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The role of molecular weight and temperature on the elastic and viscoelastic properties of a glassy thermoplastic polyimide
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Whitley, Karen S. Gates, Thomas S. Nicholson, Lee M. |
| Copyright Year | 2001 |
| Description | Mechanical testing of the elastic and viscoelastic response of an advanced thermoplastic polyimide (LaRC-SI) with known variations in molecular weight was performed over a range of temperatures below the glass transition temperature. The notched tensile strength was shown to be a strong function of both molecular weight and temperature, whereas stiffness was only a strong function of temperature. A critical molecular weight was observed to occur at a weight average molecular weight of M, approx. 22,000 g/mol below which, the notched tensile strength decreases rapidly. This critical molecular weight transition is temperature-independent. Low, molecular weight materials tended to fail in a brittle manner, whereas high molecular weight materials exhibited ductile failure. Furthermore, low molecular weight materials have increased creep compliance and creep compliance rate, and are more sensitive to temperature than the high molecular weight materials. At long timescales (less than 1100 hours) physical aging serves to significantly decrease the creep compliance and creep rate of all the materials tested. Low molecular weight materials are less influenced by the effects of physical aging. |
| File Size | 1147557 |
| Page Count | 22 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20010021135 |
| Archival Resource Key | ark:/13960/t3033sq8k |
| Language | English |
| Publisher Date | 2001-02-01 |
| Access Restriction | Open |
| Subject Keyword | Nonmetallic Materials Viscoelasticity Creep Properties Performance Tests Ductility Glass Brittleness Glass Transition Temperature Tensile Strength Sensitivity Low Molecular Weights Polyimides Stiffness Elastic Properties Thermoplasticity Failure Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
