The Mullins Softening Effect

Mullins softening may be defined as the reduction of modulus caused by successive stretching (Bachmann et al, 1959 Boonstra, 1965 Bueche, F., 1965 Dannenberg, 1966 Harwood et al, 1967 Mullins, 1969 Mullins and Tobin, 1956 Sellers and Toonder, 1965). This phenomenon is characteristic of truly reinforcing fillers, but occurs to a lesser extent in gums and non-reinforced systems (Kraus, 1971). 

Explanations of the Mullins effect have included failure of weak linkages, failure of network chains extending between adjacent filler particles, and polymer-filler bond failure, a form of dewetting. Brennan et al. (1969) and 

---