Lamellar single crystals of nylon-10,10 crown from a dimethylformamide solution

A new solvent, dimethylformamide (DMF), and the traditional solvent, 1,4-bu tanediol, were used to prepare single crystals of nylon-10,10 from a dilute solution. The lamellae grown from DMF inhabited a more perfect structure a nd regular shape than those crystals crystallized from traditional solvents such as 1,4-butanediol and glycerin. These thin and perfect lamellar cryst als demonstrated patterns of variation in spacing different from those of m elt-crystallized spherulites on heating. Specifically, the two main spacing s slightly separated rather than continuously approaching each other when t he temperature was greater than 180 degreesC. This is a novel phenomenon ob served in nylons. Nevertheless, the usual pattern of change in spacing was observed during the cooling process. These lamellar crystals showed more co mpact spacing of the (002) and (010/100) planes than spherulites at room te mperature. (C) 2001 John Wiley & Sons, Inc.