The Essential Handbook of Polymer Terms and Attributes

76 Impact Modifier

DOI: 10.1201/9781003161318-76

Impact modifiers are additives to increase the durability and toughness of molded or extruded plastics, particularly those subject to impact forces or cold weather service.

Impact modifiers, which are applied as rubber particles in micron size, can absorb or dissipate the energy of impact. In 1956, Merz, and later in 1980 Kunz and coworkers, suggested that the function of the rubber particles was to bridge the cracks and so prevent the crack growing to a catastrophic size (Figure 76.1). The increase in toughness of the multiphase polymer can be considered as the amount of elastic energy stored in the rubber particles during stretching, which dissipates irreversibly when the particles rupture. ...