3.4. Rheological behaviour
According to injection moulding requirements, a previous
rheological study of blends in the melting state was performed. The
viscosity of samples as a function of shear rate is presented in Fig. 5.
This shear rate range was selected because similar shear rate values
are reached during injection process. In all the samples, the viscosity
decreases as shear rate increases according to a pseudoplastic
behaviour which is the most suitable for the process. And on
the other hand, if wax content increases the viscosity of the blend
decreases.
Paraffin wax presents a Newtonian behaviour but its viscosity at
160 C is too much low to be measured through this method, that is
why this value was obtained by means of a logarithmic additivity
rule according to Eq. (1) [22]: