Crystallization Kinetics

Abstract

Crystallization kinetics is the area of polymer science that deals with the rate at which randomly ordered chains transform into highly ordered crystals, and includes every aspect of the resultant structure that is dependent on the route that was taken between those different states. It is a broad and mature area of scientific research, given and uncommon diversity when compared to the crystallization of small molecules because of the wide range of different chemistries and chain topologies that are available to macromolecules. These add layers of comlexity that can make it difficult to find generalizing principles. The article concentrates on principles and observations that have the widest applicability. Crystallizable polymers form semicrystalline materials containing chains or fractions of chains that are trapped in nonequilibrium, amorphous states. Because of this semicrystalline nature, the crystal morphology, rather than the underlying crystal structure, often controls the final properties of a polymer article. Because polymers crystallize so far from equilibrium conditions, a simple examination of the phase diagram gives us little insight into the crystal morphology that is formed or the route that is taken to its formation. To understand, and ultimately control, such behavior, it is necessary to gain an understanding of the kinetics of crystallization, as it is the kinetics of the process that define the structure and properties of the material.

Influence of α′‐/α‐crystal polymorphism on properties of poly(l‐lactic acid)

“…The kinetics of the crystal growth of semicrystalline polymers is usually analyzed by hot‐stage microscopy via measurement of the spherulite growth rate, providing information about the average growth rate of many lamellae as they grow over a distance of several micrometers . As such, it is not the growth rate of an individual lamella, which typically does not exceed a distance much larger than a micrometer, but the growth rate of a semicrystalline superstructure.…”