Accession Number:

ADA038912

Title:

Scanning Electron Microscopy of Rubber Tear.

Descriptive Note:

Final rept., 1 Oct 76-1 Mar 77,

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s):

Report Date:

1977-04-01

Pagination or Media Count:

24.0

Abstract:

A simple technique was devised for SEM observation into tears or cuts in rubber or other flexible polymers. A rectangular specimen about 2 x 1 x 0.5 cm was held in a bent configuration in a SEM holder and a shallow razor cut made at the top of the bend. Tensile stresses cause the rubber to tear and advance the cut depth. Observing along the tearing direction the highly stressed rubber at the tear tip damage zone could be observed in detail. A number of commercial rubbers including natural, nitrile, neoprene, polybutadiene and fluorocarbon compositions were examined using this technique. Initially, the stressed rubber at the tear tip was more or less continuous although some structure and occasionally cavitation were observed at high magnifications 5000X. Removal of the specimens from the microscope and exposure to laboratory air resulted in gradual 2-20 hr development of an open network of fibers and nodules, due to oxygenozone attack on the stressed rubber. The process resembled the slow relaxation of a stretched film of a highly viscous liquid under the action of surface forces. The rate of the network formation was generally proportional to the oxidation resistance of the rubber. The significance of these observations is discussed in reference to the practice of cyclizing rubber surfaces as a pretreatment for adhesive bonding. Author

Subject Categories:

  • Elastomers and Rubber

Distribution Statement:

APPROVED FOR PUBLIC RELEASE