ABSTRACT
Filled rubber material exhibit a typical reduction of the stress response at strains smaller than the maximum strain reached in the loading history. This is known as the Mullins effect (Mullins 1948). Several molecular processes have been proposed to be responsible for the Mullins effect. Mullins himself distinguished a hard and a soft rubber fraction, with hard rubber being converted into soft rubber by prestraining. Bueche (1960) attributed softening to the debonding of chains from fillers. Based on this assumption, Govindjee & Simo (1991) proposed a decomposition of the rubber network into a purely elastic polymer part (CC) and a polymer-filler network (PP) which provides the softening. According to Klüppel (2003), the breakdown of filler aggregates is responsible for the Mullins effect. Marckmann et al. (2002) considered a network alteration due to the breakdown of crosslinks and weak bonds as reason for the softening. Various other concepts have been suggested, for instance slipping of chain molecules or molecule disentanglement. For an overview refer to Diani, Fayolle, & Gilormini (2009).
