Polymorphism of crystalline poly(hydroxymethyl) compounds. VI. The crystal structure of 2‐hydroxymethyl‐2‐nitro‐1,3‐propanediol

Solid-Solid Phase Transition in Trimethylolpropane (TRMP)

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: