Fractography of injection molded polycarbonate acrylonitrile‐butadiene‐styrene terpolymer blends

Abstract

Fractography has been used in the post-failure analysis of single edge notched specimens of injection molded blends of polycarbonate (PC) and acrylonitrilebutadiene-styrene terpolymer (ABS). The mode of ductile tensile fracture of single edge notched specimens depended on composition. Plane stress shear tearing was observed in the composition range PC/ABS 90, ' 10 to 70/30 by weight where PC was the continuous phase. Intermediate compositions, PC/ABS 60/40 to 40/60, had a co-continuous or almost co-continuous phase morphology; these blends fractured by mixed mode pop-in, where a tunneling center crack relieved the triaxiality and permitted plane stress shear lips to form near the edges. Hemngbone fracture, a plane strain mode characterized by discontinuous crack growth, was observed when Al3S was the continuous phase, PC/Al3S 30/70 to 10/90. An S-shaped relationship was observed between the ductile-to-brittle transition temperature and the composition. Addition of AI3S to PC increased ductility up to PC/AI3S 70/30 and 60/40, which were the most ductile compositions. Further addition of Al3S decreased the ductility, and the least ductile compositions were PC/AT3S 30/70 and 10/90.

Effects of microstructure on crack tip fields and fracture toughness in PC/ABS polymer blends

“…The latter was mainly determined by the rubber content, and the maximum toughness was observed at around 15% rubber in the ABS. Similar highly non-monotonous variations of the fracture properties with composition are reported by other researchers (e.g., Lee et al 1992;Balakrishnan and Neelakantan 1998;Inberg 2001). In accordance with the above mentioned behavior of PC/ ABS under unnotched conditions, an enhanced fracture toughness compared to that of neat PC is only observed for sufficiently sharp notches.…”

“…In contrast, the presence of ABS which is able to undergo volumetric expansion upon cavitation of the rubber particles causes a relief of hydrostatic stress (thereby suppressing crazing) and enables shear yielding in the PC. The qualitative picture of this toughening mechanism in PC/ABS, which is confirmed by microplastic deformations visible on the fracture surface, is generally agreed upon (e.g., Ishikawa and Chiba 1990;Lee et al 1992;Seidler and Grellmann 1993;Greco et al 1994;Ishikawa 1995;Inberg 2001). However, the efficiency of toughening strongly depends on various parameters, the rubber content in the ABS probably being the most important one.…”

“…The superior fracture toughness of PC/ABS blends compared to neat PC in the presence of sharp notches or pre-cracks is commonly ascribed to the occurrence of massive plastic deformation enabled by the ABS and to the suppression of crazing in the PC (e.g., Lee et al 1992;Greco et al 1994;Inberg 2001). The latter is a consequence of a relief of hydrostatic stress caused by the dilation of the ABS.…”

Processing and properties of engineering plastics recycled from waste electrical and electronic equipment (WEEE)

“…On the other hand, Lee et al [11] studied extensively the morphology of PC/ABS blend throughout the entire composition range. The PC-rich blends showed that dispersed ABS obtained a bead-and-string structure.…”

Structured latex particles based on natural rubber for high-impact polymer blends

“…In the present paper, their effect on polymer blends, made of polycarbonate (of bisphenol A, PC) and PMMA (plus NR-M) or PS (plus NR-SM), is discussed. These blends are related to commercial PC/ ABS blends [7][8][9][10] . Two morphologies are conceivable: the latex particles are either dispersed in one of the homopolymer phases, or they are concentrated between the phases 11) .…”