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Showing papers on "Differential scanning calorimetry published in 2014"


Journal ArticleDOI
Jian Kang1, Jiayao Zhang1, Zhengfang Chen1, Feng Yang1, Jinyao Chen1, Ya Cao1, Ming Xiang1 
TL;DR: In this article, the authors investigated the impact of isothermal treatment on the polymorphic behavior and the isothermal crystallization kinetics of a β-iPP sample with different melt structures by differential scanning calorimetry.
Abstract: A previous work reported that the polymorphic crystallization behavior of isotactic polypropylene (iPP) can be efficiently tuned by the combination of controlling the melt structure (i.e., creation of an ordered structure by tuning the fusion temperature Tf by self-nucleation) and the addition of the α-/β-dual-selective nucleation agent (dual-selective β-NA, tradename WBG-II). In this study, we further investigated the impact of isothermal treatment on the polymorphic behavior and the isothermal crystallization kinetics of a β-iPP sample with different melt structures by differential scanning calorimetry (DSC). The results of isothermal crystallization kinetics study illustrated that as Tf decreased gradually from Region I to Region II and Region III, two sharp increases of the crystallization rate took place at the transition temperatures of Region II, showing that the enhancement of β-phase crystallization took place in a certain crystallization rate window. The calculation of the Avrami exponent n revealed that the two-dimensional growth of crystallites with instantaneous nucleation took place before and after the occurrence of the synergetic effect between the ordered structures and the dual-selective β-NA (when Tf ≥ 168 °C). Moreover, it was found that the occurrence of the synergetic effect in the fusion temperature range of Region II can evidently enhance the βc of the sample: by tuning the fusion temperature Tf and the isothermal crystallization temperature Tc, the relative percentage of β-phase (βc) of the single β-iPP sample with only 0.03 wt.% β-NA can be efficiently tuned in the wide βc range of 0 %–95.0 %; meanwhile, the sensitivity of βc to the isothermal crystallization temperature Tc was reduced.

330 citations


Journal ArticleDOI
TL;DR: In this article, the static and dynamic properties of poly(2-vinylpyridine)/silica nanocomposites are investigated by temperature modulated differential scanning calorimetry, broadband dielectric spectroscopy (BDS), small-angle X-ray scattering (SAXS), and transmission electron microscopy.
Abstract: The static and dynamic properties of poly(2-vinylpyridine)/silica nanocomposites are investigated by temperature modulated differential scanning calorimetry, broadband dielectric spectroscopy (BDS), small-angle X-ray scattering (SAXS), and transmission electron microscopy. Both BDS and SAXS detect the existence of an interfacial polymer layer on the surface of nanoparticles. The results show that whereas the calorimetric glass transition temperature varies only weakly with nanoparticle loading, the segmental mobility of the polymer interfacial layer is slower than the bulk polymer by 2 orders of magnitude. Detailed analysis of BDS and SAXS data reveal that the interfacial layer has a thickness of 4–6 nm irrespective of the nanoparticle concentration. These results demonstrate that in contrast to some recent articles on polymer nanocomposites, the interfacial polymer layer is by no means a “dead layer”. However, its existence might provide some explanation for controversies surrounding the dynamics of poly...

241 citations


Journal ArticleDOI
01 Mar 2014-Energy
TL;DR: In this article, the fabrication, physico-chemical characterizations and thermal properties of n-octadecane nanocapsules as organic PCM (phase change materials) for thermal energy storage were investigated.

193 citations


Journal ArticleDOI
TL;DR: In this paper, the latent heat thermal energy storage properties of micro/nano encapsulated paraffin eutectic mixtures (PEMs) with polymethylmethacrylate (PMMA) shell were investigated.

192 citations


Journal ArticleDOI
TL;DR: In this paper, an experimental investigation on a sodium ion conducting polymer blend electrolyte system based on polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP), complexed with NaBr salt is presented.

186 citations


Journal ArticleDOI
TL;DR: In this article, the authors reported large enhancement in specific heat capacity of a eutectic salt mixture on dispersing alumina nanoparticles at 1% mass concentration and with nominal diameter of ∼10nm.

185 citations


Journal ArticleDOI
TL;DR: In this article, the optimal concentration of alumina nanoparticles in doped molten Hitec that maximizes its specific heat capacity was investigated, and a simplified model of the interfacial area was developed to explain the optimal concentrations.

184 citations


Journal ArticleDOI
TL;DR: In this paper, a micro-encapsulated phase change material (PCM) was used for thermal energy storage applications, and the morphology and particle sizes of microcapsules were analyzed by scanning electron microscopy, (SEM).

179 citations


Journal ArticleDOI
01 Aug 2014-Energy
TL;DR: In this paper, a paraffin/diatomite/MWCNTs composite PCM was designed for further applications in producing thermal energy storage cement-based composites.

172 citations


Journal ArticleDOI
TL;DR: Based on theoretical calculation, myristic acid,palmitic acid-stearic acid ternary eutectic mixture (MA-PA-SA) with a mass ratio of MA:PA:SA = 52.2:29.4 was prepared firstly as mentioned in this paper.

167 citations


Journal ArticleDOI
15 Feb 2014-Fuel
TL;DR: In this article, a method for determining the kinetics of low temperature coal oxidation based on thermogravimetric analysis and differential scanning calorimetry (TGA-DSC) was developed.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the gas separation performance of neat and alloyed poly(Ether Block Amide) [PEBA] (grade 1657) membranes and showed that the alloyed membranes exhibit better separation performance compared with the neat PEBA membranes.

Journal ArticleDOI
TL;DR: It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon, which allows CSP plants to have energy availability and dispatchability using available industrial technologies.
Abstract: Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable. 65.: Thermal properties of condensed matter; 65.20.-w: Thermal properties of liquids; 65.20.Jk: Studies of thermodynamic properties of specific liquids

Journal ArticleDOI
05 Aug 2014-Polymer
TL;DR: In this article, the thermodynamic properties of poly(butylene 2,5-furan dicarboxylate) were studied using differential scanning calorimetry (DSC).

Journal ArticleDOI
TL;DR: In this paper, the effect of the addition of LiNO3 and/or Ca(NO3)2 to the solar salt NaNO3/KNO3, which is used as a storage material in CSP plants, on the physicochemical properties thereof was studied.

Journal ArticleDOI
TL;DR: In this article, the thermal properties and thermal stability of microencapsulated palmitic acid (PA) with titanium dioxide (TiO 2 ) shell as shape-stabilized thermal energy storage material was synthesized through a sol-gel process.

Journal ArticleDOI
TL;DR: Results showed that the water vapor permeability (WVP) and water solubility (WS) of the agar-based nanocomposite films significantly decreased about 13% and 21%, respectively, upon increasing the NCC content to 10%.

Journal ArticleDOI
TL;DR: In this paper, a LiNO3/KCl-expanded graphite (EG) composite phase change material (PCM) was prepared for solar thermal energy storage application at high temperature (∼200 °C).

Journal ArticleDOI
TL;DR: In this article, the application of different isomers of furandicarboxylic acid, or FDCA, obtained from agro-residues, in polyester synthesis is presented.

Journal ArticleDOI
TL;DR: In this paper, the thermal characteristics under oxidizing atmosphere of several species of microalgae: Nannochloropsis gaditana (NG), Scenedesmus almeriensis (SC), and Chlorella vulgaris (CV) were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) coupled with mass spectrometry (MS).

Journal ArticleDOI
TL;DR: In this paper, a dual-functional phase change material based on an n-eicosane core and Fe3O4/SiO2 hybrid shell was designed as a new type of dual functional phase change materials.

Journal ArticleDOI
TL;DR: In this article, double-walled shells of polystyrene/graphene oxide nanosheets were used to stabilize oil-in-water (O/W) Pickering emulsion templating.
Abstract: The microencapsulation of phase change materials (n-hexadecane) with double-walled shells (polystyrene/graphene oxide) was realized from Pickering emulsion templating. Graphene oxide nanosheets were modified by the polycondensate of diethanolamine and adipic acid, which can well stabilize oil-in-water (O/W) Pickering emulsions. The morphology of the double-walled shell of polymer microspheres was observed by scanning electron microscopy (SEM). The thermal and barrier properties of microcapsules were studied using differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and the flammability test. DSC results indicate that the encapsulation ratio of n-hexadecane is as high as 78%. The encapsulated phase change material has good thermal stability, owing to the existence of graphene oxide on the surface protecting the core material from leakage and evaporation. This double-walled microencapsulation of phase change materials may have potential applications in energy storage and energy saving.

Journal ArticleDOI
TL;DR: This work demonstrates the first example of an IL incorporated within the micropores of a MOF, and provides a novel strategy for stabilizing the liquid phase of the ILs down to a lower temperature region.
Abstract: Controlling the dynamics of ionic liquids (ILs) is a significant issue for widespread use. Metal–organic frameworks (MOFs) are ideal host materials for ILs because of their small micropores and tunable host–guest interactions. Herein, we demonstrate the first example of an IL incorporated within the micropores of a MOF. The system studied consisted of EMI-TFSA (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide) and ZIF-8 (composed of Zn(MeIM)2; H(MeIM)=2-methylimidazole) as the IL and MOF, respectively. Construction of the EMI-TFSA in ZIF-8 was confirmed by X-ray powder diffraction, nitrogen gas adsorption, and infrared absorption spectroscopy. Differential scanning calorimetry and solid-state NMR measurements showed that the EMI-TFSA inside the micropores demonstrated no freezing transition down to 123 K, whereas bulk EMI-TFSA froze at 231 K. Such anomalous phase behavior originates from the nanosize effect of the MOF on the IL. This result provides a novel strategy for stabilizing the liquid phase of the ILs down to a lower temperature region.

Journal ArticleDOI
TL;DR: In this article, a new class of benzoxazine-containing monomers has been prepared from renewable resource (eugenol, a natural phenol obtained from clove oil), paraformaldehyde and various aromatic diamines.
Abstract: Polybenzoxazines are phenolic-like materials that possess dimensional and thermal stability, and they release no by-products during their polymerization. In this study, a new class of benzoxazine-containing monomers has been prepared from renewable resource (eugenol, a natural phenol obtained from clove oil), paraformaldehyde and various aromatic diamines. The structures of the monomers were supported by Fourier Transform Infrared (FT-IR), 1H-NMR and 13C-NMR spectral analysis, proving the existence of the benzoxazine ring containing eugenol moiety in its molecular structure. The monomers were polymerized/cured via ring-opening polymerization by heating as indicated by FT-IR and Differential Scanning Calorimetry (DSC). This is confirmed by the disappearance of the peaks due to oxazine ring (942 cm−1). The exothermic peak associated with curing was observed from 170 °C to 250 °C. The thermal and mechanical properties of the polybenzoxazines were investigated through thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The temperatures corresponding to 5% and 10% weight loss is from 240 to 295 °C and from 290 to 340 °C, respectively. The completely cured materials could achieve char yields up to 36.5% at 800 °C in nitrogen atmosphere. DMA revealed that the glass transition temperatures of PBz-SUL and PBz-PHE were higher than that of PBz-DDS and PBz-OXY.

Journal ArticleDOI
TL;DR: In this paper, a round-robin study combining differential scanning calorimetry (DSC) and atomic force microscopy (AFM) was conducted to investigate the relationship between the microstructures on a bitumen surface and the wax content.
Abstract: In the past years a wide discussion has been held among asphalt researchers regarding the existence and interpretation of observed microstructures on bitumen surfaces. To investigate this, the RILEM technical committee on nano bituminous materials 231-NBM has conducted a round robin study combining differential scanning calorimetry (DSC) and Atomic Force Microscopy (AFM). From this, methods for performing DSC and AFM tests on bitumen samples and determination of the influence of wax on the observed phases, taking into account thermal history, sample preparation and annealing procedure, are presented and critically discussed. DSC is used to measure various properties and phenomena that indicate physical changes such as glass transition temperature (T g) and phase transition such as melting and crystallization. In the case of existence of wax, either natural or synthetic, it can further indicate the melting point of wax, that could be used to determine wax content. The results from seven laboratories show that T g temperatures obtained from the heating scans are more repeatable and easier to obtain in comparison to the cooling scans. No significant difference was noted for T g's obtained from the first and second heating scans. AFM is an imaging tool used to characterize the microstructures on a bituminous surface. Using AFM three phases in the materials with wax could be distinguished. The changes in the phases observed with AFM for increases in temperature were correlated with the DSC curve, and it could be established that the so called "Bee" structure disappeared around the melting peak in the DSC curve. Thus, this research has confirmed the relation between the microstructures on a bitumen surface and the wax content. cop. 2013 RILEM.

Journal ArticleDOI
TL;DR: In this paper, the temperature range for cyclic reduction-oxidation and optimize the process parameters for maximum reduction and reoxidation extent was determined and the results showed that under proper operating conditions Co3O4 powders exhibited long-term (30 cycles), complete and reproducible cyclic reducing/oxidation performance within a temperature range 800-1000°C. Complete reoxification was achieved within reasonable times by performing the two reactions at close temperatures and by controlling the heating/cooling rate.

Journal ArticleDOI
TL;DR: In this paper, the authors have shown that ZnO acts as a network modifier with BiO6 octahedral structural units for glass samples with x = 5, 10, and 15.

Journal ArticleDOI
TL;DR: In this article, the authors focused on the preparation, characterization and determination of latent heat thermal energy storage (LHTES) properties of polystyrene (PS)/n-heptadecane micro/nano-capsules as a novel encapsulated phase change material (EPCM).

Journal ArticleDOI
TL;DR: In this paper, the effects of adding nitrogen-doped graphene (NDG) as a carbon nanofiller were examined experimentally, and the thermal stability and thermal properties of composite PCM were investigated with a thermogravimetric analyzer and differential scanning calorimeter (DSC), respectively.

Journal ArticleDOI
24 Mar 2014-Polymer
TL;DR: In this article, vanillin was used to synthesize polybenzoxazine with the expected desirable benzoxazine properties as well as a high char yield of 55.3%.