Flow behavior of polydimethylsiloxane

Viscosities of polydimethylsiloxane were measured over a wide range of shear rates and molecular weights to clarify the flow behavior of bulk polymers. It was observed that each flow curve for high molecular weight samples had an inflection point, and at high shear rates all curves tended to converge. The relationship between viscosities and molecular weights at various shear rates showed the following features: no sharp inflection in the zero shear relation and non‐Newtonian properties below Mc. It is suggested that viscosities of high molecular weight samples become almost the same, irrespective of molecular weight, at very high shear rates.