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Phase Diagram Studies on Neopentylglycol and Pentaerythritol-Thermal Energy Storage Materials

Published online by Cambridge University Press:  06 March 2019

Dhanesh Chandra ,
Renee A. Lynch ,
Wei Ding  and
John J. Tomlinson
Dhanesh Chandra
Affiliation:
University of Nevada, Reno Reno, Nevada 89557
Renee A. Lynch
Affiliation:
University of Nevada, Reno Reno, Nevada 89557
Wei Ding
Affiliation:
University of Nevada, Reno Reno, Nevada 89557
John J. Tomlinson
Affiliation:
Oak Ridge National Laboratory Oak Ridge, TN 37831
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Abstract

Pentaerythritol (PE) and neopentylglycol (NPG) are organic molecular crystals which have hydrogen-bonded lattices with layered- and chain-type structures, respectively. The PE undergoes solid-state phase transitions at 416K, from tetragonal to a cubic (γ’) structure and NPG also undergoes this transition at 317K from a monoclinic to a cubic (γ) structure. The phase transitions in binary PE-NPG solid solutions show more than one solid-solid transition in which the NPG-rich β transforms to γ at a constant temperature but the transition of the PE-rich a phase to γ’ passes through a two-phase field at a temperature that varies as a function of composition. Structural analyses by high-temperature x-ray diffractometry have revealed some new, interesting transitions. A phase diagram has been constructed for 0-30 mol% NPG in the PE-NPG system, using x-ray diffraction and differential scanning calorimetry results, and work is in progress to complete this diagram. The variation of lattice parameters as a function of temperature in the α, γ and γ’ phases for PE+20 mol% NPG are presented here, together with a discussion of phase transitions for certain compositions.

Type
Research Article
Information
Advances in X-Ray Analysis , Volume 33: Thirty-Eighth Annual Conference on Applications of X-ray Analysis, July 31 - August 4, 1989 , 1989 , pp. 445 - 452
Copyright
Copyright © International Centre for Diffraction Data 1989

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