Title

Chemical Stress Relaxation Measurements Of Polyurethanes

Date

1962

Index Abstract

Contrails only

Photo Quality

Incomplete

Report Number

WADD TR 61-71

Creator

Chlystak, S. J.

Peterson, E. A.

Harrah, L. A.

Parker, J. A.

Corporate Author

Armstrong Cork Company

Laboratory

Directorate of Materials and Processes

Extent

104

Identifier

AD0282837

AD0282837

Access Rights

OTS

Distribution Classification

1

Contract

AF 33(616)-7088

DoD Project

7360

DoD Task

73615

DTIC Record Exists

Yes

Distribution Change Authority Correspondence

None

Report Availability

Full text available by request

Date Issued

1962-05

Abstract

Three cast solid polyurethane elastomers, designated AF-1, AF-2, and AF-3, constituted with different numbers and kinds of cross-links were prepared from precisely characterized prepolymers and cross-linking processes.

These three polymers were designed to include the various types of linkages that normally occur in the conventional solid propellant binders formulated from polyurethanes. They were adjusted with respect to physical properties to make them more amenable to a preliminary investigation. In addition to special characterizations performed, the conventional physical properties of these elastomers were determined.

These polymers were used to investigate chemorheological stress relaxation and to evaluate its efficiency in characterizing the reliability of polyurethane materials with regard to thermal and mechanical stability.

A complete literature search and annotated bibliography of stress relaxation phenomena was prepared.

The equipment necessary to perform reproducible and reliable continuous and intermittent stress relaxation measurements on high modulus polyurethane was constructed and tested. As a result of preliminary observations made, some modifications and engineering changes were necessary to obtain these reliable data.

Both continuous and discontinuous stress relaxation measurements in standard 1/4" tensile specimens at temperatures of 100°C., 125°C., and 150°C. were made.

The rates of scission of these three different kinds of cross-linked polyurethanes were measured and the activation energies, assuming normal Maxwellian decay for these processes, was determined. These correlate qualitatively with the different polymer structures investigated.

Preliminary high-speed stress-strain analysis of these polymers was performed to observe their behavior at shock loading conditions. An unusual inversion of the relative ranking of the modulus as a function of testing rate and total strain was observed.

Block specimens of these polyurethane polymers were prepared and conditioned at the stress relaxation conditions. These were provided for the parallel contract on ultrasonic testing techniques being conducted by Sperry Products Company, Danbury, Connecticut.

Specimens of loaded prototype solid propellants were obtained from the Elkton Division of the Thiokol Chemical Company for similar tests.

Subject

Solid Rocket Propellants

Elastomers

Measurement

Polymers

Propellants

Shear Stresses

Stability

Stresses

Thermal Stresses

Ureido ( N-C( O)-N )

Publisher

Wright-Patterson Air Force Base, OH : Directorate of Materials and Processes, Aeronautical Systems Division, Air Force Systems Command

Distribution Conflict

No

Type

report

Provenance

Lockheed Martin Missiles & Fire Control