Development of a predictive power law relationship for polymer composites based on newtonial carrier concentrated slurries

A new theory that predicts the power law “ n ” for Newtonian carrier particulate composites has been developed using percolation theory concepts. Many polymer composites, such as sheet molding compound, polyurethanes based on polymer‐polyols, and highly filled epoxy compounds, are generated using highly filled Newtonian carriers. Essentially, all of slurries that have a high concentration of filler become shear thinning at some shear rate. Several sizes of calcium carbonate were initially investigated because of their extensive use in many industries as fillers. A new function was found that linearly correlates the power law constant, n , to the concentration of the filler above the percolation concentration. The behavior of this function suggests that the Newtonian to power law behavior may be dominated by percolation processes. A new percolation theory based model was developed that theoretically predicted the power law from the volume of the nondissipating clusters. A theory is proposed that relates the plug volume in tube flow to the power law, n . The central plug in tube flow was experimentally shown to be a nondissipating volume in the flowing slurry. Data were taken in Poiseuille flow that correlates the power law, n , calculated in the classical manner using pressure drop along the tube with the power law, n , calculated from the percolation‐based theory. POLYM. COMPOS., 39:1172–1191, 2018. © 2016 Society of Plastics Engineers