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NCJ Number: 148187 Find in a Library
Title: RECOVERY OF ERASED NUMBERS IN POLYMERS
Journal: Journal of the Forensic Science Society  Volume:34  Issue:1  Dated:(January-March 1994)  Pages:11-16
Author(s): H Katterwe
Date Published: 1994
Page Count: 6
Type: Report (Study/Research)
Format: Article
Language: English
Country: United Kingdom
Annotation: This paper reports on experiments designed to reveal erased numbers in recently developed and technically more significant polymers.
Abstract: Experiments with acoustic microscopy at an ultrasonic frequency of 50 MHz were unsuccessful; however, experiments that used swelling techniques with various solvents, relief polishing, and heat treatment were successful. The experiments revealed that thermomechanically treated regions of a polymer have a higher swelling capacity under the influence of solvents than untreated regions. Results show that polymers have a "mechanical memory." The heating process showed similar "memory effects" to those observed by Hosemann et al during experiments on the deformation of polyethylene. Apparently, each crystallite is transformed by stretching into microcrystallites that lie together like a string of pearls and form parts of the so-called ultrafibrils of the stretched material. The domains may only regain their original shape near the melting point if the microcrystallites are interconnected by chain molecules that do not lose this contact during the stretching process. The tie molecules are able to raise the entropy of the colloidal structure to the highest possible value, and the sample returns to its original shape. 4 figures and 14 references
Main Term(s): Science and Technology
Index Term(s): Erased identification restoration; Forensic sciences; Investigative techniques; Police; Polymer analysis
Note: Based on a paper presented at the Forensic Science Society meeting in Lyon, May 1991.
To cite this abstract, use the following link:
http://www.ncjrs.gov/App/publications/abstract.aspx?ID=148187

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