Analyzing Petroleum Wax According to ASTM D 4419 - METTLER ...

DSCAnalyzing Petroleum WaxAccording to ASTM D 4419The ASTM D 4419 standard describes the conditions for measuringtransition temperatures of petroleum waxes using differential calorimetryscanning (DSC). The transition temperatures provide petrochemicaltesting laboratories with important information on the quality of petroleumderivatives while the melting peak assists with the characterizationand analysis of petroleum wax.PublisherMettler-Toledo AGLaboratory & Weighing TechnologiesIm LangacherCH-8606 Greifensee, SwitzerlandProductionSegment Marketing LABSwitzerlandTechnical articlesMettler-Toledo AG– Laboratory & Weighing Technologies– Analytical Instruments11794319 40.12DSC is a fast, convenient and reliablethermal analysis technique used for determiningthe characteristic temperaturesof a wax during transitions. Thehighest temperature transition is a solidliquidtransition associated with completemelting. This transition provides a guidefor choosing the most suitable storageand application temperatures. The solidliquidtemperature transition yields informationon the properties of the solid, suchas hardness and blocking temperature.Determining TransitionTemperatures Using DSCThe DSC 1 is a fully automated andversatile tool that can be used to accuratelymeasure transition temperaturesof oil/wax mixtures. The example inFigure 1 demonstrates melting behavior.Five known and two unknown oil/waxmixture samples were pre-melted, stirredand cooled under controlled conditions.Samples were then heated from –60 °C to80 °C at 5 K/min to determine the transitiontemperatures. The results were evaluatedusing the STAR e software and displayedtypical melting behavior with peakmelting temperatures between 46 and57 °C. The two unknown samples couldalso be identified as the DSC curves werecharacteristic for petroleum wax.The oil content of the two unknown sampleswas estimated using a calibrationcurve. This was done by plotting the fiveknown oil contents as a function of themelting enthalpy. Figure 2 shows the excellentlinear relationship between the oilcontent and the overall melting enthalpy.The unknown oil contents of samples 6and 7 (Figure 1) were estimated to be22.4% and 0.6%.The fully automated and versatile DSC 1is an excellent tool for measuring transitiontemperatures of petroleum wax. Withthe wide temperature range, accuracy andoutstanding measurement performance,the DSC 1 offers great benefits to the petrochemicaltesting laboratory.} www.mt.com/dscSubject to technical changes.© Mettler-Toledo AG 08/01Printed in Switzerland. METTLER TOLEDO Testing Labs News 3

Figure 1. Melting of oil/wax mixtures.DSC 1Figure 2. Correlation of enthalpy versus oil contentin oil/wax mixtures.METTLER TOLEDO Testing Labs News 3