Stefan de Goede

Iso-stoichiometric fuel blends: characterisation of physicochemical properties for mixtures of gasoline, ethanol, methanol and water:

When appropriately sourced, bioethanol and biodiesel fuels provide an opportunity for nations to increase their energy independence or to reduce greenhouse gas emissions by supplying energy-dense fuels which are miscible with fossil-derived gasoline and diesel. These fuels can be used in low concentrations in vehicles with no modifications; in the case of ethanol, only minor changes in the fuel system materials together with a low-cost alcohol sensor are necessary for compatibility with a high concentration. Ethanol provides the beneficial property of having a high research octane number which can be exploited at the high-load operating conditions in modern pressure-charged spark ignition engines. However, the availability of sustainable feedstocks constrains the supply of biofuels, and this limits the level at which they are able to displace fossil fuels. The miscibility of methanol with both ethanol and gasoline enables the penetration of alcohols in the fuel pool to be increased. The present work describes the properties of specific mixtures of gasoline, ethanol and methanol which are blended to be iso-stoichiometric and iso-energetic replacements for mixtures of gasoline and ethanol. A simple analytical approach to the formulation of these ternary blends is described on the basis of the volumetric energy density of the pre-blended components, and a number of further physicochemical properties are characterised, including their stoichiometries, vapour pressures, distillation characteristics and propensities to phase separate. Data on the octane numbers of the blends are reported. The properties of quaternary iso-stoichiometric blends of water, gasoline, ethanol and methanol (the so-called hydrous ternary blends) are also examined.

Identifying Important Differences in Mass Spectra Generated by Secondary ion Mass Spectrometry (TOF–SIMS) in a Tribochemical Study

Abstract In order to better understand the lubricating properties of diesel fuel, species that were present on tribological surfaces were investigated using secondary ion time-of-flight mass spectrometry (TOF–SIMS). Traditionally, only certain species that are expected to be present at the interface are investigated and their presence or absence is used to make conclusions regarding the mechanism of lubrication. In this work, an alternative and complementary approach to data analysis and interpretation is proposed, previously demonstrated for TOF–SIMS and based on multivariate analysis methods, where the mass spectral data are investigated more comprehensively. The main objective was to interpret variation within and between different areas of a tested surface and ultimately to contribute to the understanding of the tribochemical reactions that occur at the interface. The validity of this approach was confirmed when the palmitate ion (which would normally be targeted) was shown to contribute significantly (together with other ions) to chemical differences between scratched and unscratched areas of the surface.

Degradation of unstabilised polypropylene and a propene- 1-pentene copolymer

Abstract The degradation of polypropylene (PP) and a propene-1-pentene copolymer (P2) have been monitored with regard to chemical composition, molar mass distribution and chemical composition distribution. The increase in the carbonyl index can be monitored by IR and a decrease in molar mass can be observed from size-exclusion chromatography (SEC). CRYSTAF shows that the chemical heterogeneity of the samples broadens with continuing degradation. SEC-FTIR reveals that the degraded species are mainly found in the low-molecular-weight end of the molar mass distribution. Spatial heterogeneity of the degradation process has been proven by the analysis of abrased layers. It was found that the P2 copolymer degrades at a higher rate compared to PP.