The isothermal crystallization kinetics of ethyl cellulose /poly(ethylene oxide)/ ethyl cellulose sandwich films

Isothermal crystallization of the sandwich films in the form of ethyl cellulose/poly(ethylene oxide)/ethyl cellulose (EC/PEO/EC) was traced by differential scanning calorimeter (DSC). A primary turning point was found in the Avrami plot and the Avrami analysis shows that the primary turning point is an indication of transformation of crystal growth geometry from the three-dimensional mode to the two-dimensional one. A mathematical model was proposed to predict if the primary turning point would emerge in the Avrami plot. The model is related to an expression that involves the sample thickness and the average distance between adjacent nuclei. The presence of the primary turning point and the prediction of the model were confirmed by using the computer simulation method.