Studies on mechanical and swelling behavior of polymer networks on the basis of the scaling concept. 5. Crossover effects above and below the θ temperature

M. Zrínyi, Ferenc Horkay

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Abstract

The temperature dependence of elastic moduli and the equilibrium concentration of swollen poly(vinyl acetate) gels were studied. For gels swollen to equilibrium in a good diluent (toluene), the power law exponent of the elastic moduli, m, was found to be independent of the temperature and to be close to the value predicted by scaling theory. Poly(vinyl acetate) gels equilibrated with isopropyl alcohol in the vicinity of θ temperature were studied. In the crossover regimes (below and above the θ temperature), the apparent power law exponent of the elastic moduli varied between the values of 2.31 and 13.3. At the θ temperature m = 3.04 was obtained. Supposing that the third power of the expansion factor of network chains can be expressed as the ratio of the equilibrium concentration of the gel at θ temperature (φe,θ) to the actual concentration (φe) either below or above θ, it was verified that φe,θe is the only function of τN1/2 (where τ and N are the reduced temperature and the degree of polymerization, respectively). Analysis of the experimental data on the basis of thermal blob theory indicated a satisfactory agreement at N/Nτ > 10; however, at smaller N/Nτ values considerable deviation occurred (Nτ is the temperature-dependent cutoff distance which separates the scales of Gaussian and non-Gaussian behavior within the same chain).

Original languageEnglish
Pages (from-to)2805-2811
Number of pages7
JournalMacromolecules
Volume17
Issue number12
Publication statusPublished - 1984

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Swelling
Polymers
Gels
Temperature
Elastic moduli
2-Propanol
Toluene
Alcohols
Polymerization

ASJC Scopus subject areas

  • Materials Chemistry

Cite this

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title = "Studies on mechanical and swelling behavior of polymer networks on the basis of the scaling concept. 5. Crossover effects above and below the θ temperature",
abstract = "The temperature dependence of elastic moduli and the equilibrium concentration of swollen poly(vinyl acetate) gels were studied. For gels swollen to equilibrium in a good diluent (toluene), the power law exponent of the elastic moduli, m, was found to be independent of the temperature and to be close to the value predicted by scaling theory. Poly(vinyl acetate) gels equilibrated with isopropyl alcohol in the vicinity of θ temperature were studied. In the crossover regimes (below and above the θ temperature), the apparent power law exponent of the elastic moduli varied between the values of 2.31 and 13.3. At the θ temperature m = 3.04 was obtained. Supposing that the third power of the expansion factor of network chains can be expressed as the ratio of the equilibrium concentration of the gel at θ temperature (φe,θ) to the actual concentration (φe) either below or above θ, it was verified that φe,θ/φe is the only function of τN1/2 (where τ and N are the reduced temperature and the degree of polymerization, respectively). Analysis of the experimental data on the basis of thermal blob theory indicated a satisfactory agreement at N/Nτ > 10; however, at smaller N/Nτ values considerable deviation occurred (Nτ is the temperature-dependent cutoff distance which separates the scales of Gaussian and non-Gaussian behavior within the same chain).",
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TY - JOUR

T1 - Studies on mechanical and swelling behavior of polymer networks on the basis of the scaling concept. 5. Crossover effects above and below the θ temperature

AU - Zrínyi, M.

AU - Horkay, Ferenc

PY - 1984

Y1 - 1984

N2 - The temperature dependence of elastic moduli and the equilibrium concentration of swollen poly(vinyl acetate) gels were studied. For gels swollen to equilibrium in a good diluent (toluene), the power law exponent of the elastic moduli, m, was found to be independent of the temperature and to be close to the value predicted by scaling theory. Poly(vinyl acetate) gels equilibrated with isopropyl alcohol in the vicinity of θ temperature were studied. In the crossover regimes (below and above the θ temperature), the apparent power law exponent of the elastic moduli varied between the values of 2.31 and 13.3. At the θ temperature m = 3.04 was obtained. Supposing that the third power of the expansion factor of network chains can be expressed as the ratio of the equilibrium concentration of the gel at θ temperature (φe,θ) to the actual concentration (φe) either below or above θ, it was verified that φe,θ/φe is the only function of τN1/2 (where τ and N are the reduced temperature and the degree of polymerization, respectively). Analysis of the experimental data on the basis of thermal blob theory indicated a satisfactory agreement at N/Nτ > 10; however, at smaller N/Nτ values considerable deviation occurred (Nτ is the temperature-dependent cutoff distance which separates the scales of Gaussian and non-Gaussian behavior within the same chain).

AB - The temperature dependence of elastic moduli and the equilibrium concentration of swollen poly(vinyl acetate) gels were studied. For gels swollen to equilibrium in a good diluent (toluene), the power law exponent of the elastic moduli, m, was found to be independent of the temperature and to be close to the value predicted by scaling theory. Poly(vinyl acetate) gels equilibrated with isopropyl alcohol in the vicinity of θ temperature were studied. In the crossover regimes (below and above the θ temperature), the apparent power law exponent of the elastic moduli varied between the values of 2.31 and 13.3. At the θ temperature m = 3.04 was obtained. Supposing that the third power of the expansion factor of network chains can be expressed as the ratio of the equilibrium concentration of the gel at θ temperature (φe,θ) to the actual concentration (φe) either below or above θ, it was verified that φe,θ/φe is the only function of τN1/2 (where τ and N are the reduced temperature and the degree of polymerization, respectively). Analysis of the experimental data on the basis of thermal blob theory indicated a satisfactory agreement at N/Nτ > 10; however, at smaller N/Nτ values considerable deviation occurred (Nτ is the temperature-dependent cutoff distance which separates the scales of Gaussian and non-Gaussian behavior within the same chain).

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