Advanced avrami formula and its application to describing the isothermal crystallisation of polymers

IF 3.1 2区化学 Q2 CHEMISTRY, ANALYTICAL Thermochimica Acta Pub Date : 2025-02-04 DOI:10.1016/j.tca.2025.179950

László Mihály Vas , Emese Slezák , Kolos Molnár , Ferenc Ronkay

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Abstract

The classic Avrami formula has widely been used to describe and characterize the crystallisation process of polymers. We showed that the Avrami formula is not correct for the random nucleation. To eliminate this and some problems of fitting the Avrami formula with integer exponent revealed in the literature, we modified the Avrami equation and derived a new extended formula that can describe instantaneous and random (time-dependent) nucleation simultaneously. This formula may give information on the crystalline structure of both types of nuclei; moreover, it makes it possible to determine the crystalline fraction developed from the instantaneous nuclei. The latter enables us to estimate, for example, the effect of nucleating agents numerically on the crystallisation process and the ultimate crystallinity. The applicability of the new formula was validated by performing isothermal crystallisation tests on poly(ethylene-terephthalate) (PET), polypropylene (PP), low- and high-density polyethylene (LDPE and HDPE) samples at various temperatures, which resulted in a better fit characterized by the much smaller relative maximum absolute error (0.4–2.9 %) related to that for the Avrami equation (1.9–15.9 %).

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来源期刊

Thermochimica Acta 化学-分析化学

CiteScore

6.50

自引率

8.60%

发文量

210

审稿时长

40 days

期刊介绍： Thermochimica Acta publishes original research contributions covering all aspects of thermoanalytical and calorimetric methods and their application to experimental chemistry, physics, biology and engineering. The journal aims to span the whole range from fundamental research to practical application. The journal focuses on the research that advances physical and analytical science of thermal phenomena. Therefore, the manuscripts are expected to provide important insights into the thermal phenomena studied or to propose significant improvements of analytical or computational techniques employed in thermal studies. Manuscripts that report the results of routine thermal measurements are not suitable for publication in Thermochimica Acta. The journal particularly welcomes papers from newly emerging areas as well as from the traditional strength areas: - New and improved instrumentation and methods - Thermal properties and behavior of materials - Kinetics of thermally stimulated processes