The capillary flow of silicones

摘要

AbstractThe non‐Newtonian flow of silicone fluids in capillaries was investigated with special emphasis on the viscoelastic nature of entrance and exit effects. At low pressures the power law was obeyed, while at high pressures considerable deviations were observed, particularly with short capillaries. For capillaries with large length‐to‐radius ratios, the flow index and consistency approached the Newtonian values. Entrance effects were successfully analyzed by the method proposed by Bagley. At low shear stresses the end correction was dependent only on the geometry of the apparatus. An elastic contribution to the end correction was observed only at high shear stress, indicating a relatively mild viscoelastic behavior. Additional evidence indicating small elastic effects was obtained from swelling measurements of capillary