Development of a new hydrocarbon index for oil-in-water

A new robust method for determination of hydrocarbons in water without use of Freon(TM) or other halogenated solvents has been validated and subjected to an interlaboratory exercise. The method is based on extraction with a light hydrocarbon (boiling point in the 39-69 degrees C range), followed by cleanup for removal of polar components and detection by gas chromatography (GC) with flame ionisation (FID) detection. The performance characteristics of the method are comparable with that of the previous Freon-IR method with recoveries in the 60-80% range and reproducibility (between laboratory variations) of about 30%. A screening method for hydrocarbons in the range 5 ppm and above based on infrared spectroscopy (IR), and a promising method for detection of low levels based on solid phase extraction (SPE) has been tested and validated. (C) 1999 Elsevier Science Ltd. All rights reserved

Photoemission study of the copper/poly(ethylene terephthalate) interface

The metallization of poly(ethylene terephthalate) (PET) by copper has been studied by photoelectron spectroscopy (x-ray and vacuum ultraviolet). The results are interpreted in the light of a valence-effective-Hamiltonian band-structure calculation on the PET polymeric chain and by comparison with earlier work on copper oxides. The theoretical valence-band density of states is in very good agreement with the photoelectron spectra of PET and allows us to present a detailed interpretation of the valence electronic structure of PET. Upon metallization, we find that, for low coverages (<5×1014 Cu atoms/cm2) copper binds preferentially to the oxygen from the carbonyl (—C—O) and the ether (—C—O—) groups of the PET. At coverages near 7.5×1014 Cu atoms/cm2, the additional copper remains metallic and gives rise to a three-dimensional islandlike growth mode. The low reactivity towards PET stands in sharp contrast to the case of other transition metals, like Ti and Cr

Multitechnique Approach of the Surface-analysis of Fluorinated Polyethylene Terephthalate

Polyethylene Terephthalate 12-mu-m thick films (Mylar(R)) have been subjected to an industrial gaseous fluorination treatment. The chemical surface modifications of the treated films have been studied with the aid of various surface sensitive techniques (ISS, SSIMS and XPS); thanks to the complementarity of these techniques, the chemical reaction scheme at the surface is emphasized. The ISS technique provides the elemental chemical composition of the first topmost monolayer. In the case of polymers, it is thought that the low carbon sensitivity of ISS is due to the shielding of the carbon atoms by the hydrogen atoms. ISS spectra obtained on fluorinated PET samples show that the fluorination treatment results in the incorporation of fluorine with a slight change of the O/C ratio: this has been interpreted by the substitution of hydrogen atoms from the PET by fluorine which has already been observed on other polymers subjected to the same treatment. Both XPS and SSIMS analyses confirm these results. First, the SSIMS spectra obtained on the fluorinated samples are totally different from those obtained on the untreated PET samples: these spectra exhibit new peaks characteristic of fluorine containing molecular ions similar to those observed from fluorinated polymers such as PVDF or PTFE. Since the secondary ions formation involves ruptures of the polymer chains and some recombination reactions, it is difficult to decide from SSIMS on the exact sites on the PET chains where the hydrogen substitution by fluorine takes place. This was made possible with the help of XPS: the shape of the C1s peak after fluorination of the PET shows that the formation of new CF(x) species (x less-than-or-equal-to 2) occurs on the electron rich benzenic rings of PET rather than on the aliphatic parts of the PET chains. Finally, RBS has been used in order to estimate the depth at which the fluorination treatment has proceeded: this has been estimated to a few tenths of micrometer