Crystallization kinetics were used to develop a spherulite growth model, which can determine local crystalline distributions through an optimization algorithm. Kinetics were used to simulate spherulite homogeneous nucleation, growth, and heterogeneous nucleation in a domain discretized into voxels. From this, an overall crystallinity was found, and an algorithm was used to find crystallinities of individual spherulites based on volume. Then, local crystallinities within the spherulites were found based on distance relative to the nucleus. Results show validation of this model to differential scanning calorimetry data for polyether ether ketone at different cooldown rates, and to experimental microscopic images of spherulite morphologies. Application of this model to various cooldown rates and the effect on crystalline distributions are also shown. This model serves as a tool for predicting the resulting semi-crystalline microstructures of polymers for different manufacturing methods. These can then be directly converted into a multiscale thermomechanical model.
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http://dx.doi.org/10.3390/ma17143411 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
The University of Tennessee Knoxville, Chemistry, UNITED STATES OF AMERICA.
Polymers (Basel)
November 2024
Department of Organic and Polymer Materials Chemistry, Tokyo University of Agriculture and Technology, Koganei-shi, Tokyo 184-8588, Japan.
We investigated the crystallization kinetics and morphology evolution of miscible crystalline/crystalline blends of poly(trimethylene terephthalate) (PTT) and poly(ethylene terephthalate) (PET) during isothermal melt crystallization. The integrated light-scattering intensity and the spherulite size increased gradually and then steeply as crystallization progressed in 70/30 PTT/PET at 215 °C, indicating the two-step crystallization behavior. The compact PET spherulite grew in the first step, and the dendritic PTT spherulite grew in the second step, forming the double spherulite consisting of a PET component in the inner region and a PTT one in the outer region.
View Article and Find Full Text PDFJ Phys Chem B
December 2024
Interdisciplinary Center for Transfer-oriented Research in Natural Sciences (IWE TFN), Martin Luther University Halle-Wittenberg, 06099 Halle/Saale, Germany.
The kinetics of homogeneous crystal nucleation and the stability of nuclei were analyzed for a random butylene succinate/butylene adipate copolymer (PBSA), employing Tammann's two-stage crystal nuclei development method, with a systematic variation of the condition of nuclei transfer from the nucleation to the growth stage. Nuclei formation is fastest at around 0 °C, which is about 50 K higher than the glass transition temperature and begins after only a few seconds. Due to the high nuclei number, spherulitic growth of lamellae is suppressed.
View Article and Find Full Text PDFChemistry
November 2024
Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, 7610001, Israel.
The branched metal-organic frameworks (MOFs) are the first superstructures of this kind, and the growth mechanism may explain crystal shapes of other materials. The mechanism of the formation of fascinating structures having a hedrite, sheaf or spherulite appearance are detailed. The branching can be controlled, resulting in crystals that either exhibit multiple generations of branching or a single generation.
View Article and Find Full Text PDFActa Crystallogr B Struct Sci Cryst Eng Mater
December 2024
Department of Chemistry and Bioengineering, Graduate School of Engineering, Osaka Metropolitan University, 3-3-138 Sugimoto Sumiyoshi-ku, Osaka 558-8585, Japan.
Sublimation methods utilizing the surface properties of substrates can address the challenge of controlling hollow morphologies in rod crystals. Spherulites were formed on the hydrophilic surface of the (0001) planes of α-quartz and sapphire substrates by sublimation of 1,2-bis(3,5-dimethyl-2-thienyl)perfluorocyclopentene (1a). Various types of hollow morphologies, distinguished by the size and shape of their cross sections and by the presence or absence of branching structures, were formed separately on α-quartz and sapphire substrates.
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