Interfacial interactions and the properties of filled polymers: I. Dynamic‐mechanical responses

The dynamic mechanical responses of rutile‐filled, chlorinated polyethylene (CPE) were studied as a function of temperature, of filler loading, and of filler surface condition. An objective was to establish the influence of matrix‐filler interactions on mechanical properties. Necessary information on potential interactions between matrix and filler was obtained from inverse gas chromatographic data, in the form of an acid‐base interaction parameter, Ω. The damping peak in filled CPE compounds was depressed by the pigment, as called for by theoretical models. The magnitude of the effect exceeded expectations, however, and clearly depended on the strength of interfacial interactions. These were consistent with the acid‐base ranking of CPE and the various rutiles, as given by Ω. It has been postulated that in the presence of acid‐base interactions, an immobilized layer of polymer in the vicinity of solid particles increases the effective particle dimension, thereby accounting for the observed variations in relative damping. Additional effects of matrix‐filler interaction were noted in the variation of storage moduli with loading and temperature. Again, the effects tend to be more pronounced when significant specific interactions between matrix and solid are operative. These observations point to the inadequacy of existing models as interpretative bases for dynamic mechanical properties in systems with significant specifie interactions among their components.