Abstract
Rheological properties of rigid vinyl sheets prepared according to several general formulae were examined within the range of manufacturing temperature. In consequence, it was revealed that the representative equation for non-Newtonian fluid
D=1/η*τnw
was applied for rigid vinyl sheets, where
η*: coefficient of viscosity
τw: shearing stress along the wall
n: non-Newtonian constant.
As to the rigid vinyl sheets, it was shown that the value of n is greater than 2 even at the temperature higher than 160°C.
Applying Poiseville′s equation, apparent viscosity η* corresponding to various τw was calculated, then η0 was obtained by extrapolating η* to τw=0. The relation between log η0 and 1/T was shown by linear diagram, where T was absolute temperature. From this relation, free energy change associated with the activation of flow was calculated.
The above mentioned results mean that higher temperature and higher pressure should be necessary for manufacturing of rigid vinyl sheets as compared with other plastics.
