Crystallization kinetics of polycapramide

✍ Scribed by Inoue, Masakazu

• Publisher: John Wiley and Sons
• Year: 1961
• Weight: 559 KB
• Volume: 55
• Category: Article
• ISSN: 0022-3832
• DOI: 10.1002/pol.1961.1205516228

✦ Synopsis

Abstract

The kinetics of the isothermal crystallization of polycapramide (nylon 6) is discussed. Temperature changes in specimens during the course of crystallization are measured. For specimens at 200–210°C., the temperature is 2–3°C. higher than that of the crystallization bath. Below 200°C., strict isothermal crystallization cannot be obtained because there are no stable supercooled states. The isothermal crystallization proceeds in two stages. In the first stage, in which the Avrami equation is appliable, n is 4 at temperatures of 210–215°C. and is 2.5 below 207°C.; it changes rapidly between 207 and 210°C. In the second stage, the relaxation of the entanglement of molecules and the perfection of crystals takes place, and the rate of density change increases with crystallization temperature, contrary to the first stage of crystallization. However, the first‐ and second‐stage processes overlap to some degree. Higher molecular weight polymer crystallizes at a lower rate than does low molecular weight polymer. The rate depends on the activation energy of melt flow, and its effect is greater at higher crystallization temperatures. If we assume n equal to 4, log k is in linear relation to T~m~/(Δ__T__)T or T^2^/(Δ__T__)^2^T, where T~m~ is the melting point; T~m~ increases with crystallization temperature, especially above 210°C.