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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Synthesis and characterization of TiO2 co-polymeric hydrogel
摘要： In this study, TiO2 doped acrylic acid-co-vinyl pyrrolidone (AA-co-VP) composite co-polymeric hydrogel was synthesized by free radical polymerization technique. Titanium dioxide (TiO2) were chosen because of its superior properties such as high activity, chemical stability, low cost, non-toxicity, and stability during irradiation. TiO2 doping were carried out by varying mass ratios as 0.05%, 0.5% and 1%. Conversion, cross-linking and swelling values of each hydrogel were calculated. According to swelling behavior, while TiO2 dope ratio increase, swelling value was also increased. Chemical, morphological and thermal properties of hydrogels were specified by using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDX), mapping and thermogravimetric analysis (TGA-DSC) techniques. TiO2 doping provides superior properties to co-polymeric hydrogel. Hydrogels have also characteristic properties of both acrylic acid and vinyl pyrrolidone.
关键词： SEM-EDX,hydrogel,TGA-DSC,free radical polymerization,acrylic acid-co-vinyl pyrrolidone,FTIR,TiO2,swelling behavior
更新于2025-09-09 09:28:46
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Photocured characteristics of fast photocurable acrylic formulations and investigations by differential photo calorimeter
摘要： Bisphenol-A glycerolate diacrylate has been synthesized, characterized and formulated with acrylate monomers. Photocrosslinking characteristics of UV-curable acrylate monomers were investigated with the help of differential photocalorimeter equipped with UV radiometer using UV radiation of 365 nm at an intensity of 10 mWcm-2. The heat of photoreaction, curing rate and degree of conversion were studied using theoretical kinetic equations to investigate the effect of 2-ethylhexyl acrylate on photocuring behaviour of bisphenol-A glycerolate diacrylate, acrylic acid and methyl methacrylate. Curing rate reached its maximum value within 7.5 s, and more than 70% monomers were photopolymerized in all the formulations. Enthalpy of photopolymerization was found in the range of - 206 to - 171 J g-1, and maximum degree of conversion attained was 82–84% within a time span of 25 s. A comparison of DPC curves reveals that 2-ethyl hexyl acrylate has no significant effect on the curing rate of photopolymerization, however, a small decrease in degree of conversion was observed. Further, FTIR quantification of C=C bond conversion was performed in order to estimate the degree of conversion after 25 s. Specific gravity and mechanical properties of the casted films have also been reported. Glass transition temperatures were also recorded with the help of DSC, and a remarkable shift from 40.52 to 23.48 °C was observed imparting flexibility to the UV-cured compositions. The developed photocurable acrylic formulations have been used for preparation of laminated glasses which were analysed for fracture and adhesion test.
关键词： 2-Ethyl hexyl acrylate,Photopolymerization,DSC,UV curing,Glass transition,Laminated glass
更新于2025-09-09 09:28:46
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Study of Polymorphism of Borovanadate Glass of Sodium by Raman Spectroscopy Low Frequencies
摘要： Sodium tetraborate (100 – x)(Na2B4O7.10H2O) – xV2O5, (x = 0 to 20 mole %) has been elaborated by splat cooling technique. Raman Measurements on the doped and non polish samples reveal the presence of the of α-NaVO3 crystal on the superficial layer. After polishing, Raman spectra characteristic of glasses are obtained with two main bands located at 555 and 1097 cm-1 in the undoped glass and four bands at 241, 381, 776 and 938 cm-1 for the vanadium oxyde doped glasses. The volume devitrification of these glasses occurs at 750° C and the β-NaVO3 crystalline phase is identified by Raman scattering.
关键词： Non-linear optics,Oxide glasses,XRD,Raman scattering,DSC
更新于2025-09-09 09:28:46
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Molecular structure of PANI and its homologue PANI–PEO2000 catalyzed by Maghnite-H+ (Algerian MMT): synthesis, characterization and physical and chemical properties
摘要： The homopolymer (PANI) and its homologue PANI–PEO2000 copolymer have been prepared under effect of Maghnite-H+ (Algerian MMT) in different weight percentages (wt%) by cationic polymerization method. The formation of the hydrogen bonding between PANI and PEO2000 and structure of PANI are predicted by the FT-IR and 1HNMR spectra. Glass transition temperature of pure PANI and pure PEO2000 are, respectively, Tg = 74 °C and Tg = 65 °C, but DSC analysis for the copolymer (PANI–PEO2000) showed only one (Tg = 16.79 °C) implying compatibility of PANI and PEO2000. Here we can suggest that under suitable condition (the amount of catalyst, molecular weight and functionality of the reactive stabilizer (PEO2000) and molar ratio of (PANI/PEO2000), our catalyst can improve the morphology, structure and chemical properties of PANI and its homologue PANI–PEO2000.
关键词： Maghnite-H+,1HNMR spectroscopy,DSC,PEO,GPC,Conducting polymer,Green catalyst,Polyaniline
更新于2025-09-09 09:28:46
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Correlation between the structure and structural relaxation data for (GeSe2)y(Sb2Se3)1-y glasses
摘要： Combined calorimetric and structural study, employing the techniques of differential scanning calorimetry and Raman spectroscopy, was performed to describe the enthalpy relaxation processes in the (GeSe2)y(Sb2Se3)1-y chalcogenide glasses. The full glass forming compositional region (y = 0.3–0.9) was explored. The enthalpy relaxation was described in terms of the phenomenological Tool-Narayanaswamy-Moynihan model. Compositional evolution of the glass transition temperatures and relaxation activation energies was explained based on the changing average bond energies and overall interconnectivity of the glassy matrices. Resemblance between the activation energies of the relaxation processes and viscous flow was confirmed for all studied glasses. Non-linearity and non-exponentiality of the enthalpy relaxation were found to be invariant with composition. The structural relaxation kinetics as well as kinetic fragilities determined for the present (GeSe2)y(Sb2Se3)1-y glassy system were very similar to the results obtained earlier for the (GeS2)y(Sb2S3)1-y glasses, which can be attributed to the similarly constrained topology of the pseudo-binary compositional lines.
关键词： Enthalpy relaxation,Raman spectroscopy,TNM model,Ge-Sb-Se glasses,DSC
更新于2025-09-04 15:30:14
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Differential Scanning Calorimetry and Infrared Spectroscopy Combined with Chemometric Analysis to the Determination of Coffee Adulteration by Corn
摘要： Roasted and ground coffee is targeted by fraudulent addiction of products. In this way the determination of contaminants in coffee has economic and nutritional importance. In this study, the coffee adulteration by corn were detected using DSC (differential scanning calorimetry) and FTIR (Fourier transform infrared spectroscopy) coupled to PCA (principal component analysis), and PLS (partial least squares) models. Three different levels of roasted and ground Coffea arabica L. were used to prepare mixtures with roasted and ground corn. The level of adulteration used was between 0.5 to 40% (m/m). It was observed that both DSC and FTIR coupled with PCA are able to discriminate adulterated from unadulterated samples of coffee by corn at levels below 1%. PLS models were built with DSC and FTIR data reaching good correlation between the values of estimated and reference concentrations, with RMSECV (root mean square error of cross-validation) lower than 3.5% for DSC data and 2.7% for FTIR data.
关键词： adulteration,ATR-FTIR,chemometric analysis,DSC,coffee
更新于2025-09-04 15:30:14
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Designing Conjugated Polymers for Molecular Doping: The Roles of Crystallinity, Swelling, and Conductivity in Sequentially-Doped Selenophene-Based Copolymers
摘要： Although chemical doping is widely used to tune the optical and electrical properties of semiconducting polymers, it is not clear how the degree of doping and the electrical properties of the doped materials vary with the bandgap, valence band level, and crystallinity of the polymer. We address this question utilizing a series of statistical copolymers of poly(3-hexylthiophene) (P3HT) and poly(3-heptylselenophene) (P37S) with controlled gradients in bandgap, valence band position and variable crystallinity. We dope the copolymers in our series with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) using solution sequential processing (SqP). We then examine the structures of the films using grazing incidence wide-angle x-ray scattering (GIWAXS), differential scanning calorimetry (DSC) and ellipsometric porosimetry, and the electrical properties of the films via the AC Hall effect. We find that the ability of a particular copolymer to be doped is largely determined by the offset of the polymer’s valence band energy level relative to the LUMO of F4TCNQ. The ability of the carriers created by doping to be highly mobile and thus contribute to the electrical conductivity, however, is controlled by how well the polymer can incorporate the dopant into its crystalline structure, which is in turn influenced by how well it can be swelled by the solvent used for dopant incorporation. The interplay of these effects varies in a non-monotonic way across our thiophene:selenophene copolymer series. The position and shape of the polaron absorption spectrum correlate well with the polymer crystallinity and carrier mobility, but the polaron absorption amplitude does not reflect the number of mobile carriers, precluding the use of optical spectroscopy to accurately estimate the mobile carrier concentration. Overall, we find that the degree of crystallinity of the doped films is what best correlates with conductivity, suggesting that only carriers in crystalline regions of the film, where the dopant counterions and polarons are forced apart by molecular packing constraints, produce highly mobile carriers. With this understanding, we are able to achieve conductivities in this class of materials exceeding 20 S/cm.
关键词： semiconducting polymers,conductivity,ellipsometric porosimetry,GIWAXS,solution sequential processing,valence band level,F4TCNQ,poly(3-heptylselenophene),AC Hall effect,poly(3-hexylthiophene),DSC,bandgap,chemical doping,crystallinity
更新于2025-09-04 15:30:14