Thermal transfer simulation regarding the rotational moulding of polyamide 11

Simulation of thermal phenomena in rotational moulding is very important to follow the evolution of the temperature in various zones of this process. It was a question of modelling heat gradients developing in rota-tional moulding part. Thermal model tested take into account the temperature change (thermal transfer mecha-nism) of melting and crystallization pseudo-stages (enthalpy method). Series of tests in polyamide 11 (PA11) were carried out by means of rotational moulding STP LAB, and non-isothermal crystallization kinetics of rota-tional moulding PA11 grade are measured and analysed by DSC technique type TAQ20. A result of non-isothermal crystallization of the studied polyamide was confronted with Ozawa model. In order to test the validity degree of enthalpy method (layer to layer), another approach based on Ozawa model has also been used in the case of cooling pseudo-stage. As results, the rotational moulding of PA11 was successfully carried out. The simulation of the fusion and crystallization stages, by application of Ozawa model coupled with enthalpy method gave a good representation of experimental data

Solid + liquid equilibria and molecular structure studies of binary mixtures for nitrate ester's stabilizers: Measurement and modeling

Solid-liquid equilibria (SLE) data for two binary organic mixtures of N-(2-methoxyethyl)-p-nitroaniline+Nethyl- 4-nitroaniline (S1) and N-(2-ethanol)-p-nitroaniline+N-ethyl-4-nitroaniline (S2) have been measured using differential scanning calorimeter to build the corresponding solid-liquid phase diagrams. The quality of the SLE data has been checked by consistency tests, presenting good quality factors for both systems. Simple eutectic behavior has been observed for these systems with the presence of a solid-solid transition for S2. The SLE data have been correlated by means of Wilson, NRTL, and UNIQUAC equations. The used models calculate the equilibrium temperatures very satisfactorily. The best modeling results were obtained using the Wilson equation with a root mean square deviation between experimental and calculated values for S1 and S2 of 1.15 and 1.99, respectively. The Wilson, NRTL, and UNIQUAC equations have also been used to compute excess thermodynamic functions viz. excess Gibbs energy, enthalpy, and entropy. The obtained results demonstrated a moderate positive deviation to ideality for S1, and a strong positive deviation for S2, unveiling the nature of the interactions between the compounds forming each mixture. In addition, microstructural studies have been carried out by FTIR, XRD and optical microscopy. Weak molecular interactions have been shown for the eutectic compositions. Jackson’s roughness parameter was calculated and found to be greater than 2, suggesting the faceted morphology with irregular structures.The authors are grateful for the financial support of this research from Ecole Militaire Polytechnique (Doctoral Training Program) and from Associate Laboratory LSRE-LCM, Instituto Politécnico de Bragança (projectPOCI-01-0145-FEDER-006984) funded by European Regional Development Fund (ERDF) through COMPETE2020 –Programa Operacional Competitividade e Internacionalização (POCI) – and by national funds through FCT - Fundaçãopara a Ciência e a Tecnologia. C.M.S.S. Neves thanks FCT for the postdoctoral grant SFRH/BPD/ 109057/2015.info:eu-repo/semantics/publishedVersio

Solid–Liquid Phase Equilibria, Molecular Interaction and Microstructural Studies on (N-(2-ethanol)-p-nitroaniline + N-(2-acetoxyethyl)-p-nitroaniline) Binary Mixtures

Differential scanning calorimetry (DSC) is used to investigate the thermal properties of N-(2-ethanol)-p-nitroaniline+N-(2-acetoxyethyl)-p-nitroaniline, and their binary systems. The experimental results demonstrate that the studied binary system presents a simple eutectic behavior and the corresponding mole fraction(xeu)ofN-(2-ethanol)p-nitroaniline at the eutectic point is 0.5486, whereas the temperature (Teu) is found to be equal to 363.6 K. The quality of the solid–liquid equilibria (SLE) data has been checked by thermodynamic consistency tests, presenting good quality factor. The SLE data have been correlated by means of Wilson, NRTL, and UNIQUAC equations. The three models describe satisfactorily the phase diagram as the root-mean-square deviations for the equilibrium temperatures vary from 1.25K to 2.07K. Nevertheless, the Wilson model provides the best correlation results. The three equations have also been used to compute excess thermodynamic functions viz. excess Gibbs energy, enthalpy and entropy. The obtained results revealed a sensitive positive deviation to ideality thus demonstrating the nature of the interactions between the compounds forming the mixture. Microstructural studies have been carried out by FTIR, XRD and optical microscopy showing weak molecular interactions for the eutectic mixture.info:eu-repo/semantics/publishedVersio

Effect of micro- and nano-CuO on the thermal decomposition kinetics of high-performance aluminized composite solid propellants containing complex metal hydrides

In the present work, an attempt has been made to unveil the effect of micro- and nano-particles of copper oxide (µCuO and nCuO) on the thermal decomposition of composite solid propellants (CSPs) based on ammonium perchlorate, hydroxyl terminated polybutadiene and binary fuel mixture of aluminum and lithium tetrahydridoaluminate (AP/HTPB/Al+LiAlH4). The prepared CSPs were analyzed by different analytical techniques. The second part of the study was devoted to the kinetic modeling of the thermal decomposition process of the fabricated CSPs samples. In the light of the obtained results, it was concluded that the use of µCuO and nCuO accelerated the decomposition of CSPs. Moreover, the incorporation of nCuO to the LiAlH4-based propellant increased substantially the heat release and decreased the average activation energy compared to the baseline samples. Moreover, the decomposition reaction mechanisms of the investigated propellant samples have clearly changed through the incorporation of nano- and micro-CuO

Isothermal Vapor Pressures of Three Binary Systems: n -Tetradecane + Methyl Dodecanoate, Methyl Tetradecanoate, or Methyl Hexadecanoate between 353.15 and 453.15 K

International audienceIsothermal vapor pressures of three binary systems, methyl dodecanoate (1) + n-tetradecane (2); methyl tetradecanoate (1) + n-tetradecane (2); and methyl hexadecanoate (1) + n-tetradecane (2), were measured by means of a static apparatus at temperatures between 353.15 and 453.15 K. The data of the pure components were correlated by the Antoine equation. A maximum azeotropic behavior is observed for the binary mixture, methyl dodecanoate (1) + n-tetradecane (2). The molar excess Gibbs energies GE were deduced from Barker’s method by fitting the experimental points through Redlich–Kister equation. The NRTL and UNIQUAC models were applied to regress the experimental vapor liquid equilibrium (VLE). The investigated systems were successfully represented by the two models