The mechanisms of interfacial debonding of particle reinforcedrheological materials are studied. Based on an energy criterion, asimple formula of local critical stress for interfacial debonding isderived and expressed in terms of the interfacial energy. Theparticle size effect on interface debond- ing can then be analyzedeasily owing to the fact that critical stress is inverselyproportional to the square root of particle radius. By takingPP/CaCO_3 system as an example, the present energy criterion iscompared with the mechanical debonding criterion, and it is foundthat under the condition that bond strength is equal to matrixstrength and particle radius not over 0.2μm, the mechanicaldebonding cri- terion can be automatically satisfied if the energycirterion is satisfied.
