Although the coupling effects between the flow birefringence
and thermal birefringence are neglected in calculations of the total birefringence, the present study shows that the thermal birefringence contribution is significant.
Laboratory workshops will include: Shear flow experiments (viscosity and normal force measurements in cone-and-plate and parallel plate flow, viscosity measurements in concentric cylinder flow, high shear rate viscometry in capillary viscometers and relaxation modulus in step strain stress relaxation); Elongational flow experiments; Linear viscoelastic tests; and Laser doppler velocimetry and flow birefringence
First the extinction angle was measured and, with the help of a compensator the optical path difference--OPD was determined and then the flow birefringence
In the present study, extensive simulations of the various components of the flow birefringence
developed during the filling, compression, packing, and cooling stages of the ICM of a center gated disk of polystyrene (PS) and polycarbonate (PC) is carried out by using hybrid CV/FE/ FD method.
30), (38) also reported a negative contribution of clay particles to the overall flow birefringence
of viscoelastic clay solutions.
The flow birefringence
of aqueous suspension which is formed as aresult of the alignment of cellulose nano crystals in the direction of flow is viewed under cross polarized light and is shown in Fig.
The residual flow birefringence
in the amorphous region can be calculated by the stress-optical rule during the nonisothermal flow and the subsequent relaxation.
Janeschitz-Kriegel, Polymer Melt Rheology and Flow Birefringence
, Springer, New York (1983).
Researchers have applied the stress-optical rule in numerical simulations of flow birefringence
(4-9), wherein most of the studies have considered polystyrene (PS) with a high molecular weight.
The flow birefringence
technique is very useful for investigating the stresses occurring in film flow.
The latter quantity can be measured in a wide range of shear rates in different ways, if necessary with the aid of flow birefringence
in duct flow.
The flow-induced birefringence has one peak at the end of filling stage while it has two peaks at the end of packing stage, and remains unchanged afterwards since the temperature over the entire thickness is low enough so that flow birefringence
has been frozen.