A study on the fundamental ceramic–polymer interactions in the high CeO2-loading polyethylene glycol blend

Rheology of a polymer melt including ceramic particles is far cry from that of the pristine polymer phase because of the interactions between polymer and ceramic particles. This work focuses on the flow behavior of the blend comprising polyethylene glycol (PEG) melt and a fine powder (size <5 μm) of cerium(IV) oxide under low shear rates. The blend containing as high as 80 wt.% (or 41.6 vol.%) of CeO2 can still exhibit Bingham plastic response in the low shear rate range. Hence, the relative viscosities (ηrel) of the PEG–CeO2 mixtures with various volume fractions of CeO2 (ϕ) could be obtained at different temperatures, and these data were then used to simulate the rheological model developed in this work. This model was created by assuming that there are two primary forces governing the rheological behavior of the blend, which are the van der Waals attractive forces that exist among CeO2 particles and the chemical adsorption of PEG segments on CeO2 particles, respectively. The simulation turns out that this model matches more precisely the changes of ηrel versus ϕ at different temperatures than the three widely quoted models. Furthermore, the occurrence of the two stipulated forces in the PEG–CeO2 blend has also been verified by other experimental evidences, e.g. scanning electron microscopy (SEM), X-ray diffraction (XRD), FTIR, and differential scanning calorimetry (DSC).