Solid-Solid Phase Transition in Trimethylolpropane (TRMP)

Abstract

An orientationally disordered crystalline (ODIC) plastic phase (γ) was observed in Trimethylolpropane (TRMP) during heating by high resolution thermal and X-ray diffraction analyses. TRMP is a potential thermal energy storage material. The enthalpies of solid-solid (α → γ at 327.8 K) and fusion (γ → liquid at 332.7 K) transitions are 16.36 kJ/mol and 0.9 kJ/mol, respectively. Supercooling was observed during solidification of melts, and this supercooled γ phase began to transform to a metastable crystalline phase, designated as α , after 20 minutes at room temperature. The lattice parameters of the monoclinic α phase, obtained from this study, are: a = 0.8427(5), b = 0.9580(5), c = 0.9185(6) nm, β = 98.958(3) • @ 298 K with Z = 4. The ODIC high temperature FCC γ phase has a lattice parameter: a = 0.9274(3) nm @ 328 K with Z = 4. Differential scanning calorimetry, in-situ Bragg-Brentano X-ray diffractometry, and high temperature and resolution Guinier X-ray diffraction systems were used to determine these phase transitions.

Heat capacity measurement of organic thermal energy storage materials

“…However, this can lead to loss of sensitivity as well as problems associated with baseline heat flow. Chandra et al [17] have conducted a systematic study of the effect of heating rate and sample mass on the resolution of the d.s.c. thermograms for trimethylolpropane [TRMP: (CH 2 OH) 3 C(C 2 H 5 )], an alcohol derivative of neopentane using conventional d.s.c.…”

High-Pressure Raman Spectroscopy of Tris(hydroxymethyl)aminomethane

“…4 Due to the increased freedom of the molecules to reorient on their lattice sites, the heat capacity is also generally higher in the orientationally disordered phase. 5 Owing to the presence of these solid-solid phase transitions with large changes in enthalpy, compounds such as tris(hydroxymethyl)aminomethane (Tris) have been examined for their potential application as thermal energy storage materials, [4][5][6][7] especially for passive solar heating systems for buildings. Materials with solid-solid transitions have the advantage that it is not necessary to provide for the containment of a liquid, 4 as opposed to other materials considered for thermal energy storage which use solid-liquid transitions that have large heats of fusion.…”