Dynamics of Hairy-Rod Polymer Solutions in Simple Shear Flow: Aging Effects

• Tipo: Artigo em Revista Científica Internacional
• Data: 2000

Autores

Loic Hilliou (Autor) FEUP; Dimitris Vlassopoulos (Autor) Outra; Matthias Rehahn (Autor) Outra

Revista

Título: Macromolecules

Vol. 33 Nº 8

Páginas: 3105-3110

ISSN: 0024-9297

Editora: American Chemical Society

Classificação Científica

FOS: Ciências da engenharia e tecnologias

Outras Informações

DOI: 10.1021/ma991212n

Abstract (EN): We investigated the dynamics of solutions of a model hairy-rod polyester using optical rheometry and find that in the concentrated regime significant time effects dominate its response in simple shear flow. They are characterized by an enhanced viscosity and shear thinning behavior, accompanied by a corresponding increase of the absolute value of the induced birefringence and the relevant relaxation time upon cessation of shear. However, the most dramatic effect is the change of sign and large increase of the absolute value of the birefringence, signifying the dominance of form effects, associated with the formation of large anisotropic aggregates at longer times, which are oriented in the vorticity direction. This observation of anomalous birefringence is in qualitative agreement with the theoretical approach of Cates who considered a presmectic local (anisotropic) ordering resulting from the interplay of particle interactions and the external field.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 6