Assessment of the Doi-Ohta theory for co-continuous blends under oscillatory flow

Predictions of the semi phenomenological Doi-Ohta theory for the rheology a nd morphology of immiscible blends are compared to experimental data of a 4 0/60 blend of PMMA/P alpha MSAN with a co-continuous structure. Since the D oi-Ohta theory actually was developed for co-continuous blends, published c omparisons on droplet-matrix blends are not considered as adequate. It is v erified how the polymeric constituents contribute to the blend response and it is shown how the phenomenological parameters of the Doi-Ohta theory can be determined. Subsequently, these parameters are used to predict the morp hology evolution and theological response of the blend under oscillatory fl ow. The evolution of the storage modulus clearly reflects the changes in mo rphology of the blend over time and strain amplitude in agreement with the theoretical predictions. Below a critical strain amplitude the co-continuou s structure will coarsen until a droplet-matrix morphology is generated but large strain amplitudes are effective enough to stop domain growth. (C) 20 01 The Society of Rheology.