In this study, pure polylactic acid (PLA) and composite polylactic acid/ curcumin (PLA / Cur) were prepared by a suspension of ultrasonically agitated micrometer-sized curcumin powder, which was mixed with chloroform solvent under slow mechanical stirring and incorporated into the PLA. The resulting suspension was used to cast free-standing PLA / Cur composite films. The filler content was chosen to be 2.0 wt % curcumin. Physical properties (glass transition, temperature, mechanical and thermodynamic) were analyzed by Positron Annihilation Lifetime Spectroscopy (PALS), which is a unique tool for analyzing the defects of polymer materials. The free volume and holebility of PLA and PLA / Cur were studied in vacuum and temperature range of 283 to 353 K. Ortho-positronium (o Ps), life , and intensity were measured as more sensitive parameters to determine free volume dimensions. The results of the thermodynamic property of PLA, examined with PALS technique, revealed a phase change of around 58 ºC. Also, an improvement was observed in the PLA / Cur structure with the addition of curcumin, by reducing nano-size defects.
In this study, the structure of polyethylene glycol polymer with different molecular weights was investigated, and the physical properties were studied in terms of pressure, volume and temperature using a theory called Simha-Somcynsky (SS). which shows irregular lattice structure in terms of the hole fraction depending on which thermodynamic quantities are expressed in the statistical thermodynamics of polymers. Therefore, it is necessary to determine the hole fraction and occupied site fraction y. Thermodynamic properties and hole fraction were investigated in the range of temperature between 283 -450 K, and at a pressure up to 150 MP. Average error and maximum error in specific volume were determined as 0.036% and 0.28%, respectively, as the highest error in peg302. The other important determination was that the polyethylene glycol had glass transition temperatures ranging from 55 to 60 K.
The Gradient energy coefficient () in polymers and oligomers (a few segments) play an important role in polymer blending, wetting, coating, adhesion process, foaming and a comprehensive role in the description as well as understanding of many processes especially in innovation of new polymer with classification of materials. As a result, the main reason in this study appear which has how the gradient energy coefficient changes from bulk to surface, has been establishing the new equation that helped us to extract the correlation between gradient energy coefficient and different parameters. The gradient energy coefficient has been related with hole fractions, temperature and density. The relationships between the above-mentioned parameters are then drawn according to our model. Both Simha-Somcynsky (SS) and Cahn-Hilliard (CH) models are employed together to calculate the thermodynamic properties of cyclohexane, namely, the hole fraction in temperature range at 313-473 K various presures up to 150 Mpa. Our values for the average and maximum percentage deviation of the specific volume of cyclohexane are calculated as 0.0196% and 0.0678% respectively
The external degree of freedom of linear and branched molecules of polymers played an important role in new polymer synthesis. The theory Simha-Somcynsky (SS) which established for the first time the statistical thermodynamics and polymers state of equation, using the mean field theory )that does not depend on the structural of materials). Expressed through the zeroth-order mean field theory through the hole vaccume cells as a measure of irregularity in the lattice. The (SS) theory has achieved quantitative success in statistical thermodynamics of polymers. The SS theory has been applied to extract the external degrees of freedom for polyethylene at different molecular weights. The external degree of freedom is very important parameter to specify the thermodynaics characteristic parameters. Applying SS hole theory, the thermodynamic properties of polyethylene was studied for temperature from 353K up to 473 and pressure from o.1Mpa up to150 Mpa. The minimum and maximum deviations in specific volume was found to be 0.045 (PE2100) and 1.138 (PE156) respectively..
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