Mechanical degradation of dilute solutions of high polymers in capillary tube flow

Abstract

SynopsisExperimental results on mechanical degradation in capillary tubes of polyisobutylene polymers in dilute solution are described. In laminar flow, degradation is independent of tube length, indicating that entrance effects are dominant. This shows that capillary experiments do not yield explicit information on the effect of shear stress on mechanical degradation. In turbulent flow, large entrance effects are also observed, but some degradation does take place in the fully developed flow region.

Water‐soluble polymers. LXXXII. Shear degradation effects on drag reduction behavior of dilute polymer solutions

“…17,[22][23][24][25][26][27][28][29] The rate of shear degradation is greatest for high molecular weight polymers at low concentration. [27][28][29] Shear degradation typically results in a rapid decrease in molecular weight that approaches a limiting polymer molecular weight (M tϱ ) after long degradation times.…”

Time dependence of turbulent drag reduction efficiency of polyisobutylene in kerosene

“…A larger value of h indicates fast degradation, while a larger value of W implies low shear stability. Recently, they suggested more terms for h, which is now a function of polymer concentration [10]; however we use rather Eq. (4) in this study.…”

“…Furthermore, Dschagarowa and Mennig [9] examined the concentration dependence and flow rate dependence in pipe flow of dilute PIB solutions. In the flow system, it was found that a majority of the polymer degradation occurred in the entrance region of a pipe [10,11] and the extent of the degradation increased with the addition of the passes [11]. And, the solvent effect on polymer hydrodynamic volume resulted in more violent degradation in a poor solvent than that in a good solvent [12,7].…”

Design Optimization of Scaffold Microstructures Using Wall Shear Stress Criterion Towards Regulated Flow-Induced Erosion

“…In other words, elemental density q e (1 or 0) in the BESO approach also represents the local polymer status in order to model the shear-induced polymeric erosion, i.e., 1 representing the noneroded status while 0 the eroded status. Following the erosion mechanism proposed by Culter et al [41], a WSS threshold [s ero ] is adopted to determine whether or not the chain scission would take place, i.e., q e ¼ 1; s e w < ½s ero 0; s e w ! ½s ero…”