Pre-Crystallization Criteria and Triple Crystallization Kinetic Parameters of Amorphous-Crystalline Phase Transition of As40S45Se15 Alloy

This framework focuses mainly on a detailed study of the pre-crystallization criteria that characterize the As40S45Se15 glassy alloy in various heating rates ranging from 5 to 40 (K/min.) by DSC thermo-grams in the range of (300-575 K). These criteria aim to clarify the relationship of the tendency of glass-forming by the heating rate for the investigated glassy alloy. As well, the present framework demonstrates the criteria of thermal stability. Continuously, the various nucleation and growth pathways. The transformation in activation energy with the volume of the crystalline portion was deduced and, through this, we were able to determine the surface resistance of the analyzed bulk alloy in the crystallization region. The crystalline structure of the study sample was recognized by X-ray diffraction (XRD) and electron scanning microscope (SEM).

Degradation behaviour in vitro of poly L-lactic acid (PLLA)/polycaprolactone (PCL) masterbatch

In order to prepare the absorbable medical textile material with different degradation rates, two biopolymers of poly L-lactic acid (PLLA) and polycaprolactone (PCL) with different degradation rates, were mixed in different proportions, and made into PLLA/PCL masterbatch. The experiment of degradation in vitro was conducted to reveal the degradation behaviour of PLLA/PCL masterbatch, and the characteristics of masterbatch in degradation, such as surface morphol- ogy, chemical structure, crystallization, mass loss and strength, were analyzed. The results indicated that the surface of PLLA/PCL masterbatch was etched in degradation, and the larger proportion of PCL, the less etching and slower degra- dation. The ester bonds were hydrolyzed firstly, and the crystallization region in PLLA/PCL masterbatch was destroyed gradually to form a non-crystalline region in degradation. The degradation rate of PLLA in composite masterbatch was faster than that of PCL. With increasing of PCL involved in masterbatch, the mass loss rate of masterbatch in degrada- tion decreased. In addition, the more PCL involved in composite masterbatch, the lower breaking strength.

THE ROLE OF COMBINED MOLTEN SALTS IN SODIUM-CERIUM (III) ORTHOPHOSPHATE CRYSTALLIZATION

The efficient crystallization conditions for high temperature synthesis of sodium-cerium(III) orthophosphate from binary molten salts have been investigated in a light of influence of the inert reaction media addition. Taking into consideration NaF and Na2MoO4 as an addictives to a convention phosphate melt the crystallization regions of CePO4 and Na3Ce(PO4)2 have been identified by means of IR spectroscopy and powder X-Ray diffraction methods. The initial Na/P ratio in the melt has been shown to play the key role in pure Na3Ce(PO4)2 phase formation. The concentration of NaF has been chosen as 20–60 mol. % and MoO3 in a range of 30–60 mol. %, while the cerium(III) content has been maintained equal to 10 mol. %. Additional application of NaF or Na2MoO4 lowers the temperature from 1400 in comparison to Na4P2O7 flux to 1000°C and homogenization time from 12 to 1h., respectively. Thus, the optimal conditions for the high-temperature growth has been found to be Na/P = 1.67 and NaF content equal to 30–45% mol. in case of fluoride-containing systems, and Na/P> 4,00 with MoO3 content of 25–36% mol for a molybdate one. In case of both fluoride and molybdate addition the crystallization region of the target compound has been bordered by a wide area of CePO4 phase. Three crystallization regions has been estimated during crystallization process: CePO4, Na3Ce(PO4)2 and a wide field of their co-crystallization. With Na/P ratio in the binary melt there is a simultaneous change in the solids structure prepared. Thus, when CePO4 possesses highly condensed CeO8 polyhadra in the framework and crystallizes at lower Na/P ratio, Na3Ce(PO4)2 corresponds to isolated CeO8 moieties that are stabilized under higher Na/P values. Within the synthetic conditions investigated, the melts have shown to play a depolymerizing role for the phosphate chains found in the melt, leading to crystallization temperature lowering in initial melt. The approach proposed for the of Na3Ce(PO4)2 synthesis allows to expand the temperature range of its formation and to carry out its uniform doping with fluorescent activators to modify its characteristic spectrum for the needs of modern inorganic LEDs.

The Ternary System Phase Equilibrium of KCl-NH4Cl-H2O at 80°C

The ternary system of solid-liquid phase equilibrium relation of KCl-NH4Cl-H2O was studied at 80 °C. The solubility data of KCl and NH4Cl in water were obtained by isothermal equilibrium method, and the phase diagram of the system was plotted. The result showed that this system exist six phase regions: i.e. the unsaturated solution region, pure KCl , pure NH4Cl, the solid solution base of KCl, the solid solution base of NH4Cl and their common crystallization region with the solid solution base of KCl and the solid solution base of NH4Cl crystallization regions. Some crystallization area will be changed with the various temperature, According to the phase diagram, it can be calculated the quantity of evaporated water in the crystallization process of KCl-NH4Cl-H2O and controlled the change of concentration in the evaporation process preferably.