flow birefringence


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flow birefringence

[¦flō ‚bī·rə′frin·jəns]
(physical chemistry)
Orientation of long, thin asymmetric molecules in the direction of flow of a solution forced to flow through a capillary tube.
References in periodicals archive ?
They found that increase in temperature and compression stroke can significantly reduce the birefringence, and the flow birefringence of the parts processed with switchover time is higher compared to those of without switchover time.
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.
To calculate the flow birefringence, a linear stress-optical rule [32] is used.
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 calculated.
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.
Wales, The Application of Flow Birefringence to Rheological Studies of Polymer Melts, DeIf University Press, Netherlands (1976).
(30), (38) also reported a negative contribution of clay particles to the overall flow birefringence of viscoelastic clay solutions.
Wales, The Application of Flow Birefringence to Rheological Studies of Polymer Melts, Delf University Press, Netherlands (1976).
The residual flow birefringence in the amorphous region can be calculated by the stress-optical rule during the nonisothermal flow and the subsequent relaxation.
Wales, The Application of Flow Birefringence to Rheological Studies of Polymers, Delft University, Rotterdam (1976).
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.