Advertisement

The European Physical Journal E

, Volume 4, Issue 2, pp 173–182 | Cite as

Dielectric relaxation of poly(ethylenglycol)- b-poly(propylenglycol)-b-poly(ethylenglycol) copolymers above the glass transition temperature

  • S. Moreno
  • R.G. Rubio
  • G. Luengo
  • F. Ortega
  • M.G. Prolongo

Abstract:

The complex dielectric permittivity has been measured for three poly(ethylenglycol)-b-poly(propylenglycol)-b-poly(ethylenglycol) copolymers with different content of poly(ethylenglycol) (15%, 33% and 80%), and increasing degree of crystallinity (0%, 10% and 20%, respectively). Only the non-crystalline sample shows the normal mode relaxation together with the segmental (α-relaxation) and the Johari-Goldstein (β-relaxation) modes. The crystalline samples show also polarization contributions due to the existence of interfaces between the crystallites and the amorphous phase. The relaxation times of the (α and normal modes can be described by a VFT equation with the same value of T0. There is a slowing-down of the segmental mode due to the presence of crystallites. The temperature dependence of the α and β relaxations in the copolymers is very similar to that found in pure PPG, while there are significant differences in the case of the normal mode of the non-crystalline sample. The size of the cooperatively rearranging regions CRR, and the width of the glass transition region increase slightly with the degree of crystallinity. The temperature dependence of the size of CRRs is compatible with the prediction of fluctuation theory. No systematic effect of the degree of crystallinity on the β-relaxation has been found. Near Tg the β-relaxation time is close to the primitive time of the coupling model.

PACS. 64.70.Pf Glass transitions – 77.22.Gm Dielectric loss and relaxation 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Copyright information

© EDP Sciences, Springer-Verlag, Società Italiana di Fisica 2001

Authors and Affiliations

  • S. Moreno
    • 1
  • R.G. Rubio
    • 1
  • G. Luengo
    • 2
  • F. Ortega
    • 1
  • M.G. Prolongo
    • 3
  1. 1.Departamento de Quımica Fısica I, Facultad de Quımica, Universidad Complutense, 28040 Madrid, SpainES
  2. 2.L'Oréal, Centre Charles Zviak, Clichy Cedex, FranceFR
  3. 3.Departamento de Materiales y Producción Aeroespacial, E.T.S.I. Aeronáuticos, Universidad Politécnica, 28040 Madrid, SpainES

Personalised recommendations