US T960004 I4
a polymer melt's rheological properties are comprehensively described by defining the constants K and n in the rheological equation: T= KGn where T= shear stress and G= shear rate. The constants are determined by a rheometer which divides a molten polymer sample into two streams pumped by positive displacement pumps having identical speed-displacement characteristics past pressure transducers and finally through dissimilar capillaries to atmosphere. The pressure in each line is regulated at a predetermined level. Pressure and tachometer readings are used to compute the constants K and n.