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Onset temperature, polymer glass formation

The onset of glass formation in a polymer melt is associated with the development of orientational correlations that arise from chain stiffness. At the temperature Ta, there is a balance between the energetic cost of chain bending and the increased chain entropy, and below this temperature orientational correlations are appreciable while the melt still remains a fluid. Such a compensation temperature has been anticipated based on a field theoretic description of semiflexible polymers by Bascle et al. [120]. The temperature 7a is important for describing liquid dynamics since the orientational correlations (and dynamic fluid heterogeneities associated with these correlations) should alter the polymer dynamics for T < Ta from the behavior at higher... [Pg.163]

A close connection exists between the presence of a flexible polymer skeleton and the flexibility of the bulk material. Macromolecular flexibility is often defined in terms of the glass-transition temperature, Tg. Below this temperature, the polymer is a glass, and the backbone bonds have insufficient thermal energy to undergo significant torsional motions. As the temperature is raised above the Y g, an onset of torsional motion occurs, such that individual molecules can now twist and yield to stress and strain. In this state the polymer is a quasi-liquid (an elastomer) unless the bulk material is stiffened by microcrystalfite formation. Thus, a polymer with a high Tt is believed to have a backbone that offers more resistance to bond torsion than a polymer with a low 7 g. [Pg.106]


See other pages where Onset temperature, polymer glass formation is mentioned: [Pg.186]    [Pg.200]    [Pg.204]    [Pg.164]    [Pg.201]    [Pg.217]    [Pg.238]    [Pg.417]    [Pg.558]    [Pg.240]    [Pg.442]    [Pg.121]    [Pg.122]    [Pg.497]    [Pg.174]    [Pg.87]    [Pg.2732]    [Pg.154]    [Pg.213]    [Pg.397]    [Pg.504]    [Pg.355]    [Pg.392]    [Pg.105]    [Pg.584]    [Pg.269]   
See also in sourсe #XX -- [ Pg.131 ]




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Glass formation

Glass formation temperature

Onset temperature

Polymer glass formation

Polymer glasses

Polymer temperature

Polymers glass temperature

Temperature formation

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