NCJ Number
214497
Journal
Journal of Forensic Sciences Volume: 51 Issue: 3 Dated: May 2006 Pages: 586-596
Date Published
May 2006
Length
11 pages
Annotation
This study assessed the application of infrared chemical imaging to the analysis of bicomponent fibers, which are a special class of man-made fibers composed of two polymers of different chemical and/or physical properties within the same filament.
Abstract
The authors of this study conclude that infrared chemical imaging is capable of revealing both a fiber's chemical composition and spatial configuration with a single measurement. In 6 of the 11-bicomponent fiber samples, infrared chemical imaging succeeded in exposing 2 spectroscopically distinct regions when the fibers were examined side-on. In addition to producing characteristic infrared spectra for each component, infrared chemical imaging produced images that clearly revealed the side-by-side configuration of these components in the fiber. A cross-section of the fiber was prepared and imaged in one case, but generally the preparation of fiber cross-sections was difficult. For 5 of the 11 samples, the infrared spectra identified the overall chemical composition of the fibers as determined from a published classification scheme; however, the fiber components could not be spatially resolved. In analyzing bicomponent fibers, infrared chemical image analysis encountered the same difficulties inherent in conventional "single-point" infrared spectroscopy, such as interference fringing and sloping baselines, particularly when analyzing acrylic-type fibers. A number of infrared sampling techniques were tried in an effort to overcome these problems. Few other techniques can provide this information without any prior knowledge of the fiber's bicomponent nature and the configuration of its components. More research is required, however, before using this method in routine casework. The descriptions of materials and methods cover sample details, conventional testing (microscopic techniques and environmental scanning electron microscopy), and the application of infrared chemical imaging to the samples. 1 table, 10 figures, and 18 references