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Sol or gel-like behaviour of ideal silica—siloxane mixtures: percolation approach

Authors
Journal
Polymer
0032-3861
Publisher
Elsevier
Publication Date
Volume
33
Issue
13
Identifiers
DOI: 10.1016/0032-3861(92)90451-2
Keywords
  • Silica
  • Percolation
  • Adsorption
  • Poly(Dimethylsiloxane)

Abstract

Abstract Properties of idealized silica—siloxane mixtures are described within the framework of a percolation process. Polymer chains are considered as bifunctional units of percolation. Silica particles are considered as units of percolation with a high functionality, f c ( f c ⋍ 10 2 ); f c is determined by the process of chain adsorption which results from the formation of hydrogen bonds with the silica surface. The state of gelation of a given mixture is characterized by using three variables: the initial specific amount of polymer Q i the specific amount of adsorbed polymer Q r, and the chain molecualr weight M ̄ n . A diagram is proposed to distinguish domains where an infinite cluster is formed from domains in which the clusters formed have a finite size. Expressions of the modulus of elasticity above the threshold of percolation are proposed.

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