Reexamination of shish kebab formation in poly (ethylene oxide) melt
writer：張麗娜，史偉超，程賀，韓志超
keywords：oriented network, shear induced crystallization, two-step shear
source：期刊
specific source：polymer, 55, 2890-2899
Issue time：2014年
Although recent experiments concerning shear effects on crystallization in polymer melts are inclined to support the oriented network model, two important questions still remain open: the effect of polydispersity on shish formation and the growth mechanism of shish. In this work, a narrowdisperse poly(ethylene oxide) (PEO) is chosen as a model system to clarify the role of polydispersity for shish kebab formation after a pulse of flow. The intact structure of shish kebab observed via scanning electron microscopy (SEM), with a 150nm wide shish core and perpendicular epitaxially grown kebabs with a long period of about 35nm, reveals that polydispersity is not a necessary condition for shish kebab formation. On the other hand, a two-step shear experiment is utilized to elucidate the growth mechanism of shish. It has been proved in a latest study that shish growth is related to the size of the growing nuclei (interval time) and second step shear rate. In this manuscript, a third factor, shear time in the second step shear, is found to be an effective factor to promote the growth of shish, which might provide a convenient processing method.