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Summary In this paper we present excess molar volumes and excess molar enthalpies of binary and ternary mixtures containing propyl propanoate, hexane and cyclohexane as components at 298.15 K. Excess molar volumes were calculated from the density of the pure liquids and mixtures. The density was measured using an Anton Paar DMA 60/602 vibrating-tube densimeter. Excess molar enthalpies were obtained using a Calvet microcalorimeter

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Artificial ageing of double base rocket propellant

Effect on dynamic mechanical properties

Journal of Thermal Analysis and Calorimetry
Authors: S. Matečić Mušanić and M. Sućeska

Abstract  

The ageing of double base rocket propellants (DB rocket propellants), which is a consequence of chemical reactions and physical processes that take place over time, has significant effect on their relevant properties (e.g. chemical composition, mechanical properties, ballistic properties, etc.). The changes of relevant properties limit the safe and reliable service life of DB rocket propellants. This is the reason why numerous research efforts are devoted to finding out reliable methods to measure the changes caused by ageing, to assess the quality at a given moment of time, and to predict remaining life-time of DB rocket propellants. In this work we studied dynamic mechanical properties of DB rocket propellant artificially aged at elevated temperatures, in order to detect and quantify changes in dynamic mechanical properties caused by the ageing. Dynamic mechanical properties were studied using dynamic mechanical analyser (DMA). The results obtained have shown that the ageing causes significant changes of DMA curve’s shape and positions. These changes are quantified by following some characteristic points on DMA curves (e.g. glass transition temperatures; storage modulus, loss modulus and tanδ at characteristic temperatures, etc.). It has been found out that the most sensitive parameters to the ageing process are: storage modulus at viscoelastic and softening region, peak width and height on loss modulus curve, glass transition and softening temperature, and tanδ at viscoelastic region.

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Abstract  

Instrumental neutron activation analysis (INAA) was used to determine trace elemental contamination in bird feathers. Primary feathers from twelve mallard (Anas platyrhynchos) ducks, migrating through the Thousand Islands region of Ontario, Canada, were analyzed for selenium, mercury, chromium, arsenic and antimony. Certified reference materials were used to assess the quality of the analytical procedure. Quantification of chemical elements was performed using Ortec Gamma Vision software. Five chemical elements were quantified, with corresponding analytical uncertainties of less than 20%. Results indicated the presence of As (max = 0.13 mg kg−1), Cr (max = 2.6 mg kg−1), Hg (max = 7.7 mg kg−1), Sb (max = 0.31 mg kg−1) and Se (max = 1.31 mg kg−1). To assess the validity of using INAA as a quantitative analytical technique for feather samples, two standard reference materials were examined and mercury results were compared to those obtained from both direct mercury analysis (DMA) and cold vapour atomic absorption spectroscopy (CVAAS). Several CVAAS results differed significantly from the INAA results; in many instances CVAAS appeared to under-report when compared to INAA, with relative percent difference values as high as 126%. Conversely, results obtained using DMA compared favourably with INAA. For all samples, RPD values were within 30%. This is the first study to use INAA to examine feather contamination in Canadian migratory waterfowl and the first to corroborate INAA feather results by comparing them to those obtained using CVAAS and DMA.

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Abstract  

Sensitivities for the measurement of four arsenic species, AsIII, AsV, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), in environmental waters and rice extracts by a new neutron activation analysis (NAA) method using pre-separation of the species by liquid chromatography were determined. A manual fraction collection was used to isolate the species, followed by instrumental neutron activation analysis procedures. The sensitivities determined for arsenic species in the samples varied from 1.21 to 1.47 ng per vial or about 30 μg·L−1 in sample solutions which translates to about 900 ng arsenic per gram of rice for our HPLC-NAA experiments.

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Thermodynamic properties of the ternary system MTBE+1-propanol+hexane

Application of different group contribution models and empirical methods

Journal of Thermal Analysis and Calorimetry
Authors: M. M. Mato, S. M. Cebreiro, P. V. Verdes, J. L. Legido, and M. I. Paz Andrade

Summary Experimental excess molar enthalpies and excess molar volumes of the ternary system x 1MTBE+x 21-propanol+(1-x 1-x 2) hexane and the involved binary mixtures have been determined at 298.15 K and atmospheric pressure. Excess molar enthalpies were measured using a standard Calvet microcalorimeter, and excess molar volumes were determined from the densities of the pure liquids and mixtures, using a DMA 4500 Anton Paar densimeter. The UNIFAC group contribution model (in the versions of Larsen et al., and Gmehling et al.) has been employed to estimate excess enthalpies values. Several empirical expressions for estimating ternary properties from experimental binary results were applied.

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Summary Experimental densities for the ternary mixture x 1MTBE+x 21-propanol+(1-x 1-x 2)decane and the binary mixtures xMTBE +(1-x)1-propanol and x1-propanol+(1-x)decane have been measured at 298.15 K and atmospheric pressure, using a DMA 4500 Anton Paar densimeter. Excess molar volumes were determined from the densities of the pure liquids and mixtures. Attending to the symmetry of the studied mixtures, suitable fitting equations have been used in order to correlate adequately the experimental data. For the ternary mixture, experimental data were also used to test several empirical expressions for estimating ternary properties from experimental binary results.

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Thermal and dynamic mechanical properties of carbon dioxide and propylene oxide alternative copolymer, poly(propylene carbonate) (PPC), and the end-capped PPC with maleic anhydride were investigated by means of TG and DMA. A master curve of the storage modulus vs. frequency can be deduced from the isochronal curves. Physical parameters of both plain and MA end-capped PPC were discussed. The results showed that for maleic anhydride (MA) end-capping PPC, an improvement of its thermal stability and mechanical properties accompanied with some modifications of the viscoelastic behavior were obtained.

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Ternary mixture MTBE+1-pentanol+nonane at 298.15 K and atmospheric pressure

Measurements and analysis of densities and excess molar volumes

Journal of Thermal Analysis and Calorimetry
Authors: P. Verdes, M. Mato, J. Legido, and M. Paz Andrade

Abstract  

Densities at 298.15 K and atmospheric pressure have been measured, using a DMA 4500 Anton Paar densimeter, for the ternary mixture methyl tert-butyl ether (MTBE)+1-pentanol+nonane and for the involved binary mixture 1-pentanol+nonane. In addition, excess molar volumes were determined from the densities of the pure liquids and mixtures. Suitable fitting equations have been used in order to correlate adequately the excess molar volumes. Experimental data were also used to test several empirical expressions for estimating ternary properties from experimental binary results.

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Abstract  

Calorimetric and volumetric investigations of ovalbumin salting by sodium chloride, lithium chloride, potassium chloride, lithium sulfate and ammonium sulfate buffered solutions in the range of concentrations of about 0.2–1.2 M of salts are reported. The evolution of enthalpies and apparent molar volumes vs. salts concentration was investigated using ITC MicroCal titration microcalorimeter and Anton Paar DMA 60/602 digital densimeter. It was found that the changes in enthalpies of salting and apparent molar volumes follow a similar trend. Conclusions about the ability of salts: to precipitate ovalbumin solution are presented.

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Abstract  

Cellulose acetate-based polycaprolactones (CAPCL's) were synthesized by the polymerization of -caprolactone which was initiated by non-substituted OH group in cellulose acetate. The CL/OH (mol mol–1) ratios of the CAPCL's were changed from 2 to 20. Thermal and viscoelastic properties of the CAPCL sheets were studied by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Glass transition, cold crystallization and melting were determined by DSC. Dynamic modules (E'), dynamic loss modules (E'') and tan were measured in a temperature range from –150 to 50°C by DMA. Apparent activation energy of a dispersion was calculated from the frequency dependency of E'' peak temperature. It was found that the main chain motion of both CA and PCL is observed in a CL/OH ratio from 0 to 10 mol mol–1. However, when CL/OH ratio exceeds 10 mol mol–1, the crystalline region which is rearranged by the PCL chain association is observed and only the main chain motion of PCL can be detected.

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