Oils and biodiesel viscosities were evaluated using a rotational
viscometer Haake model VT500 and a NV sensor (Fisher Scientific,
Aalst, Belgium). The samples were kept at 40 °C using a water bath
and 10 ml of each sample was introduced between the two coaxial
cylinders, maintaining the specified temperature. Shear stress (τ) was
measured using different shear rates (γ), from 0 to 3000 s−1
. Then,
the dynamic viscosity (μ, Pa.s) was determined by the slope of the line
obtained when plotting shear stress (τ, Pa) versus shear rate (γ, s−1
)
for all the samples. The density of all the samples was measured at
40 °C. Using an electronic pipette, 5 ml of each sample were taken and
then weighted to determine its mass. The dynamic viscosity and density
were used to determine the kinematic viscosity at 40 °C, expressed
in mm2
/s.