Penetrant diffusion in poly(methyl methacrylate) near T-g: dependence on temperature and polymer weight fraction

Tonge, M.P., Stubbs, J.M., Sundberg, D.C. and Gilbert, R.G. (2000) Penetrant diffusion in poly(methyl methacrylate) near T-g: dependence on temperature and polymer weight fraction. Polymer, 41 10: 3659-3670. doi:10.1016/S0032-3861(99)00597-2


Author Tonge, M.P.
Stubbs, J.M.
Sundberg, D.C.
Gilbert, R.G.
Title Penetrant diffusion in poly(methyl methacrylate) near T-g: dependence on temperature and polymer weight fraction
Formatted title
Penetrant diffusion in poly(methyl methacrylate) near Tg: dependence on temperature and polymer weight fraction
Journal name Polymer   Check publisher's open access policy
ISSN 0032-3861
1873-2291
Publication date 2000-05
Sub-type Article (original research)
DOI 10.1016/S0032-3861(99)00597-2
Volume 41
Issue 10
Start page 3659
End page 3670
Total pages 12
Place of publication Oxford, United Kingdom
Publisher Elsevier
Language eng
Formatted abstract
Forced Rayleigh scattering was employed to measure diffusion coefficients for a ternary system comprising camphorquinone or diacetyl in poly(methyl methacrylate) with methyl isobutyrate as the diluent. Measurements were made at polymer weight fractions, w(p), over the range 0.78-0.90 and temperature 25-50 °C for camphorquinone (which spans the glass transition regime), and at w(p) = 0.9 and 0.95 and at room temperature for diacetyl. Results for camphorquinone show a strong temperature dependence, with diffusion coefficients changing as much as two orders of magnitude between 25 and 50 °C, and showing high activation energies for diffusion ≃125 kJ mol-1 No sharp change in the activation energy for diffusion was observed as the glass transition is crossed. The pre-exponential factor for the diffusion coefficient decreased dramatically through the glass transition. The diffusion coefficients of small penetrants in glassy polymers appear strongly dependent on the molecular size. (C) 2000 Elsevier Science Ltd.

Forced Rayleigh scattering was employed to measure diffusion coefficients for a ternary system comprising camphorquinone or diacetyl in poly(methyl methacrylate) with methyl isobutyrate as the diluent. Measurements were made at polymer weight fractions, wp, over the range 0.78-0.90 and temperature 25-50°C for camphorquinone (which spans the glass transition regime), and at wp = 0.9 and 0.95 and at room temperature for diacetyl. Results for camphorquinone show a strong temperature dependence, with diffusion coefficients changing as much as two orders of magnitude between 25 and 50°C, and showing high activation energies for diffusion≈125 kJ mol-1. No sharp change in the activation energy for diffusion was observed as the glass transition is crossed. The pre-exponential factor for the diffusion coefficient decreased dramatically through the glass transition. The diffusion coefficients of small penetrants in glassy polymers appear strongly dependent on the molecular size.
Keyword Forced rayleigh scattering
Diffusion
Glassy polymers
Holographic grating relaxation
Small molecules
Emulsion polymerization
Glass-transition
Dynamics
Polystyrene
Motion
Probe
Camphorquinone
Coefficients
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemistry and Molecular Biosciences
Centre for Nutrition and Food Sciences Publications
 
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Created: Mon, 07 Mar 2011, 15:58:46 EST