Model of processing-induced microstructure formation in polymeric materials

• Published in: Journal of polymer science. Part B, Polymer physics Vol. 37; no. 18; pp. 2571 - 2585
• Main Authors: Mendes, L. J., Tsai, T.-C., High, K. A., High, M. S., Tree, D. A.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 15.09.1999; Wiley
• Subjects: Applied sciences; Crystallization; Exact sciences and technology; modeling; Organic polymers; Physicochemistry of polymers; polymer processing; Properties and characterization; structure formation; Kinetic model; Chemical solution; Melt crystallization; Molecular orientation; Structuration; Shear flow; Theoretical study; Polymer; Elongational flow; Modeling
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/(SICI)1099-0488(19990915)37:18<2571::AID-POLB3>3.0.CO;2-L

A general, mechanistic, kinetic model is presented to predict polymer microstructure formation during processing. Applications of the model are presented for three specific cases. The model represents polymer molecules as Kramers chains which may or may not have nucleated. Three forces (hydrodynamic, Brownian, and intermolecular) that act on polymer molecules during processing were considered, which resulted in the presentation of the model as a diffusion equation. The input parameters account for the rheological and thermal history of the polymer melt, the specific type of polymer molecule, and the initial morphology. The solution of the diffusion equation yields a probability distribution function from which the transient and equilibrium morphology can be determined. The three specific cases were chosen to illustrate the versatility of the model and include: the extensional flow‐induced growth of extended chain crystals; the orientation of stiff molecules in solution undergoing shear flow well above the crystallization temperature; and the formation of folded chain vs. extended chain crystals in an extensional flow. Data are available for the first two cases and agree favorably with the model predictions. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2571–2585, 1999