A process including: introducing and continuously melt mixing in an extruder a mixture of a first resin feed and a second resin feed; measuring within the extruder the melt rheology of the resulting melt mixture of the first and second resins; determining the relative ratio of the first resin and a second resin from the melt rheology in the resulting melt mixture; and adjusting the relative feed ratio of the first resin and second resin feeds introduced to the extruder.