Transient Shear Flow of Thermotropic Main-Chain LCPs

2 Transient Shear Flow of Thermotropic Main-Chain LCPs 

Transient shear flow often provides us with very valuable information on the unique rheological characteristics of polymeric liquids, particularly multiphase polymeric liquids including LCPs. A better understanding of the transient shear flow behavior 

1 Growth of Shear Stress and First Normal Stress Difference During Transient Shear Startup of Thermotropic Main-Chain LCPs 

Owing to the strong dependence of the rheological behavior of TLCP on thermal and deformation histories, the transient shear flow data for 73/27 HBA7HNA copolyester reported by two laboratories have been found to be quite different (Cocchini et al. 1991 Guskey and Winter 1991). As we have already pointed out, it is extremely important for one to control the initial morphology (i.e., initial conditions) of test specimens in order to obtain reproducible transient shear flow data for TLCPs. 

As we have demonstrated, an erroneous conclusion can be drawn on the sign of first normal stress difference in TLCP if the transient or steady-state shear flow experiments were carried out in the presence of residual normal force that was generated 

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