Enthalpy relaxation of styrene-maleic anhydride (SMA) copolymers. 2. Blends with poly(methyl methacrylate) (PMMA)

N R Cameron, John Mackenzie Grant Cowie, Roderick Ferguson, I J McEwan

Research output: Contribution to journalArticle

Abstract

The enthalpy relaxation of miscible blends of styrene-maleic anhydride (SMA) copolymers and poly(methyl methacrylate) (PMMA) has been studied, and the enthalpic data modelled using the Cowie-Ferguson (CF) semi-empirical approach. The blend behaviour in each case was not predictable from the concentration of each component. For the blend with the lower MA content copolymer (SMA2/PMMA), the enthalpy lost by the fully relaxed glass was greater than for either component, whereas the higher MA content copolymer blend (SMA4/ PMMA) aged in a manner very similar to PMMA itself. In each case, the blends relaxed more slowly than their components and the distribution of relaxation times was broader. This implies that each blend has a lower free volume than its components; however, this conflicts with the enthalpic data for SMA2/PMMA. Reasons for this apparent contradiction are given. It is likely that concentration fluctuations are present in the SMA4/PMMA blend, suggested by a broad transition range at Tg, which may explain its slower relaxation behaviour. © 2001 Elsevier Science Ltd.

Original languageEnglish
Pages (from-to)6991-6997
Number of pages7
JournalPolymer
Volume42
Issue number16
DOIs
Publication statusPublished - Jul 2001

Keywords

  • Enthalpy relaxation
  • Poly(methyl methacrylate)
  • Styrene - Maleic anhydride

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