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(/16ο,.*.) CROSS-SECTION OF TIRE shows tread at top, then breaker cord, breaker and cushion stock, skim stock, car cass cord. CAPTURED GERMAN TIRES ANALYZED BY MEANS OF INFRARED SPECTROSCOPY to determine accurately the percentage com position and type of rubbers. Tests were made by chemists in the Stamford Research La bora tories of American Cyanamid for the Array Ordnance Department, using colorimetric methods using visible light and by infrared spectroscopy. Ten samples of carcass stocks tested showed natural rubber in all cases, varying in amount from 25% to 100%. Of an equal number of tread stocks analyzed, one was wholly natural rubber and nine were pure Buna S. Tubes contained from 75% to 100% natural rubber. The tires were cross-sectioned, photographed, and labeled, as shown here. Wherever possible, samples of the tread, cushion, breaker, and carcass stocks were removed from each tire and subjected to the two analytical procedures. In the first, samples were subjected to an ultraviolet spectrochemical analysis, using a large HilgerE-1 spectrograph, to determine the metal content. Exact values for the phos phorus contents were determined through the use of another spectrochemica! tool, the visible light spectrophotometer. Analysis of the rubber by infrared spectroscopy was based on direct measurement of the strength of absorption bands unique to each component, and by comparison of the infra red absorption spectra of the unknown with those of a series of known prepared standards. (Afar) INFRARED SPECTROSCOPY has proved extraordinarily useful in recent development in the chemistry of hydrocarbons.
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(Above) FIRST STEP IN SAMPLING PROCEDURE was t o cross-section tires and label samples to ensure permanent record and ready identification.
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