phenomenon, higher temperature shortens the relaxation process
of a visco-elastic polymer. Caused by a lower viscosity and
associated better mobility of the molecules, the polymer molecules
return faster to their energetically stable state. Further, the specific
mechanical energy (SME) has an influence on this die-swelling
phenomenon as well. SME is the amount of mechanical energy to
be imparted into the blend at a set temperature in order to transfer
it to the rubbery state. It equals to the amount of mechanical
energy dissipated as heat inside the material (Eq. (9)) (Godavarti
and Karwe, 1997). Influences on the SME are the configuration of
the screws (see Fig. 2), the engine power, the rotational speed of
the screws, and the product output.