DSC in an oxidizing atmosphere

In tests on the higher boiling members of the homologous series of n-alkanes from n-triacontane up to n-hexacontane, two strong peaks are found which are easy to evaluate. These peaks are the LTO peak and the peak in the fuel combustion range. In the range of fuel deposition more than one peak appears. Evaluation of the numerous small peaks is problematic and rarely valuable. Evaluation is normally limited to one or two well-defined peaks. The peak temperatures of eight n-alkanes 

CjgHjoj, CjqHj22) measured in experiments using the same heating rates (j8= 5, 10, 20, 50 K/min), the same air pressure and flow rates are estimated to be equal, as demonstrated by the low coefficients of variation  

The onset temperature of the first peak, characterizing the start of the oxidation reaction, may be considered to be equal within the limits of tolerance  

The HD polyethylenes which may be regarded as long chain n-aUcanes exhibit the same behavior. Their peak temperatures under analogous experimental conditions (at 7 bar) are somewhat higher, however the scattering is very small and independent of molecular weight  

Even the presence of a double bond in a longer carbon chain does not result in a marked change of the peak temperatures. The test on 1-octadecene supplies the following peak temperatures (/3= 10 K/min air 7 bar, 5 cmVmin)  

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