Thermal analysis of raw and aged linseed oil
DOI:
https://doi.org/10.5935/1809-2667.20090006Keywords:
Linseed, Oxidation, OilAbstract
Linseed oil is a natural oil and consists primarily of triacylglycerol containing high percentage of polyunsaturated fatty acids. Its physical and chemical properties change during the process of oxidation. Many studies have been performed to understand the oxidative process that occurs in vegetable oils and to determine the compounds formed during auto-oxidation of these materials. The Thermogravimetry (TG), Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC) have been used mainly to study the thermal stability of materials and fuel. However, they are scarce in the study of thermal behavior of linseed oil, being widely used in production of pictorial material. Thus, an evaluation was carried out to verify the thermal behavior of natural linseed oil and this oil artificially aged by TG / DTA and DTG in dynamic atmosphere of synthetic air and nitrogen. Results showed that in an atmosphere of nitrogen, samples decompose in a stage between 30°C and 490°C, with loss of approximately 95% of the initial mass. In dynamic atmosphere of synthetic air samples react with oxygen and the gas and decomposed in three stages between 150 ° C and 550 ° C forming 4.5% (mass) of residue. The difference in the process of decomposition is related to the complexity of the matrix and the mechanisms involved in the auto-oxidation of oil. The infrared spectra (IR) of these samples show that several oxygenated compounds are formed during aging of the oil.Downloads
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