Accession Number:

AD0643847

Title:

SURFACE VISCOSITY OF POLYDIMETHYLSILOXANE MONOLAYERS.

Descriptive Note:

Interim rept.,

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s):

Report Date:

1966-09-23

Pagination or Media Count:

11.0

Abstract:

The surface viscosities of a series of polydimethylsiloxanes were studied using a canal viscometer as well as a torsional surface viscometer. The siloxane monolayers investigated had molecular weights ranging from 520 to approximately 105,000 and included both the ethoxy and trimethyl end-blocked polymers. The surface viscosity of even the highest molecular weight polydimethylsiloxane monolayer was extremely low, below the limit of sensitivity of the canal viscometer, which is of the order of 0.0001 surface poise. This surface viscosity is remarkably low when compared with monolayers of other polymeric materials that have been studied at the waterair interface. Many of these polymers such as poly-e-capramide 6-Nylon, the proteins, and synthetic polypeptides have given highly viscous, or viscoelastic, non-Newtonian films even at film pressures of only a few dynescm. The low surface viscosity of the siloxanes reflects the relatively low intermolecular cohesion that exists between adjacent siloxane chains in a monolayer. This low surface viscosity may in part explain the defoaming and antifoaming ability of the polydimethylsiloxane fluids. Author

Subject Categories:

  • Miscellaneous Materials
  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE