Showing papers on "Differential scanning calorimetry published in 2010"
TL;DR: In this article, the chemical properties of poly(lactic acid) were analyzed in order to analyze the variation of its chemical structure, thermal degradation and mechanical properties, and the results were qualitatively corroborated by FTIR.
582 citations
TL;DR: The DSC screening method and classification scheme may be a useful tool to quickly assess the glass forming ability (GFA) and potential GS of new chemical entities during early drug development.
545 citations
TL;DR: In this article, the effects of CMC content on blend structure, thermal stability, water solubility and water sorption, and mechanical properties were systematically investigated, and the results indicated that the structure and properties of soy protein isolate (SPI) were modified and improved by blending with CMC.
527 citations
Journal Article•
TL;DR: This paper reviews the best-known differential scanning calorimetries (DSCs), and describes here the most extensive applications of DSC in biology and nanoscience.
Abstract: This paper reviews the best-known differential scanning calorimetries (DSCs), such as conventional DSC, microelectromechanical systems-DSC, infrared-heated DSC, modulated-temperature DSC, gas flow-modulated DSC, parallel-nano DSC, pressure perturbation calorimetry, self-reference DSC, and high-performance DSC. Also, we describe here the most extensive applications of DSC in biology and nanoscience.
360 citations
TL;DR: In this paper, a facile microwave-solvothermal synthesis of nanostructured Li2MSiO4/C and Li2MnSiO4 cathodes has been used to improve crystallinity and enhance electronic conductivity.
Abstract: Nanostructured Li2FeSiO4 and Li2MnSiO4 cathodes have been synthesized by a facile microwave-solvothermal synthesis. To improve crystallinity and enhance electronic conductivity, the resulting samples have been mixed with sucrose and heated at 650 °C for 6 h in argon atmosphere. The Li2MSiO4/C nanocomposites, thus, obtained have been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, electrochemical measurements, and differential scanning calorimetry. The Li2FeSiO4/C sample exhibits good rate capability and stable cycle life, with discharge capacities of 148 mAh/g at room temperature and 204 mAh/g at 55 °C. Although Li2MnSiO4/C shows higher discharge capacities of 210 mAh/g at room temperature and 250 mAh/g at 55 °C, it suffers from poor rate capability and drastic capacity fade. The disparity in the electrochemical performance and redox behavior between Li2FeSiO4/C and Li2MnSiO4/C can be attributed to the differences in the structural st...
341 citations
TL;DR: In this paper, layer-aligned poly(vinyl alcohol)/graphene nanocomposites in the form of films are prepared by reducing graphite oxide in the polymer matrix in a simple solution processing.
336 citations
TL;DR: In this paper, an expanded graphite (EG)/paraffin composite phase change materials (PCMs) with mass fraction of EG varying from 0 to 10% were prepared and characterized.
314 citations
TL;DR: In this article, a microencapsulated paraffin composites with SiO2 shell as thermal energy storage materials were prepared using sol-gel methods using Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD) and scanning electronic microscope (SEM).
261 citations
TL;DR: In this article, Nitrogen doped anatase-rutile heterojunctions are successfully synthesized through an ethylenediaminetetraacetic acid (EDTA) modified sol−gel process.
Abstract: Nitrogen doped anatase-rutile heterojunctions are successfully synthesized through an ethylenediaminetetraacetic acid (EDTA) modified sol−gel process An FT-IR study of EDTA modified TiO2 gel confirms the existence of an ionic intermediate (as indicated by a Δν value of 233 cm−1) Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Raman spectroscopy are employed to study the phase evolution, phase purity, and crystallite size of samples Formations of O−Ti−N and N−Ti−N bonds in calcined samples are confirmed using XPS and FT-IR spectroscopy All EDTA modified samples show significantly higher visible light photocatalytic activity than the unmodified sample The most active nitrogen doped heterojunction obtained at 400 °C exhibits 9-fold visible light activity in comparison to the standard photocatalyst Degussa P-25 It is proposed that the photo excited electrons (from the visible midgap level) are effectively transferred from the conduction band of anatase to that of rutile causing eff
256 citations
TL;DR: In this article, a shape memory polymer based on polyvinyl alcohol (SM-PVA) chemically cross-linked with glutaraldehyde exhibits good temperature responsive shape memory behavior, which is observed by immersing this kind of SM-pVA in good or poor solvents (including water, DMF, and EG etc.).
Abstract: A shape memory polymer based on poly(vinyl alcohol) (SM-PVA) chemically cross-linked with glutaraldehyde exhibits good temperature responsive shape memory behavior. In the present investigation, solvent-induced shape memory behavior is observed by immersing this kind of SM-PVA in good or poor solvents (including water, DMF, and EG etc.) for PVA. A significant indication of shape memory is the decrease of the glass transition temperature (Tg), which is caused by PVA swelling in certain solvents. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), swelling equilibrium and bending tests are carried out to find the mechanism behind this interesting phenomenon. Factors that influence the permeation of solvents in the polymer depend on the rate and degree of swelling and whether swelling will occur, which determines the shape recovery ratio in different solvents. Water can induce shape recovery in a shorter time than organic solvents. The structure of water and PVA, and the interaction between them, contribute to the shorter recovery time. SM-PVA has an excellent shape recovery ratio even after several test cycles. Using solvents as a stimulus for shape memory behavior will extend applications of SMPs, especially in the field of medical devices, where stimulus instead of heat is highly desired.
237 citations
TL;DR: In order to reduce pollution caused by traditional non-biodegradable plastic films, renewable raw materials from plants and wastes of meat industries have been employed inThis work, a hydrolysable chestnut-tree tannin was used for gelatin modification.
TL;DR: In this paper, the authors focused on the preparation and characterization of fatty acid eutectic/polymethyl methacrylate (PMMA) form-stable phase change material (PCM).
TL;DR: A series of 0−3 metal oxide−polyolefin nanocomposites are synthesized via in situ olefin polymerization, using the following single-site metallocene catalysts: C2-symmetric dichloro[rac-ethylenebisindenyl]zirconium(IV), Me2Si(tBuN), and (η5-C5Me4)TiCl2, and
Abstract: A series of 0−3 metal oxide−polyolefin nanocomposites are synthesized via in situ olefin polymerization, using the following single-site metallocene catalysts: C2-symmetric dichloro[rac-ethylenebisindenyl]zirconium(IV), Me2Si(tBuN)(η5-C5Me4)TiCl2, and (η5-C5Me5)TiCl3 immobilized on methylaluminoxane (MAO)-treated BaTiO3, ZrO2, 3-mol %-yttria-stabilized zirconia, 8-mol %-yttria-stabilized zirconia, sphere-shaped TiO2 nanoparticles, and rod-shaped TiO2 nanoparticles. The resulting composite materials are structurally characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), 13C nuclear magnetic resonance (NMR) spectroscopy, and differential scanning calorimetry (DSC). TEM analysis shows that the nanoparticles are well-dispersed in the polymer matrix, with each individual nanoparticle surrounded by polymer. Electrical measurements reveal that most of these nanocomposites have leakage current densities of ∼10−6−10−8 A/cm2; relative permittivities in...
TL;DR: In this paper, the authors showed that the outstanding toughness and aging resistance of the 4 component alloy, i.e., PLA/PC/SEBS/EGMA = 40/40/5/5 (wt. ratio), seems to come from the negative pressure effect of SEBS that dilates the plastic matrix consisting of PLA and polycarbonate to enhance the local segment motions.
TL;DR: In this paper, cellulose whiskers and microfibrillated cellulose (MFC) were used as reinforcing phase to prepare nanocomposite films using latex of natural rubber as matrix.
TL;DR: In this paper, the crystal phase identification for polyvinylidene fluoride (PVDF) nanocomposites is discussed and clarified, based on X-ray scattering, vibrational spectra, and thermal analysis.
TL;DR: In this article, structural, optical, thermal and morphological studies were performed for pure PVA/PVP (50/50) blend and PVA-PVP blend filled with different concentrations of chitosan upto 40% using casting method.
Abstract: Structural, optical, thermal and morphological studies were performed for pure PVA/PVP (50/50) blend and PVA/PVP blend filled with different concentrations of chitosan upto 40 wt% using casting method. The prepared films were investigated by different techniques. All techniques demonstrate the complexation between chitosan and the polymers blend. There were some changes in the IR absorption bands position and its intensities. UV–vis analysis revealed intensity of the shoulder around 273–280 nm increase with increasing chitosan content. Differential scanning calorimetry (DSC) showed thermal stability of the product samples and that has improved after filling chitosan increases. Scanning electron microscope (SEM) images of different concentrations of films revealed that large crystals characteristic of chitosan were also frequently present, when chitosan content increase upto 20 wt%, rough surfaces and crystalline structures are the dominant features. The X-ray diffraction (XRD) showed that the incorporation of chitosan into the polymeric matrix causes decreasing in the crystallinity degree of the samples and this indicates the complexation between the filler and the polymers blend. Thermogravimetric analysis (TGA) is used to study the samples in the temperature range of 30–500 °C. Figures show typical TGA thermograms of weight loss as a function of temperature for the present system.
TL;DR: In this article, broadband dielectric spectroscopy (BDS) was used to investigate the intercalated water in graphite oxide (GO) by using different techniques, such as differential scanning calorimetry, X-ray diffraction, and attenuated total reflection geometry in FTIR.
Abstract: Intercalated water in graphite oxide (GO) was investigated by using different techniques: broadband dielectric spectroscopy (BDS) (10−2−109 Hz; 140−300 K), differential scanning calorimetry, X-ray diffraction, and attenuated total reflection geometry in Fourier transform infrared spectroscopy (ATR-FTIR). We have studied the water concentration (cw) region from 0 wt % (anhydrous GO) up to 25 wt % since in this range the water crystallization is avoidable. The interlayer distance during hydration increases from 5.67 to 8 A which corresponds to the uptake of a water monolayer in the interlayer space of GO. A clear relaxation due to water molecule reorientation is seen by BDS. The rotational water dynamics is dependent on the hydration level. At high water concentration (cw > 15 wt %), water−water interactions seem to dominate the dielectric response. This result is also compatible with those from FTIR and X-ray measurements. In this water concentration region, a slight dynamical crossover in the temperature ...
TL;DR: The new annealing method yields more accurate data than the previous scanning method when solubility equilibrium is slow to achieve, and in practice, these two methods can be combined for efficiency.
TL;DR: In this paper, the thermal conductivity of shape-stabilized paraffin/high density polyethylene (HDPE) composite phase change material (PCM) was improved by addition of graphite powder (GP) and expanded graphite (EG).
TL;DR: In this article, phase change materials (Rubitherm® RT 27) microcapsules were successfully obtained by two different methods using two different coacervates (Sterilized Gelatine/Arabic Gum for SG/AG method and Agar-Agar/Agar Arabic Gum for AA/AG) and thermal stability determination was carried out by Thermogravimetric analyses (TG).
TL;DR: In this article, the authors combine dielectric spectroscopy, X-ray reflectometry, alternating current and differential scanning calorimetry (DSC) to study glassy dynamics and the glass transition in nanometric thin layers of polystyrene (PS) having widely varying molecular weights.
Abstract: Broadband dielectric spectroscopy (BDS), spectroscopic vis-ellipsometry (SE), X-ray reflectometry (XRR), and alternating current (ACC) as well as differential scanning calorimetry (DSC) are combined to study glassy dynamics and the glass transition in nanometric thin (≥5 nm) layers of polystyrene (PS) having widely varying molecular weights (27 500−8 090 000 g/mol). For the dielectric measurements two sample geometries are employed, the common technique using evaporated electrodes and a recently developed approach taking advantage of nanostructures as spacers. All applied methods deliver the concurring result that deviations from glassy dynamics and from the glass transition of the bulk do not exceed margins of ±3 K independent of the layer thickness and the molecular weight of the polymer under study. Our findings are discussed in the context of the highly controversial literature and prove that an appropriate sample preparation is of paramount importance.
TL;DR: The elevated aggregation levels induced by salt, low pH, and high protein concentrations could be successfully predicted by this thermal stability screening and could be widely applied in the biopharmaceutical industry for formulation and process development, and characterization.
TL;DR: This study shows that incorporation of polyethylene glycol (PEG) into nanochannels of porous coordination polymers (PCPs) enabled observation of thermal transitions of the chain assemblies by differential scanning calorimetry.
Abstract: The thermal transitions of confined polymers are important for the application of polymers in molecular scale devices and advanced nanotechnology. However, thermal transitions of ultrathin polymer assemblies confined in subnanometre spaces are poorly understood. In this study, we show that incorporation of polyethylene glycol (PEG) into nanochannels of porous coordination polymers (PCPs) enabled observation of thermal transitions of the chain assemblies by differential scanning calorimetry. The pore size and surface functionality of PCPs can be tailored to study the transition behaviour of confined polymers. The transition temperature of PEG in PCPs was determined by manipulating the pore size and the pore-polymer interactions. It is also striking that the transition temperature of the confined PEG decreased as the molecular weight of PEG increased.
TL;DR: In this article, the microencapsulation of phase change materials (PCMs) by a suspension copolymerization of styrene (St) and methyl methacrylate (MMA) has been studied.
TL;DR: A comparison of the adsorption of water, methanol, and ethanol polar vapors by the flexible porous chromium(III) terephthalate MIL-53(Cr) was investigated by complementary techniques including adsorptive gravimetry, ex situ X-ray powder diffraction, microcalorimetric, thermal analysis, IR spectroscopy, and molecular modeling.
Abstract: A comparison of the adsorption of water, methanol, and ethanol polar vapors by the flexible porous chromium(III) terephthalate MIL-53(Cr) was investigated by complementary techniques including adsorption gravimetry, ex situ X-ray powder diffraction, microcalorimetry, thermal analysis, IR spectroscopy, and molecular modeling. The breathing steps observed during adsorption strongly depend on the nature of the vapor. With water, a significant contraction of the framework is observed. For the alcohols, the initial contraction is followed by an expansion of the framework. A combination of IR analysis, X-ray diffraction, and computer modeling leads to the molecular localization of the guest molecules and to the identification of the specific guest−guest and host−guest interactions. The enthalpies of adsorption, measured by microcalorimetry, show that the strength of the interactions decreases from ethanol to water. Differential scanning calorimetry experiments on an EtOH/H2O mixture suggest a selective adsorpti...
TL;DR: Graphene sheets were produced from graphite oxide using a simple two-step process as mentioned in this paper, in which the mix is heated in an inert gas environment (e.g. N2) for a very short time to a moderate temperature (ca. 600°C). Reaction temperature selection should be consistent with the decomposition temperature of the expansion-reduction agent.
TL;DR: In this paper, a facile oxidative polymerization approach using p-toluene sulfonic acid as a dopant and ammonium persulfate as an oxidant was used to construct conductive polypyrrole/SiC nanocomposites.
Abstract: Conductive polypyrrole/SiC nanocomposites are fabricated via a facile oxidative polymerization approach using p-toluene sulfonic acid as a dopant and ammonium persulfate as an oxidant. The effects of the nanoparticle loading, ratio of oxidant to monomers, and nanoparticle morphology (spheres and rods) on the physicochemical properties are investigated. Various characterization methods are carried out to determine the material properties. Thermal gravimetric analysis demonstrates an improved thermal stability of polypyrrole in the polymer nanocomposites (PNCs) with a higher decomposition temperature. The glass-transition temperature and melting temperature of the polymer and its nanocomposites are determined by differential scanning calorimetry with a decreased melting temperature of polypyrrole in the PNCs. The microstructures of pure polypyrrole and PNCs are observed by scanning electron microscopy. Powder X-ray diffraction analysis demonstrates the crytallinity of polypyrrole, and poor crystallinity is ...
TL;DR: In this paper, a differential fast scanning nano-calorimeter utilizing a new power compensation scheme is described. But the authors focus on determination of specific heat capacity out of the measured data.
TL;DR: It appears that felodipine-PVP solid dispersions are susceptible to moisture-induced immiscibility when stored at a relative humidity >or=75%.