Determination of the phase diagram of the binary system C(CH2OH)4–(NH2)(CH3)C(CH2OH)2 by high resolution Guinier diffractometry and differential scanning calorimetry

The phase diagram of the pentaerythritol [(PE): C(CH2OH)4]–2-amino-2-methyl-1,3-propanediol [AMPL: (NH2)(CH3)C(CH2OH)2] ‘plastic crystal’ binary system is presented in this paper. The phase stabilities and boundaries have been determined using high temperature Guinier x-ray diffraction and differential scanning calorimetry. The phase diagram is rather complex with three invariant equilibria: a peritectoid at 357 K, the eutectoid at 423 K, and a peritectic at 457 K. A summary of all the phase transitions occurring in the system, along with the enthalpies of fusion, DSC plots, and high temperature x-ray diffraction patterns is presented.