By optical microscopy, scanning calorimetry, thermogravimetry, and computer simulation the homogeneous reaction phase and the nucleation of macromolecular crystals of LiPO3 from the monomeric LiH2PO4 melt was studied. A reaction mechanism is proposed and the concentrations of oligomer species are calculated as a function of time at 276,290, and 300 °C. Rate constants and activation energies are determined. The dimer formation has a rate constant 200 times larger than the rate constant for further oligomerization. The nucleation is athermal and is shown to involve oligomer species of 4.5 nm length or more. The nucleation density was found to be almost constant between 276 and 575°C.
Lithium polyphosphate crystals produced by crystallization during polymerization and crystallization from the polymer melt were analyzed by thermal analysis. The glass‐transition and melting temperature, heat of fusion, and entropy of fusion were found to be 336°C, 651.5°C, 21 kJ/mole, and 23 J/deg mole, respectively. Crystallization from the macromolecular melt was followed by thermal analysis, x‐ray diffraction, and electron and optical microscopy. It could be shown that chain folding may be the first step to crystallization from the macromolecular melt. Oligomers could not effectively nucleate crystallization. Lithium polyphosphate is shown to present a prime example of the processes involved in crystallization during polymerization and macromolecular melt crystallization.
The crystal growth of LiPO3 from the polymerizing LiH2PO4 melt is studied using optical nicroscopy, thermogravimetry, electron microscopy and model calculations. It is shown that the linear crystal growth rate is constant at a given temperature and has an activation energy of 110kJ/mole. The major molecule involved in the simultanous crystallization during polymerization, which leads to extended chain crystals, is the dimer.
Reaktionsphase und Keimbildung makromolekularer LiPO3 meren LiH2PO4‐Schmelze wurden mit "optischer Mikroskop trie, Thermogravimetrie und Modellrechnungen untersucht.
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