Critical Polymer Concentrations of Polyethylene Solutions in Pentane

Abstract

Critical polymer concentrations of polyethylene solutions in pentane were measured using a variablevolume view cell apparatus. The molecular weights of the polyethylene samples were 27 700 and 41 700 with polydispersity indexes M w /M n ) 2.00 and 3.70, respectively. The phase separation pressures (cloud point) of the polymer solutions were repeatedly measured in the polymer concentration range 0.3-11.0 mass %. Two types of phase separation patterns (dew-point and bubble-point types) were observed, depending on the polymer concentration. The critical polymer concentration was determined by locating a merging point of the two types of phase separation branches. The critical polymer concentrations for the two polyethylene solutions were 6.90 ( 0.1 (M w ) 27 700) and 3.95 ( 0.05 (M w ) 41 700) mass %, respectively.

Improved rheology and high‐temperature stability of hydrolyzed polyacrylamide using graphene oxide nanosheet

“…Polymer molecules can develop concentration‐dependent association, which can occur mostly when mixing with other substances like surfactants and nanoparticles . This association can be apparent at the concentration of the first break, often termed the critical association concentration (CAC), where polymer molecules and other substances begin to associate.…”

“…It is significant to know the CAC value to achieve required morphological features or specific modification of the polymer solution such as in a polymer/nanoparticle hybrid. However, the CAC value can be obtained using other approaches such as light scattering determination, variable view cell apparatus, and the changes in fluorescence characters when micellization occurs …”

Phase Behavior of Polymer Solutions from Macroscopic Properties: Application to the Perturbed Chain Statistical Associating Fluid Theory Equation of State

“…In Figure a modeling results for liquid−liquid equilibria of the system polyethylene ( M w = 41.7 kg/mol and M w / M n = 2.00) with n -pentane at three different temperatures are compared with the experimental data published by Yeo et al Calculations were made using polymer parameters determined in this work. Two comparisons were performed: in the first case, the results were obtained with k ij = 0, while in the second case the k ij parameter was adjusted to the experimental data at 423 K. The molecular weight distribution of this polymer was modeled using five pseudocomponents which were determined according to the algorithm suggested by Tork et al (see Table ).…”

Application of Polymer Based Nanocomposites for Water Shutoff—A Review

“…While higher viscosity is required to reduce water mobility and curb issues like fingering; very high polymer concentrations can lead to formation of aggregates that may block the pores and effectively reduce the permeability. The Critical Association Concentration (CAC) of the polymer plays a significant role in the rheology of the polymer hybrid as it is the concentration at which the polymer starts interacting with other substances such as surfactants and nanoparticles [33]. In Haruna et al's study [34], at 0.06 wt.% concentration of HPAM the gradient of the viscosity plot drastically changed with a sharp increase in viscosity observed when the polymer concentration exceeded this threshold value.…”