Crystallization kinetics of polyetheretherketone (PEEK) matrices

TLDR: Differential scanning calorimetry (DSC) and density gradient technique (DGT) were used to determine, both isothermally and dynamically, the crystallization kinetics of polyetheretherketone (PEEK) as mentioned in this paper.

Abstract: Differential scanning calorimetry (DSC) and the density gradient technique (DGT) were used to determine, both isothermally and dynamically, the crystallization kinetics of polyetheretherketone (PEEK). The data were analyzed by a model utilizing, for the first time, two crystal nucleation and growth processes which were observed experimentally in a typical Avrami plot of the isothermal data. Thus, by modeling the data as two separate Avrami type crystallization processes occurring in parallel, both isothermal and dynamic data could be predicted with the same model constants. The first process provided an Avrami exponent of 2.5 and an onset temperature of 320°C. The second process displayed an Avrami exponent of 1.5 and an onset temperature of 342°C. The validity of this dual mechanism crystallization model was proven in practice by predicting with best fit model constants, a wide range of crystallinities of both neat and carbon fiber-reinforced PEEK samples that had been made at different cooling rates from the melt.