Kinetics of mesophase formation and crystallization in poly(diethylsiloxane)

• Published in: Journal of polymer science. Part B, Polymer physics Polymer physics, 1987-09, Vol.25 (9), p.1859-1884
• Main Authors: Papkov, V. S., Svistunov, V. S., Godovsky, Yu. K., Zhdanov, A. A.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Structure, morphology and analysis
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/polb.1987.090250907

Optical and calorimetric studies of the kinetics of mesophase formation and crystallization in poly(diethylsiloxane) have been conducted. The mesomorphic phase is found to grow from the isotropic melt in the form of lamellar domains about 2 μm thick in the temperature range 293–307 K. According to birefringence data, macromolecules in the mesomorphic lamellae are perpendicular to the end faces. The kinetics of mesophase formation obey the Avrami equation with the morphological parameter n close to 2 (it is equal to 1.75 ± 0.05), which corresponds to the two‐dimensional growth of the mesomorphic phase from athermal nuclei. The limiting conversion of the isotropic melt was shown to be temperature‐dependent. This is likely to be connected with a change in the number of nuclei with temperature. The crystallization of polymer from the mesomorphic state occurs with retention of the optical texture of the sample. The process proceeds not as a sporadic crystallization of individual mesomorphic lamellae but as a growth of the nucleated crystalline regions via a consecutive incorporation of adjacent crystallizing lamellae.