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Density and ultrasonic speed measurements have been made, respectively, by means of a densimeter operating in a flow mode and by a sonic solution monitor using a 'sing-around' technique, for aqueous mixtures of 2-(2-methoxyethoxy)ethanol and 2-[2-methoxy(ethoxy),lethanol, at 298.15 K, across the entire composition range. The density values were readily converted to molar volumes, V, and excess molar volumes, VE. Estimates of the isentropic molar quantity, K,, equal to -(aV/ap), , and of its excess counterpart, KE, have been obtained from the density values, in combination with the ultrasonic speed values. The magnitude of VE increases with the introduction of oxyethylene groups into the molecule of amphiphile. The composition dependence of KE shows a similar increase, but one that is limited to the water-rich region. Data reduction procedures have been used to calculate several related quantities leading to graphs with enhanced visual impact. Our results have been compared with those reported earlier for methanol-water, and 2-methoxyethanol-water. Graphical analyses of the data sets are presented in an effort to find a plausible rationale for the observed trends in terms of prevailing patterns of molecular aggregation, while the various excess quantities considered are analysed using a segmented-composition model.

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An analytical technique based on electron spin resonance (ESR) has been developed to estimate the concentration of hindered amine stabiliser additives (HAS) in a polymeric formulation. Our method involves the conversion of the overall HAS derivatives into nitroxyl‐free radicals by exposure of the stabilised polymer to peracetic acid vapour at room temperature. The possibilities of using ESR analysis were explored and we assume that our new ESR method is an easy, accurate and very sensitive method to identify and quantify HAS concentration and to monitor the time course of HAS content in a polymeric formulation.© 2003 Society of Chemical Industry

Summary: Elastomers are very sensitive to oxidative degradation due to the combined effect of light and oxygen. Hence, we investigate the impact of stabilizers on the evolution of molecular structure of elastomers through photo‐oxidation. While a dual processes is generally reported to describe photo‐oxidation of elastomers (oxidation by‐products formation and crosslinking), the aim of the current study is to provide a complete characterization of the efficiency of additives taking into account the dual processes: chemical changes (formation of photoproducts) and molecular structure changes (crosslinking). This work gives new insights about relationships between chemical changes and physical properties evolution of the material through ageing. We conclude that the two phenomenon are correlated to the primary peroxidation reaction and a dual efficiency does not exist for any additive.