Search

In order to further define the potential use of FTIR-ATR spectroscopy, as a non-destructive and reliable technique, for the analysis of the characteristics of post stamps, certified originals of the Principality of Serbia stamps (?Prince Michael issues?) issued in 1866 and 1868 as well as their forgeries were analyzed. Spectra enabling the comparison of the paper, dye and glue of stamps of so-called ?Vienna issues?, having denominations of 10 (orange-yellow), 20 (pink) and 40 para (blue) and ?Belgrade issues? (1 para-green and 2 para-reddish brown), as well as 24 expert-certified forgeries, were taken. It was shown that the applied technology was, in most of the cases, a fast and suitable technique for establishing clear differences between the spectral characteristics of the paper and dye used for the original stamps, and forgeries that were most probably made decades after the printing of the genuine stamps. The differences between printings of the same issues of the genuine stamps were also elaborated. It is proposed, for the first time in philatelic history, the possibility that ?Vienna issues? stamps may have been printed on two different papers, and, having in mind the technology of printing in the 19th century, potentially, not even at the same time or in the same printing house.

This article described the synthesis and characterization of new copolymer hydrogels containing two hydrophilic units-methacrylic acid (MAA) and 2-Acrylamido-2-methylpropane sulfonic acid (AMPS). The resulting hydrogels were characterized by various techniques: FTIR, Elemental analysis, SEM, Dynamic Molecular simulation, Dynamic-Mechanical analysis and DSC in order to confirm the structure of hydrogels and to predict the best ratio composition with enhanced physical chemical properties. The swelling behavior in water was studied as a function of ratio of monomers and their concentration in medium. An increase in AMPS content led to expansion of network and increase in swelling degree capacity in water. An increase in AMPS content did not significantly influence the glass transition temperature of copolymers, indicated that the physical properties of initial components were preserved. The equal amount of monomers contributed to the highest strength of hydrogels. Meanwhile, the introduction of AMPS to the system was an effective method for improving the performances of the poly(methacrylic acid)- based hydrogels. (C) 2016 Elsevier B.V. All rights reserved.

The aim of this work was to investigate the influence of specific anions on the cross-linking process of highly methoxylated pectin using the following copper salts CuSO4; Cu(C2H3O2)(2); CuCl2; and Cu(NO3)(2) wherein the initial salt concentrations were varied from 0.5 up to 10 g l(-1). It was found that the anions affected the sorption capacity wherein the Cu2+ sorption capacity from the sulphate solution was the highest, while it decreased in the presence of CH3COO-, Cl- and NO3- ions, respectively. This difference was mostly pronounced at the higher initial salt concentrations (co(Cu2+) gt 2 g l(-1)). The obtained beads were characterized by FTIR, MS, SEM/EDS microanalysis and mechanical compression tests up to 80% of deformation. The sorption data were applied to the Langmuir and Freundlich isotherm models and various calculated parameters confirmed the sulphate anion supportive nature in metal ion binding. The value of the K-f parameter for the cross-linking process of pectin in the presence of acetate, chloride and nitrate was approximately the same (K-f approximate to 0.027 g g(-1)), while it was higher in the presence of sulphate anions by more than 20% (K-f = 0.0352 g g(-1)). The predicted 1/n values (1/n lt 1, 1/n gt 1, 1/n = 1 for the sulphate, nitrate and acetate, and chloride anions, respectively) were the quantitative confirmation of the specific interactions involved in the cross-linking mechanism caused by different anions. The established anion influence was in accordance with the typical ion-specific influence on macromolecules in aqueous systems proposed by Hofmeister.

The aim of this study was the development of novel polysaccharide based films intended to be used as edible food packaging material. The films were prepared by solution casting method using highly methoxylated pectin (PEC) and poly(ethylene glycol) (PEG) of various molecular weights (400, 600 and 1000 gmol(-1)) in different ratios (5:1, 3:1 and 1:1). The film formation was supported by hydrogen bonding between PEC and PEG, which was evidenced by means of ATR-FTIR and NMR analysis. TGA revealed that generally PEG behaves like a pro-degrading agent for pectin, except in the case of PEC/PEG film with a ratio of 1:1. Furthermore, DSC thermograms indicated that PEG1000 exists as a separate phase in the pectin matrix while the formulations with PEG400 and PEG600 showed mainly amorphous morphology. The addition of PEG enhanced the plasticization of PEC films, as evidenced by progressive decreasing of the glass transition temperature values (T-g). The tensile test measurements showed that increasing concentration of PEG produced weaker and more flexibile films. Due to the increased molecular mobility, the pectin phase became more permeable to water vapor as the PEG concentration increased. The obtained results showed that the combination of both polymers resulted in interesting bio -inspired edible films with the potential to compete with commercially used synthetic package materials. This is the peer-reviewed version of the article: Šešlija, S., Nešić, A., Ružić, J., Kalagasidis Krušić, M., Veličković, S. J., Avolio, R., Santagata, G.,& Malinconico, M. (2018). Edible blend films of pectin and poly(ethylene glycol): Preparation and physico-chemical evaluation. Food HydrocolloidsElsevier Sci Ltd, Oxford., 77, 494-501. [https://doi.org/10.1016/j.foodhyd.2017.10.027] The published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/2473]

The aim of this paper is to present image analysis as a useful technique for fast, reliable and non-destructive detection of dimensional and structural changes in polymers. The possibility of applying image analysis was demonstrated in the case of solvent-induced crystallization of poly(ethylene terephthalate) (PET) containers filled with commonly used organic solvents: chlorobenzene, isophorone, xylene, Espesol, Shellsol A 100, Solvesso 150, propylene glycol, glycerin and water and subjected to the storage stability test at 54 ?C for 14 days (CIPAC 1-MT 46.1.3). In addition, the obtained results were analyzed using one-step analysis of variance (ANOVA) combined with the Duncan?s statistical test (p

Films of chitosan and poly(itaconic acid) in various different ratios have been prepared by membrane casting. The enhancement in the proton conductivity and uptake of water was observed as the content of poly(itaconic acid) in film increased. The proton conductivity of chitosan/poly(itaconic) films was comparative with commercially used synthetic sensor Nafion 117. Films showed thermal stability up to 185 degrees C. The proposed experiment might open up a new possibility for use of chitosan/poly(itaconic acid) films as a biosensors due to their advantages: low cost, simple preparation and good conductive sensitivity. (C) 2015 Elsevier B.V. All rights reserved.

In this work, the reliability of image analysis for the numerical evaluation of Basic Red 46 (BR 46) dye adsorption process was studied. The image analysis was carried out on dye adsorbed onto SBA-15 mesoporous silica, by use of Image-Pro Plus software. Pixel-specific calibration curves were derived and used to obtain dye concentration from the three different primary color channels (red, green, and blue) recorded at each pixel. In order to establish credibility of this method for quantification of adsorption processes, these data were compared with dye adsorption parameters obtained by UV-vis analysis. Among the three different primary color channels, the best results were obtained when the blue color channel was applied. In this case, the average relative error was 0.86%. The obtained results showed that a dye adsorbed on SBA-15 can be determined with the use of Image-Pro Plus with the same sensitivity as with the use of spectrophotometric analysis for the determination of changes in dye concentration during the adsorption process.

Mimicking the extraordinary performances of natural materials presents an attractive, but challenging approach in the synthesis of advanced functional materials. In the field of separation techniques, the design of a low-cost, regenerative, environmentally friendly sorbent and the utilization of most of its active centers to remove the targeted pollutant are everyday challenges. The combination of casein and poly(sodium methacrylate) (PMANa) in the form of a soft polymer network is proposed as a promising sorbent for the removal of Ni2+ from wastewater. Such a combination and an applied synthetic route form hybrid materials with better sorption properties than both their components alone. SEM and TEM show that caseinate micelles are dissociated and the more exposed protein structure is stabilized by the PMANa network and able to form various stable complexes. The achieved sorption capacity (224 mg g(-1)) is among the highest reported in the literature. The very high removal efficiency in the wide range of the initial Ni2+ concentrations (0.05-200 ppm) and easy and complete regeneration without decrease in sorption capacities make these low-cost materials highly sensitive sorbents attractive for use under real conditions where it is necessary to avoid environmental risks and provide the recovery and reuse of the metal.