scholarly journals Effects of polymer concentration and chain length on aggregation in physically associating polymer solutions

2011 ◽  
Vol 14 (4) ◽  
pp. 43601 ◽  
Author(s):  
Han ◽  
Zhang ◽  
Ma ◽  
Zhang ◽  
Guan
Keyword(s):  
Chain Length ◽  
Polymer Solutions ◽  
Polymer Concentration ◽  
Associating Polymer

Termination in Semi-Dilute and Concentrated Polymer Solutions

2009 ◽  
Vol 62 (8) ◽  
pp. 857 ◽  
Author(s):  
Geoffrey Johnston-Hall ◽  
Michael J. Monteiro
Keyword(s):  
Chain Length ◽  
Power Law ◽  
Polymer Solutions ◽  
Polymer Concentration ◽  
Star Polymer ◽  
Polymer Systems ◽  
Theoretical Predictions ◽  
The Matrix ◽  
Concentrated Solution ◽  
Blob Model

The aim of the present work was to develop a deeper understanding into termination processes in the semi-dilute and concentrated regimes. The study was carried out to examine the effect of termination between linear polystyrene radical chains in linear, four-arm star, and six-arm star polymer systems using the reversible addition–fragmentation chain transfer chain length-dependent termination method. In particular, the power-law dependencies of both chain length and polymer concentration were evaluated in the semi-dilute and concentrated regimes. We found that theoretical predictions based on the blob model were in good agreement with the experimentally observed evolution of the rate coefficient for biomolecular termination, kti,i(x), in the semi-dilute solution regime. In addition, solvent quality was found to decrease with increasing chain length, increasing polymer concentration and as a function of the matrix topology (i.e. for star polymer solutions). In the concentrated solution regime, the role of chain entanglements became evident by determining the conversion-dependent power-law exponent, βgel (where kt ≈ x–βgel), which increased in the order: linear < four-arm star < six-arm star polymer systems. Above the critical chain length ic, termination was found to be primarily conversion-dependent, implying entanglements dominated termination between linear polymeric radicals. Although this may suggest that reptation plays an important role, our data are in disagreement with this theory, suggesting that the polymer matrix cannot be regarded as static or immobile on the diffusion time scales for bimolecular termination.

Heat capacities and volumes in aqueous polymer and polymer–surfactant solutions

1987 ◽  
Vol 65 (5) ◽  
pp. 990-995 ◽  
Author(s):  
Gérald Perron ◽  
Josée Francoeur ◽  
Jacques E. Desnoyers ◽  
Jan C. T. Kwak
Keyword(s):  
Thermodynamic Properties ◽  
Chain Length ◽  
Polymer Concentration ◽  
Heat Capacities ◽  
Aqueous Mixtures ◽  
Alkyltrimethylammonium Bromides ◽  
Aqueous Polymer ◽  
Surfactant Interactions ◽  
Polymer Surfactant ◽  
Polymer Interaction

The apparent molar volumes and heat capacities of aqueous mixtures of neutral polymers and ionic surfactants were measured at 25 °C. The polymers chosen were poly(vinylpyrrolidone) (PVP) and poly(ethyleneoxide) (PEO) and the surfactants were the C8, C10, and C12 homologs of sodium alkylsulfates and the C10, C12, and C16 homologs of alkyltrimethylammonium bromides. The polymer–surfactant interactions depend on the nature of both components and on the chain length of the surfactant. The thermodynamic properties of the cationic surfactants are essentially the same in the absence and presence of polymer indicating little surfactant–polymer interaction. On the other hand, the thermodynamic properties of anionic surfactants are shifted, upon the addition of polymers, in the direction of enhanced hydrophobic association. The effect increases with the surfactant chain length and with the polymer concentration. The effect is larger with PVP than with PEO.

scholarly journals Direct-Write Drawing of Carbon Nanotube/Polymer Composite Microfibers

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Scott M. Berry ◽  
Santosh Pabba ◽  
Robert W. Cohn ◽  
Robert S. Keynton
Keyword(s):  
Carbon Nanotube ◽  
Polymer Solutions ◽  
Fiber Diameter ◽  
Axial Strain ◽  
Polymer Concentration ◽  
Strain Rates ◽  
Direct Write ◽  
Composite Fibers ◽  
Capillary Thinning ◽  
Doped Polymer

Carbon-nanotube- (CNT-) doped polymer solutions were drawn into arrays of microfibers using a novel direct-write process. This process utilizes a micromanipulator-controlled syringe loaded with solvated polymer mixed with CNTs to “write” networks of composite fibers with precisely positioned endpoints. The diameters of these composite fibers are correlated to the degree of capillary thinning that occurs prior to the solidification of the directly written CNT-doped solution filament. The fibers had diameters ranging from 7 μm to over 100 μm and possessed conductivities as high as 0.1 Sm−1. Fiber diameter was found to increase with increasing polymer concentration and decreasing fiber length and can be controlled through modulation of these parameters. The presence of CNTs was found not to significantly affect fiber diameter, despite the CNTs significant effect on viscosity, which was previously reported to influence diameter. This discrepancy is likely related to the non-Newtonian effects of CNT/polymer solutions, including an apparent shear thinning at increasing axial strain rates.

Velocity fluctuations of fracturelike disruptions of associating polymer solutions

1995 ◽  
Vol 51 (2) ◽  
pp. 1338-1343 ◽  
Author(s):  
Jordi Ignés-Mullol ◽  
H. Zhao ◽  
J. V. Maher
Keyword(s):  
Polymer Solutions ◽  
Velocity Fluctuations ◽  
Associating Polymer

scholarly journals Evaporation-induced Rayleigh–Taylor instabilities in polymer solutions

2020 ◽  
Vol 378 (2174) ◽  
pp. 20190533 ◽  
Author(s):  
E. J. Mossige ◽  
V. Chandran Suja ◽  
M. Islamov ◽  
S. F. Wheeler ◽  
Gerald. G. Fuller
Keyword(s):  
Molecular Weight ◽  
Time Scales ◽  
Polymer Solutions ◽  
Critical Concentration ◽  
Polymer Concentration ◽  
Onset Time ◽  
Dense Layer ◽  
Strong Concentration ◽  
Aqueous Polymer ◽  
Gravitational Instabilities

Understanding the mechanics of detrimental convective instabilities in drying polymer solutions is crucial in many applications such as the production of film coatings. It is well known that solvent evaporation in polymer solutions can lead to Rayleigh-Bénard or Marangoni-type instabilities. Here, we reveal another mechanism, namely that evaporation can cause the interface to display Rayleigh–Taylor instabilities due to the build-up of a dense layer at the air–liquid interface. We study experimentally the onset time ( t p ) of the instability as a function of the macroscopic properties of aqueous polymer solutions, which we tune by varying the polymer concentration ( c 0 ), molecular weight and polymer type. In dilute solutions, t p shows two limiting behaviours depending on the polymer diffusivity. For high diffusivity polymers (low molecular weight), the pluming time scales as c 0 − 2 / 3 . This result agrees with previous studies on gravitational instabilities in miscible systems where diffusion stabilizes the system. On the other hand, in low diffusivity polymers the pluming time scales as c 0 − 1 . The stabilizing effect of an effective interfacial tension, similar to those in immiscible systems, explains this strong concentration dependence. Above a critical concentration, c ^ , viscosity delays the growth of the instability, allowing time for diffusion to act as the dominant stabilizing mechanism. This results in t p scaling as ( ν / c 0 ) 2/3 . This article is part of the theme issue ‘Stokes at 200 (Part 1)’.

Chain length dependence of liquid—liquid equilibria of binary polymer solutions

Polymer ◽  
1998 ◽  
Vol 39 (8-9) ◽  
pp. 1735-1739 ◽  
Author(s):  
Bong Ho Chang ◽  
Kyong-Ok Ryu ◽  
Young Chan Bae
Keyword(s):  
Chain Length ◽  
Polymer Solutions ◽  
Length Dependence ◽  
Binary Polymer

Synthesis of Ionic Hydrophobic Associating Polymer and it’s Aqueous Solution‘s Viscosity Characteristics

2014 ◽  
Vol 628 ◽  
pp. 120-124
Author(s):  
Fa Yong Feng ◽  
Pei Zhi Yu
Keyword(s):  
Polymer Concentration ◽  
Synthesis Method ◽  
Water Soluble ◽  
Soluble Polymer ◽  
Water Soluble Polymer ◽  
Viscosity Behavior ◽  
Hydrophobically Associating ◽  
Temperature Shear ◽  
Hydrolyzed Polyacrylamide ◽  
Associating Polymer

Brief introduction of research progresses of hydrophobically associating water soluble polymer, as well as a synthesis method of a hydrophobically associating water-soluble polymer P (AM/KAA/MAHB). Meanwhile the molecular structure is characterized, and the viscosity behavior of the ionic hydrophobic-associating polymer solution is analyzed. The influences of polymer concentration, temperature, shear rate and water salinity of the saline solution on apparent viscosity are discussed. The critical associating concentration of polymer in salt solutions and salt thickening effect are also studied. The results show that the polymer possesses obvious temperature resistance and salt tolerance compared with partially hydrolyzed polyacrylamide polymer.

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