Neutron and Light Scattering Studies of Compatible Polymer Blends

1986 ◽  
Vol 79 ◽  
Author(s):  
E. W. Fischer
Keyword(s):  
Free Energy ◽  
Light Scattering ◽  
Polymer Blends ◽  
Gibbs Free Energy ◽  
Thermodynamic Description ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

As it is well known the Flory-Huggins approach of the thermodynamic description of a mixture of two polymers A and B leads to an expression [1] for the Gibbs free energy of mixing ΔG

scholarly journals Thermodynamic Analysis of the Formation of FCC and BCC Solid Solutions of Ti-Based Ternary Alloys by Mechanical Alloying

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 510 ◽  
Author(s):  
Claudio Aguilar ◽  
Carola Martinez ◽  
Karem Tello ◽  
Sergio Palma ◽  
Adeline Delonca ◽  
...  
Keyword(s):  
Free Energy ◽  
Mechanical Alloying ◽  
Gibbs Free Energy ◽  
Thermodynamic Analysis ◽  
Solid Solutions ◽  
Ternary Systems ◽  
Solubility Limit ◽  
Ternary Alloys ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

A thermodynamic analysis of the synthesis of face-centred cubic (fcc) and body-centred cubic (bcc) solid solutions of Ti-based alloys produced by mechanical alloying was performed. Four Ti-based alloys were analysed: (i) Ti-13Ta-3Sn (at.%), (ii) Ti-30Nb-13Ta (at.%), (iii) Ti-20Nb-30Ta (wt. %) and (iv) Ti-33Nb-4Mn (at.%). The milled powders were characterized by X-ray diffraction, and the crystallite size and microstrain were determined using the Rietveld and Williamson–Hall methods. The Gibbs free energy of mixing for the formation of a solid solution of the three ternary systems (Ti-Ta-Sn, Ti-Nb-Ta and Ti-Nb-Mn) was calculated using an extended Miedema’s model, applying the Materials Analysis Applying Thermodynamics (MAAT) software. The values of the activity of each component were determined by MAAT. It was found that increasing the density of crystalline defects, such as dislocations and crystallite boundaries, changed the solubility limit in these ternary systems. Therefore, at longer milling times, the Gibbs free energy increases, so there is a driving force to form solid solutions from elemental powders. Finally, there is agreement between experimental and thermodynamic data confirming the formation of solid solutions.

Free Energy of Mixing of Cross-Linked Polymer Blends

Langmuir ◽  
2005 ◽  
Vol 21 (1) ◽  
pp. 240-250 ◽  
Author(s):  
Chowdhury K. Mamun
Keyword(s):  
Free Energy ◽  
Polymer Blends ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

scholarly journals OPTIMIZATION OF DRUG SOLUBILITY USING ASPEN PLUS: ACETYLSALICYLIC ACID (ASPIRIN) SOLUBILITY – A SECOND CASE STUDY

2020 ◽  
pp. 178-184
Author(s):  
KAMAL I AL-MALAH
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Stable Solution ◽  
Aspen Plus ◽  
Liquid Solution ◽  
Flow Sheet ◽  
Molar Gibbs Free Energy ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

Objective: The objective of the study is to optimize the solubility of a drug or a drug-like molecule using Aspen Plus simulation platform. Aspirin (solute) was taken as the second case study. The following solvents were used in our dry (virtual) laboratory experiment: Water, acetone, ethanol, and ethylene-glycol-mono-propyl-ether (PROPGLYC). Methods: A simplified process flow sheet made of a single mixing tank where it has five feed streams, representing the solute, the water, and the set of three organic solvents, and one product stream where aspirin is either solubilized (liquid solution) or remains as solid crystal. Minimization of the molar Gibbs free energy of mixing, ΔGmix, was used as an objective function from an optimization point of view. The Non-random Two-liquid property method was used to analyze the solution properties. Results: Using the molar Gibbs free energy of mixing, ΔGmix, as a criterion of solution thermodynamic stability, it was found that the most stable solution is the quinary mixture made of 24.42% aspirin, 10.22% water, 21.08% acetone, 19.51% ethanol, and 24.77 mole % PROPGLYC. Conclusions: Exploiting Aspen Plus can be extended to handle the solubility of a new drug-like molecule once it is defined within its molecular editor with a little knowledge such as density and/or melting point.

Activity coefficients of NaNO3 in (Mg, Ca, Sr, and Ba)(NO3)2 + H2O systems at 298 K by EMF methods

1993 ◽  
Vol 71 (3) ◽  
pp. 384-389 ◽  
Author(s):  
Stephen N. Smith ◽  
S. Sarada ◽  
Ramamurthy Palepu
Keyword(s):  
Free Energy ◽  
Ionic Strength ◽  
Gibbs Free Energy ◽  
Activity Coefficients ◽  
Interaction Parameters ◽  
Excess Gibbs Free Energy ◽  
Experimental Activity ◽  
Energy Of Mixing ◽  
Total Ionic Strength ◽  
Free Energy Of Mixing

The activity coefficients of NaNO3 in Mg(NO3)2, Ca(NO3)2, Sr(NO3)2 and Ba (NO3)2 were determined at constant total ionic strength of 0.1, 0.5, 0.75, 1.0, 1.5, and 2.0 mol kg−1 at 298 K using EMF methods. The experimental activity coefficients were analyzed using four different formalisms, namely, Reilly–Wood–Robinson, Scatchard, Pitzer, and Harned equations, and the interaction parameters were evaluated. Excess Gibbs free energy of mixing and trace activity coefficients were calculated and the results are discussed.

Sign in / Sign up

Export Citation Format

Share Document