2020/05/04 by Zipeng Xu, Ruikun Sun, Xu, Zipeng +7
Chemical Engineering · Physics and Astronomy · #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Rheology and Fluid Dynamics Studies #Soft Condensed Matter (cond-mat.soft) #Theoretical and Computational Physics
paper · pdf · doi:10.48550/arxiv.2005.01251
openalex publication_date 2020/05/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In addition to the terminal flow (the region I) and the shear thinning (the region II), we discover two new flow regions in capillary flow at the wall stress higher than the plateau modulus of the polymer. The region III violates the empirical Cox-Merz rule with a significantly weaker shear thinning than the region II, and the region IV exhibits unexpected shear thickening. Moreover, the crossover shear rates between the regions II and III and between the regions III and IV scale with the number of entanglement per chain, Z=Mw/Me, as Z^(-2.0) and Z^(-1.2) respectively. We attribute the weakening in shear thinning and the emergence of shear thickening to the deformation-induced non-Gaussian stretching of polymers. These observations offer the first experimental quantification of the deformation behaviors of polymer melts at high-stress shear.