2016/12/29 by Pushpak Bhattacharjee, P. K. Bhattacharjee, Duc Nguyen +4 · 9 citations
Chemical Engineering · Chemistry · Materials Science · Medicine · #Blood properties and coagulation #Chemical physics #Chemistry #Composite material #Computational chemistry #Dynamics (music) #Extensional definition #Geology #Homogeneous #Materials science #Mechanics #Molecular dynamics #Physics #Polymer #Polymer crystallization and properties #Quantum entanglement #Quantum mechanics #Rheology and Fluid Dynamics Studies #Slip (aerodynamics) #Statistical physics #Strain (injury) #Strain rate #Thermodynamics
paper · doi:10.1021/acs.macromol.6b00823
published in Macromolecules 50(1), 386-395 (American Chemical Society)
openalex publication_date 2016/12/29 · openalex created_date 2017/01/06 · openalex updated_date 2026/07/28
The dynamics of chain entanglement/disentanglement in concentrated polymer solutions are matters of current debate. We report the results of step strain rate experiments in uniaxial extensional flow on a well-characterized polymer solution containing about 22 entanglements per chain which allows these dynamics to be probed. In these experiments the polymer solution is subjected to homogeneous stretching at a given strain rate up until a predetermined value of strain. After this strain is reached, the strain rate is changed to a new value, and stretching is continued until steady state is acquired in the extensional stress. The strain rates are increased in step-up experiments and decreased in step-down experiments. The strain rates are adjusted so that both the orientation and the stretching dynamics can be probed. Additionally, the predictions of two recent single-mode molecular models are evaluated against the experimental data. These models include the effects of entanglement dynamics in their predictions in an ad hoc manner. This leads to only a qualitative improvement in the predictive capacity of one of the models and reduces that of the other. Slip-link simulations using the primitive chain network model are also included for further insight into the underlying dynamics. The models are found to yield qualitative predictions of the experimental observations.