Rheologica Acta

, Volume 45, Issue 6, pp 813–824

Linear viscoelastic master curves of neat and laponite-filled poly(ethylene oxide)–water solutions

Original contribution

DOI: 10.1007/s00397-005-0059-x

Cite this article as:
Daga, V.K. & Wagner, N.J. Rheol Acta (2006) 45: 813. doi:10.1007/s00397-005-0059-x
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Abstract

Aqueous solutions composed of dispersed nanoparticles and entangled polymers are shown to exhibit common viscoelasticity over a range of particle and polymer concentrations. Time–temperature superposition and time–concentration superposition are applied to generate rheological master curves for neat and laponite-filled aqueous solutions of poly(ethylene oxide). The shift factors were correlated in terms of temperature and concentration and are found to differ from previous reports for ideal polymer solutions, which can be rationalized with a molecular interpretation of the structure of the laponite–polymer solutions. Laponite addition to the concentrated polymer solution is observed to increase the relaxation time but decrease the elastic modulus, which is a consequence of polymer adsorption and bridging. The addition of small amounts of laponite to stable PEO–water solutions also leads to ageing on the time scale of days.

Keywords

Nanocomposite Polymer solution Laponite Nanoparticle Time–temperature superposition Time–concentration superposition Master curve Ageing Viscoelasticity Adsorption Entanglement density 

Abbreviations

PEO

Poly(ethylene oxide)

PW

PEO–water solution

PWL

PEO–water–laponite mixture

TTSP

Time–temperature superposition

TCSP

Time–concentration superposition

P

Weight percent of PEO in PWL mixture

W

Weight percent of water in PWL mixture

L

Weight percent of laponite in PWL mixture

c

Weight percent of PEO in aqueous solution

η

Viscosity (Pa s)

\({\mathop \gamma \limits^\cdot }\)

Shear rate (s−1)

ρ

Density (g/cm3)

ω

Angular frequency(rad/s)

G'

Storage modulus (Pa)

G''

Loss modulus (Pa)

aT

Horizontal time-temperature shift factor

bT

Vertical time-temperature shift factor

ac

Horizontal time-concentration shift factor

bc

Vertical time-concentration shift factor

T

Temperature

gi

Relaxation strength (Pa)

λi

Relaxation time(s)

s

Specific surface area of laponite provided for PEO adsorption (m2/mg PEO)

Subscripts—g

Glass transistion

ref

Reference

0

Zero–shear

1 and 2

Level of TCSP in case of PWL mixtures

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.Center for Molecular and Engineering Thermodynamics, Department of Chemical EngineeringUniversity of DelawareNewarkUSA
  2. 2.Hindustan Lever LimitedMumbaiIndia

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