In this report, the authors tried to represent the characteristics of extruder by the transfer function obtained from the pulse testing method and to discuss the mixing efficiency under different dimension of screw and dies.
A colored chip was applied as the impulse signal into the extruder and those distributions of color density were measured as the function on of the length of flow.
Those distribution patterns are represented by:
1/K (exp(-1/T_l) + exp(-1/T₂) )
Coefficient K and factor T vary with the rate of screw revolutions, screw compression ratio and die dimensions (L/D), and the transfer functions of extruder are represented as the second or third order characteristic function by analysing those distribution patterns of Fig. 8 -Fig. 10 numerically.
The good coincide was found between the characterization of extruder based on back mixing model and the experimental results obtained by the pulse testing method.