Solution crystallization of TPI is relatively less concerned, though the crystallization kinetics from solution is profoundly related to the advance in fraction purification and the precipitation polymerization of TPI. In this work, isothermal crystallization of TPI from its solutions with varied concentrations and solvents at temperatures ranged from -20 degrees C to 30 degrees C were studied to attain the kinetic parameters and crystal forms. The solubility curves of TPI in the solvents and the conversion temperatures between isothermal and non-isothermal crystallization were supplied to propose the available concentrations and temperatures for TPI isothermal crystallization. In most cases, the kinetics of TPI crystallization was subject to the Avrami-equation, revealing as the crystallization rate of TPI increase with TPI concentration but decrease with crystallization temperature (T-c) though few deviations arising from the influence of non-isothermal crystallization and transient nucleation were also observed under several special conditions. The better quality solvents of TPI, like THF and toluene exhibited the relatively slower crystallization rate. The alpha form of TPI crystals was found to appear as samples crystalized from heptane and THF. (C) 2018 Elsevier Ltd. All rights reserved.