies are less [21,22]. In this paper, synthesis, characterization of liquid rubbers with the terminal and pendant groups, and evaluation of the rubber modified epoxy networks will be discussed.…”