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Journal of Materials Science

, Volume 26, Issue 16, pp 4281–4284 | Cite as

Characterization of molecular orientation by differential scanning calorimetry

Part 1 Tg-TLL region for amorphous polymers
  • M. G. Rogers
Papers

Abstract

Differential scanning calorimetry was used to study relaxations occurring above the glass transition, Tg for a number of characterized and fabricated polystyrenes. Part 1 of this study examines the liquid-liquid relaxation temperature, TLL; Part 2 the effects of injection moulding and biaxial orientation of polystyrene; and Part 3 deals with the effects of injection blow moulding.

The rubbery plateau region was found to be bounded by the glass transition, Tg, and a weak transition or relaxation, TLL, found above Tg as an endothermic slope change in the base line. In some cases, this transition could be enhanced as a step change when molten samples were quenched in liquid nitrogen.

The effect of molecular weight on Tg and TLL was similar, and had the relationships TLL/Tg=1.07+0.03 forMinw/Mn ≃1, and TLL/Tg=1.15 ± 0.01 for ¯MwMn > 1.

Keywords

Differential Scanning Calorimetry Polystyrene Glass Transition Calorimetry Base Line 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1991

Authors and Affiliations

  • M. G. Rogers
    • 1
  1. 1.Research and DevelopmentDow Chemical Canada Inc.SarniaCanada

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