NCJ Number
225596
Journal
Journal of Forensic Sciences Volume: 53 Issue: 6 Dated: November 2008 Pages: 1334-1343
Date Published
November 2008
Length
10 pages
Annotation
Since the self-heating of a vegetable oil due to an auto-oxidation of its fatty acids has been reported in the literature as the cause of many fires, this study evaluated differential scanning calorimetry (DSC) as a technique for determining the thermodynamics associated with various vegetable oils, particularly their propensity toward self-heating.
Abstract
This study demonstrated the usefulness of calorimetric analyses in evaluating the self-heating propensity of a questioned oil. The results obtained by applying DSC to various types of oil not only showed that the self-heating ability of an oil correlated with its degree of unsaturation, but also that the influence of additives could be critical. Thus, nonisothermal DSC analysis is a fast, simple, and reliable method of testing the oxidizability and exothermic reaction propensity of real oil products made from pure oil mixed with additives. By comparing DSC curves obtained under oxidizing and inert atmospheres, such as air and nitrogen, respectively, this method proved to be sensitive and capable of determining self-heating variability among oils. Five different vegetable oils were used in this study: edible linseed oil, boiled linseed oil, safflower oil, corn oil, and peanut oil. The selection of these oils was based on the degree of their saturation, which is often linked to their propensity for self-heating. Samples of the different oils were prepared for calorimetric measurements conducted by DSC, which is a thermal microanalytical technique that records thermal changes in a sample while being subjected to temperature variations. This article describes the DSC technique in detail as it was used in measuring and comparing the various oils’ propensity to self-heat. 8 figures, 3 tables, and 43 references