Self-Generated Fields and Polymer Crystallization

Abstract

The creation of thermal, compositional, and stress fields during the crystallization of polymers from the melt is described. The treatment of crystallization under self-generated fields is reviewed, including classical moving boundary problems, the treatment of dendrite growth, and coupled growth. The extension of these treatments to polymer crystallization requires that the velocity of interface motion be defined by the temperature and composition of the melt at the solid−liquid interface, a feature not found in extant analyses suitable for small-molecule systems and metals. Inclusion of this feature renders analytical solutions difficult and usually requires the use of numerical methods. The role of the diffusion length in defining morphological features is described. Methods of simulating the growth of polymer spherulites are reviewed. These include finite element, analytical, and phase field approaches. The role of thermal fields in fiber processing is discussed. Finally, speculations regarding the role of stress fields are presented.

Centimeter-scale giant spherulites in mixtures of polar polymers and crystallizable diluents: Morphology, structure, formation and application

“…44 Schultz reported that coupled growth of mutual propinquity of two phases allows the transformation from liquid to solid much faster than those grown as independent mode. 45 However, what is the origin of the exceptional growth rate? The chain-folding of PAN could be first ruled out, because no PAN lamella has been detected by SAXS (see Fig.…”

About the Art and Science of Visualizing Polymer Morphology using Transmission Electron Microscopy

“…Semicrystalline polymers develop, either by cooling from a quiescent melt or after solvent evaporation, a hierarchical organization consisting of a crystal structure (0.1–1 nm, observable by wide angle X‐ray scattering (WAXS)), organized in lamellae (10–100 nm, accessible by small angle X‐ray scattering (SAXS)), atomic force microscopy (AFM), and TEM. The lamellae develop into microscopic superstructures, in particular spherulites (>1000 nm), visible by optical microscopy or scanning electron microscopy (SEM) consisting of crystalline layers radiating from the spherulite center . Lamellar morphology is a periodic structure of crystalline and amorphous layers.…”

“…The lamellae develop into microscopic superstructures, in particular spherulites (>1000 nm), visible by optical microscopy or scanning electron microscopy (SEM) consisting of crystalline layers radiating from the spherulite center. [8,9] Lamellar morphology is a periodic structure of crystalline and amorphous layers. Constituent chains participate to crystalline lamellae and microphase-separated structures have become increasingly complicated with the development of controlled polymerization, three-dimensional imaging has also been of growing importance.…”

Block-assembling: a new strategy for fabricating conductive nanoporous materials from nanocomposites based on a melt-miscible crystalline/crystalline blend and MWCNTs

“…[57][58][59][60] A number of studies focused on the morphology and crystallization behaviors of melt-miscible crystalline/ crystalline blends have been carefully reviewed by Jungnickel 56 and Schultz. 61,62 PLLA/POM blends are melt-miscible crystalline/ crystalline systems. According to our previous work, PLLA/POM blends exhibit typical lower critical solution temperature (LCST) phase behavior above the melting temperature of the POM.…”