Determination of thermophysical properties of prototypes of tin-lithium alloy by differential scanning calorimetry

This paper presents a description of research works to determine the thermophysical properties of a tin-lithium alloy with a different percentage of lithium and tin atoms in the alloy. The method of differential scanning calorimetry (DSC) was used for the studies, by which the thermophysical properties of the alloy (temperature of phase transition and enthalpy) were determined. The work was carried out at the TiGrA experimental complex. Studies to determine the enthalpy and temperature of phase transition of prototypes of tin-lithium alloy were carried out in the temperature range from 150°C to 500°C at a heating rate of 10°C/min. The experiments were carried out with a pristine sample of tin (reference) and prototypes of a tin-lithium alloy, the percentage of lithium in which was 20, 25 and 27 at. %. As a result of the work performed, the melting point of the prototypes was determined, which was 224°C and 218°C. The values of the specific heat of fusion (enthalpy) of the investigated alloys were determined, which amounted to 76.5 J/g, 80.7 J/g and 86.3 J/g, respectively.

Photocatalytic Degradation of High Density Polyethylene using CaO Nanocatalyst

The photodegradation of high density polyethylene (HDPE) using CaO nanoparticles as a catalyst was carried out using 500 W lamp. After exposure, morphology as well as thermal properties of the HDPE was investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). SEM results showed that the HDPE is more prone to crack into small fragments, which indicated a rise in crystallinity with different amounts of catalyst i.e. CaO nanoparticles. The DSC results confirmed the remarkable influence of photodegradation on degree of crystallinity (XC%), fusion enthalpy (ΔH J g-1) and melting temperature (Tm) of HDPE. Infrared spectrometry (FTIR) demonstrated all functional groups of HDPE, present before and after photodegradation. Overall results showed that HDPE was photodegraded into small fragments successfully by using CaO nanopartilces, where different functional groups such as carbonyl, esters and vinyl were obtained during chain scission.

The effect of different wall materials on the production of suppressed-pungent capsaicin microparticles

The aim of this study was to investigate the effects of wall materials types on the production of double-layered and suppressed-pungent capsaicin microparticles via spray chilling method. For this purpose, palm oil and different proteins (gelatin, sodium caseinate and whey protein) were used as wall materials, while soy lecithin was selected as stabilizer. Sample encapsulated only with palm oil (single-layered) was used as control. Centrifuge stability and kinetic stability were analyzed on the prepared emulsions. Total and surface capsaicin, microencapsulation efficiency, melting point temperature and fusion enthalpy analysis were carried out on the capsaicin microparticles obtained by spray chilling.Keywords: Capsaicin; Spray chilling method; Pungency; Double-layered microparticles

Pharmaceutical salts of emoxypine with dicarboxylic acids

New salt forms of the antioxidant drug emoxypine (EMX, 2-ethyl-6-methylpyridin-3-ol) with pharmaceutically acceptable maleic (Mlt), malonic (Mln) and adipic (Adp) acids were obtained {emoxypinium maleate, C8H12NO+·C4H3O4 −, [EMX+Mlt], emoxypinium malonate, C8H12NO+·C3H3O4 −, [EMX+Mln], and emoxypinium adipate, C8H12NO+·C6H9O4 −, [EMX+Adp]} and their crystal structures determined. The molecular packing in the three EMX salts was studied by means of solid-state density functional theory (DFT), followed by QTAIMC (quantum theory of atoms in molecules and crystals) analysis. It was found that the major contribution to the packing energy comes from pyridine–carboxylate and hydroxy–carboxylate heterosynthons forming infinite one-dimensional ribbons, with [EMX+Adp] additionally stabilized by hydrogen-bonded C(9) chains of Adp− ions. The melting processes of the [EMX+Mlt] (1:1), [EMX+Mln] (1:1) and [EMX+Adp] (1:1) salts were studied and the fusion enthalpy was found to increase with the increase of the calculated lattice energy. The dissolution process of the EMX salts in buffer (pH 7.4) was also studied. It was found that the formation of binary crystals of EMX with dicarboxylic acids increases the EMX solubility by more than 30 times compared to its pure form.

Effect of Hybrid Fillers on the Thermal Properties of UHMWPE/Chitosan-ZnO Composites

In this work, UHMWPE reinforced composites containing hybrid zinc oxide (ZnO) and chitosan particles were prepared via the hot compression technique. The effect of ZnO contents (10, 20, 30 wt.%) and chitosan contents (1, 2, 3 wt.%) on the thermal properties of UHMWPE/ZnO and UHMWPE/Chitosan-ZnO reinforced composites were successfully investigated using DSC and TGA analysis, respectively. Based on DSC results, both UHMWPE/ZnO and hybrid composites did not record significant changes in the melting temperatures (Tm). The heat fusion enthalpy (Hm) and degree of crystallinity (Xc) of hybrid composites were found to be higher than UHMWPE/ZnO composites. As the TGA results shown, hybrid composites were also found to have higher thermal stability than UHMWPE/ZnO composites at 10 % and 50 % weight loss level. Overall, the UHMWPE/ZnO + 3 wt.% Chitosan hybrid reinforced composite recorded comparable mechanical properties and better thermal properties than neat UHMWPE.

Molecular dynamics study of the effect of alkyl chain length on melting points of [CnMIM][PF6] ionic liquids

Experimental trends in melting points correctly captured by simulation and the opposite trends were found to be the results of the balance between fusion enthalpy and fusion entropy.