Torque Rheometer

nvm, got it

It depend of what you want to do with it. Are you intending to mix polymers, to add solid charges in polymers? Are you using it as a rheometer, to measure the flowing properties of your material, or as a mixer?

If you want to do precise measurement of the torque vs RPM (and temperature) you need that the heating of the 3 zone work properly because you may have thermal gradient in your sample.

But if you are using the instrument only for mixing (or if you don't need very accurate measurements) it could probably do the job with only the middle zone heating. The viscous heating of your material will help to uniformize the temperature as well as the forced convection of the mixing.