Fine structures and fracture processes in plastic‐rubber two‐phase polymer systems III. Temperature dependence of Charpy impact strength

Notched Charpy impact strengths of a series of plasticrubber two‐phase polymer systems were measured over a wide range of temperatures. Blends of polyvinylchloride and rubbers with varying chemical structures, and several ABS polymers were investigated. In all systems, Charpy impact strength began to increase near the T g of the rubber component followed by a logarithmic increase with increasing temperature. The trend is expressed by the following empirical relation: where I is Charpy impact strength, A and B are constants, and T is the absolute temperature. This equation is applicable between the T g 's of the plastic and the rubber components. The increasing tendency of impact strength, i.e. the B value of the above equation, is depressed mainly by the decrease of the compatibility and/or the interfacial adhesive force between the two phases. Toughening mechanism and the ways of increasing toughness are discussed based on the craze formation mechanism.