Determination of Temperature-Dependent Coefficients of Viscosity and Surface Tension of Tamarind Seeds (Tamarindus indica L.) Polymer

The rheological properties of tamarind seed polymer are characterized for its possible commercialization in the food and pharmaceutical industry. Seed polymer was extracted using water as a solvent and ethyl alcohol as a precipitating agent. The temperature’s effect on the rheological behavior of the polymeric solution was studied. In addition to this, the temperature coefficient, viscosity, surface tension, activation energy, Gibbs free energy, Reynolds number, and entropy of fusion were calculated by using the Arrhenius, Gibbs–Helmholtz, Frenkel–Eyring, and Eotvos equations, respectively. The activation energy of the gum was found to be 20.46 ± 1.06 kJ/mol. Changes in entropy and enthalpy were found to be 23.66 ± 0.97 and −0.10 ± 0.01 kJ/mol, respectively. The calculated amount of entropy of fusion was found to be 0.88 kJ/mol. A considerable decrease in apparent viscosity and surface tension was produced when the temperature was raised. The present study concludes that the tamarind seed polymer solution is less sensitive to temperature change in comparison to Albzia lebbac gum, Ficus glumosa gum and A. marcocarpa gum. This study also concludes that the attainment of the transition state of viscous flow for tamarind seed gum is accompanied by bond breaking. The excellent physicochemical properties of tamarind seed polymers make them promising excipients for future drug formulation and make their application in the food and cosmetics industry possible.

Fundamentals

The physical and structural fundamentals of polymorphism are introduced, including a review of the phase rule and the thermodynamic relations in polymorphs. The latter are used to introduce energy–temperature diagrams, leading to the definition of the concepts enantiotropism and monotropism describing the thermodynamic relationships between and among polymorphs with appropriate examples. The alternate representation of phase diagram in terms of pressure and temperature is also presented. These lead to a number of rules regarding the relationships between polymorphs and ways to understand and predict some important physical properties: the heat-of-transition rule, the heat-of-fusion rule, the entropy-of-fusion rule, the heat-capacity rule, the density rule, and the infrared rule. Structural aspects include the distinction between crystal form and crystal habit and methods for characterizing and comparing structures in polymorphic systems. Current developments are discussed that deal with the ramifications of nanoscale situations on structural concepts and thermodynamic relationships.

Observation of an apparent first-order glass transition in ultrafragile Pt–Cu–P bulk metallic glasses

An experimental study of the configurational thermodynamics for a series of near-eutectic Pt80-xCuxP20 bulk metallic glass-forming alloys is reported where 14 < x < 27. The undercooled liquid alloys exhibit very high fragility that increases as x decreases, resulting in an increasingly sharp glass transition. With decreasing x, the extrapolated Kauzmann temperature of the liquid, TK, becomes indistinguishable from the conventionally defined glass transition temperature, Tg. For x < 17, the observed liquid configurational enthalpy vs. T displays a marked discontinuous drop or latent heat at a well-defined freezing temperature, Tgm. The entropy drop for this first-order liquid/glass transition is approximately two-thirds of the entropy of fusion of the crystallized eutectic alloy. Below Tgm, the configurational entropy of the frozen glass continues to fall rapidly, approaching that of the crystallized eutectic solid in the low T limit. The so-called Kauzmann paradox, with negative liquid entropy (vs. the crystalline state), is averted and the liquid configurational entropy appears to comply with the third law of thermodynamics. Despite their ultrafragile character, the liquids at x = 14 and 16 are bulk glass formers, yielding fully glassy rods up to 2- and 3-mm diameter on water quenching in thin-wall silica tubes. The low Cu content alloys are definitive examples of glasses that exhibit first-order melting.

Synthesis, Thermal Properties and Decomposition Mechanism of Poly(Ethylene Vanillate) Polyester

Plastics are perceived as modern and versatile materials, but their use is linked to numerous environmental issues as their production is based on finite raw materials (petroleum or natural gas). Additionally, their low biodegradability results in the accumulation of microplastics. As a result, there is extensive interest in the production of new, environmentally friendly, bio-based and biodegradable polymers. In this context, poly(ethylene vanillate) (PEV) has a great potential as a potentially bio-based alternative to poly(ethylene terephthalate); however, it has not yet been extensively studied. In the present work, the preparation of PEV is reported. The enthalpy and the entropy of fusion of the pure crystalline PEV have been estimated for the first time. Additionally, the equilibrium melting temperature has also been calculated. Furthermore, the isothermal and non-isothermal crystallization behavior are reported in detail, and new insights on the thermal stability and degradation mechanism of PEV are given.

GREEN CHEMICAL SYNTHESIS AND PROPERTIES OF SOLID DISPERSIONS OF BENZIMIDAZOLE –Β. NAPHTHOL BINARY DRUG SYSTEM

With view to synthesize and characterize the enhanced pharmaceutical properties of the solid-liquid dispersions of binary drug system through green chemical technique the present communication have been undertaken for detailed investigation of thermodynamic and interfacial properties of benzimidazole (BI) and β. naphthol (βN) binary eutectic and non-eutectic drug dispersions. Eutectic solid dispersion was observed at 0.657 mole fraction of β. naphthol (βN) and at melting temperature 90°C. Thermodynamic quantities; Partial and Integral excess Gibbs energy (gE), excess enthalpy (hE), excess entropy (sE) of eutectic and non-eutectic dispersions were determined with the help of activity coefficient data. The negative deviation from ideal behaviorhas been seen in the system which refers stronger association between unlike molecules during formation of binary mix. The negative value of Gibbs free energy of mixing (DGM) refers the mixing for all eutectic and non-eutectic dispersions is spontaneous. The solid-liquid interfacial characteristics i.e., entropy of fusion per unit volume (DSV), solid-liquid interfacial energy (s), roughness parameter (α), grain boundary energy and roughness parameter (α) of eutectic and non-eutectic solid dispersions have been reported. The size of critical nucleus at different undercoolings has been found in nanoscale, which may be a big significance in pharmaceutical world. The value of roughness parameter, α > 2 was observed which manifests the faceted and irregular growth leads in the system.