Accession Number : ADA309973

Title :   Development of a New Technique to Monitor Physical Aging of Aircraft Canopy Materials.

Descriptive Note : Final rept.,

Corporate Author : ILLINOIS UNIV AT URBANA FRACTURE RESEARCH LAB

Personal Author(s) : Ivanova, E. ; Chudnovsky, A. ; Bosnyak, C. P.

PDF Url : ADA309973

Report Date : FEB 1996

Pagination or Media Count : 31

Abstract : A new technique to monitor physical aging of aircraft canopy materials has been developed and proposed in this report. It involves the use of photochrome molecules from the class of spiropyrans which, on UV excitation, undergo reversible photochromic conversion to differently colored merocyanine dyes (photoisomerization). The rate of transformation of the merocyanine dye back to the spiropyran in a polymer depends on the segmental mobility and fluctuations of density of the polymer molecules and can be easily followed through their spectral absorbance characteristics. The characteristic relaxation time changes with physical aging of a polymer due largely to densification accompanying the aging process. Thus, employment of photochromes allows quantification of physical aging of polymers. This technique offers a unique, low-cost and non-destructive way to measure the aging without perturbing the system itself. A potential for the development of a portable device for field measurements should be considered as well.

Descriptors :   *AGING(MATERIALS), *MATERIALS, *POLYMERS, *AIRCRAFT CANOPIES, *PHOTOCHROMIC MATERIALS, CONVERSION, PORTABLE EQUIPMENT, DENSITY, MEASUREMENT, ULTRAVIOLET RADIATION, NONDESTRUCTIVE TESTING, MOLECULES, PHYSICAL PROPERTIES, EXCITATION, FIELD TESTS, COLORS, RELAXATION TIME, DYES, IRRADIATION, MERCURY COMPOUNDS, CYANINE.

Subject Categories : Polymer Chemistry
      Aircraft
      Radiation and Nuclear Chemistry
      Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE