Accession Number : AD0690612

Title :   MECHANICS OF VISCOELASTIC COMPOSITES.

Descriptive Note : Final rept. 1 Mar 68-29 Feb 69,

Corporate Author : AKRON UNIV OHIO

Personal Author(s) : Gent,A. N. ; Hilyard,N. C. ; Kanakkanatt,S. V.

Report Date : MAY 1969

Pagination or Media Count : 53

Abstract : An apparatus was developed to measure the dynamic mechanical properties of foamed materials filled with a viscous fluid, over a frequency range from 0.002 to 200 Hz. It has been tested using two model viscoelastic materials over the temperature range -50C to +100C. Measurements were then made on various foam/fluid systems including rubber latex, polyether and polyester foams filled with air, glycerin, silicone oil and water. The Gent-Rusch theory has been modified to take into account inertia effects, damping in the matrix material itself, and special features of the test-piece assembly. The modified theory is shown to describe the measurements successfully over the entire frequency range employed. Stress-optical coefficients have been determined for lightly-cross-linked samples of cis- and trans-polyisoprene, swollen to a high degree in a variety of non-polar solvents. A strong dependence on the geometrical asymmetry of the solvent molecule has been observed. Solvents with long straight molecules gave large values of the stress-optical coefficient whereas those with compact symmetrical molecules gave minimum values. This effect is attributed to short-range orientational order, due to packing effects in a molecularly-anisotropic medium. (Author)

Descriptors :   (*COMPOSITE MATERIALS, *ELASTOMERS), (*EXPANDED PLASTICS, *VISCOELASTICITY), (*ISOPRENE, *PHOTOELASTICITY), MECHANICAL PROPERTIES, SYNTHETIC RUBBER, POLYESTER PLASTICS, VIBRATION, DAMPING, CROSSLINKING(CHEMISTRY), STEREOCHEMISTRY, MOLECULAR STRUCTURE, BIREFRINGENCE, ORGANIC SOLVENTS, GELS, COMPOSITE PROPELLANTS

Subject Categories : Laminates and Composite Materials
      Elastomers and Rubber

Distribution Statement : APPROVED FOR PUBLIC RELEASE