The unsteady-state contact angle on the interface between the polymer melt and TiO2 was determined. The drop in the contact angle with time can be modeled as an exponential decay in terms of two critical indices, the retardation time tau and the contact angle in equilibrium state A(infinity) Molten polystyrene (PS) has the smallest equilibrium angle A(infinity) followed by polytrimethylene terephthalate (PTT) and polymethyl methacrylate (PMMA), which has the greatest angle. Experimental results also indicate that a drop in the viscosity of the melt reduces A(infinity) and increases tau HIPS, modifying PS with polybutadiene particles yields a high contact angle A(infinity) and a low tau value. A plastogram for PS and HIPS with the same TiO2 loading (25 wt%) shows a marked torque deviation between PS and HIPS (7.1 Nm vs. 8.5 Nm), suggesting that a higher A(infinity) corresponds to a higher torque in the polymer compounding process.