Mechanism and kinetics of ultra‐high molecular weight polytetrafluoroethylene sintering. Issue 21 (2nd June 2014)

• Record Type: Journal Article
• Authors: Ganguly, Ranadip; Lesser, Alan J.
• Is Part Of: Journal of applied polymer science. Volume 131:Issue 21(2014:Nov. 05)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2014-06-02
• Subjects: Polymers -- Periodicals; Polymerization -- Periodicals; 668.9
• DOI: 10.1002/app.40967
• Languages: English
• ISSNs: 0021-8995

Abstract

<abstract abstract-type="main"> <title>ABSTRACT</title> <p>The effect of sintering time on the melt evolution of Ultra‐High Molecular Weight Polytetrafluoroethylene was studied <italic>in situ</italic> by high temperature Wide Angle X‐ray Scattering, and by cyclic thermal loading profiles within a Differential Scanning Calorimeter (DSC) and Thermo‐Mechanical Analyzer (TMA). Results obtained from these techniques support the concept of molecular ordering in the melt state as a function of sintering time well above the melting temperature. TMA, which is not a conventional technique for monitoring thermal transitions, is shown to be sensitive enough for such purposes. Both DSC and TMA exhibit nonequilibrium melt behavior even 30°C above its equilibrium melting temperature for long time periods. A correlation between the DSC and TMA results is established. The cyclic thermal profile leads to a dramatic growth in enthalpy of crystallization/melting. The mechanism for this growth is associated with two independent processes; isothermal annealing at the sintering temperature and lamellar thickening in the solid state. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. <bold>2014</bold>, <italic>131</italic>, 40967.</p> </abstract>