DSC Scans Research Articles

Enhanced thermal stability and optical properties in Tm3+/Dy3+ ions codoped TNbZ glasses

TNbZ host glasses within composition 90TeO2–10Nb2O5–10ZnO in mol% codoped with x(Tm2O3/Dy2O3), where x=0, 10000, 20000 and 30000ppm were prepared by using melt-quenching technique under dry oxygen streem. The thermal and optical properties of these glasses were estimated by using differential scanning calorimetric, DSC, and UV–vis-NIR spectroscopy respectively. The results of thermal analysis indicates that Tm3+/Dy3+ modified TNbZ host glass has high thermal stability and anticrystallization process. The density, oxygen packing density, molar volumes, oxygen molar volume, molar refraction, metallization criterion, molar polarizability, linear refractive index n, third-order non-linear susceptibility and two photon absorption coefficient were calculated. It was found that, the linear refractive index increases otherwise decrease in the optical energy gap with increase Tm3+/Dy3+ions. Raman scattering spectra and calculated Raman gain spectra of present glasses were studied. Addition of Tm3+/Dy3+ ions to TNbZ glasses increase in intensity due to distortion of [TeO4] units, Te-O-Te chains and [TeO3] units. The evaluated Raman gain coefficient of these glasses was found as 33–80 times that of fused-silica (0.89×10−13m/W) at 440cm−1. The results suggest that the present glass modified by Tm3+/Dy3+ may be promising candidate use in optical application like that Raman gain amplifier.

Synthesis and characterization of chitosan/poly (vinylpyrrolidone) biocomposite for biomedical application

CS/PVP blend membranes at different weight ratios were fabricated using a solution casting method and were characterized by measuring thickness, mechanical properties, water vapour transmission rate (WVTR), and water solubility. Membrane morphology and other characteristics were analysed using scanning electron microscopy, X-ray analysis, DSC, TGA, and ATR-FTIR spectroscopy. SEM and XRD showed that the CS/PVP was homogeneously dispersed in the membrane and the crystallinity decreased with increasing PVP content. The prepared membranes also showed good thermal properties. The strong interaction between the Chitosan and PVP contributed to improvement in the properties of the blend membranes. Membranes with CS/PVP = 1/1 blend ratio of chitosan/PVP showed the most satisfactory Hemolysis, TS, Elongation at break of all tested ratios. The antibacterial activity of the blend membranes was then investigated against Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. The PVP concentration contributes to antibacterial effect of the membranes and lower water vapour transmission rate. The in vitro hemolysis test of the membranes showed blood compatibility. These findings suggest that the CS/PVP as a promising material for biomedical application.

High Ionic Conductivity and Moduli Iongels Made with Tetraglyme/Litfsi /Methyl Cellulose for Lithium Batteries

The motivation for the development of solid polymer electrolytes (SPEs) arises from their safety advantages over liquid electrolytes. In particular SPEs are non-flammable and avoid the problem of electrolyte leakage, both of which can result in fires/explosions. However, SPEs have lower conductivities at room temperature (RT) compared to those of liquid electrolytes, so there is a need to develop SPE with improved RT conductivities. Recently, glymes, (CH3−O-(CH2−CH2−O)n−CH3) n=3 or 4, have been studied as solvents for non-aqueous electrolytes because of unique properties such as their solvation power (Lewis basicity), relatively long-lived (stable) solvates, and complex formation in certain molar ratios, [M(glyme)x]+, with alkali metal ions. Li(G3 or G4)][TFSI] is molten at room temperature and can be considered as a representative ionic liquid. It has very low volatility, is nonflammable, and has good oxidative stability. Here we report the preparation, ionic conductivity (s), mechanical and thermal properties of iongels made from Li(G4)TFSI and methyl cellulose (MC), in ratios of 90/10, 80/20 and 70/30 Li(G4)TFSI/MC. The ionic conductivity decreases with increase in MC content over the temperature range measured, 10 oC to 90 oC (Figure 1A), while the storage moduli increase with increase in MC content. For 90/10 Li(G4)TFSI/MC at 30 oC , s = 3.78×10-4 S/cm and the storage modulus = 50 MPa(Figure 1B). Thermogravimetric analysis of G4, Li(G4)TFSI, Li(G4)TFSI/MC and MC indicates that iongels are stable until the vaporization of the G4(Figure 2A). DSC data for G4, G4 with TFSI, and G4 with TFSI/MC (Figure 2B ) show that: (i) complexation of Li+ with G4 results in an increase in Tg and a suppression of the melt temperature Tm, and (ii) MC content increases Tg and decreases conductivity (Figure 1A). Figure 1A. Log (conductivity) versus 1000/T for Li(G4)TFSI and Li(G4)TFSI/MC gels. Figure 1B. Storage modulus for 90/10 Li(G4)TFSI/MC as a function of temperature Figure 2A.TGA of G4,Li(G4)TFSI, Li(G4)TFSI/MC and MC Figure 2B. DSC scans (second heating cycle) of Li(G4)TFSI and Li(G4)TFSI/MC References (1) Zhou, S.; Kim, D. Polymers for Advanced Technologies 2010, 21, 797. (2) Henderson, W. A. The Journal of Physical Chemistry B 2006, 110, 13177. (3) Pappenfus, T. M.; Henderson, W. A.; Owens, B. B.; Mann, K. R.; Smyrl, W. H. Journal of The Electrochemical Society 2004, 151, A209. Figure 1

Effect of chelating polymer as chelating agent on the PZT/PVDF pyroelectric composites

Pyroelectric composites of PZT/PVDF with 0–3 connectivity were prepared by hot-pressing technology. In the composite systems, the ethylene diamine tetraacetic acid (EDTA) was used as a chelating agent to modify the surface combination between the polymer phase and the dispersed filler phase, and its effects on the microstructure, thermal properties, volume conductivity, dielectric properties and pyroelectric properties were investigated in detail. The scanning electron microscope micrographs showed that the interaction between PZT and PVDF could be effectively improved by introducing EDTA. The FTIR spectra analysis and DSC scans indicated that with the increasing of EDTA addition, the crystallization of PVDF was enhanced gradually accompany with the emergence of a small amount of β-PVDF phase. Owing to the enhancement of chelation bonding, the thermal properties and volume conductivity were both optimized, which meant the interfacial adhesion and charge transfer became more efficient. As a result, the pyroelectric properties of the composites were significantly improved. Especially, with 0.6 wt% EDTA addition, the pyroelectric coefficient was raised to be about 30 % higher than that of the untreated composites.

Chemical kinetics on thermal decompositions of cumene hydroperoxide in cumene studied by calorimetry: An overview

Study on chemical kinetics related to the thermal decomposition of cumene hydoperoxide (CHP) in cumene is summarized in this work. It is of great importance to gather and compare the differences between these kinetic parameters for further substantial applications in the chemical industry and process safety. CHP has been verified to possess an autocatalytic behavior by using microcalorimetry (such as TAM and C-80) operated at isothermal mode in the temperature range from 70°C to 120°C. However, it exhibits a reaction of n-th order detected by non-isothermal DSC scanning and adiabatic calorimeter. By the isothermal aging tests, activation energy and frequency factor in logA(s−1) were averaged to be (117.3±5.9) kJmol−1and (11.4±0.3), respectively. Kinetic parameters acquired from data of interlaboratories by using heat-flow calorimetry, the averaged activation energy and frequency factor in logA(s−1) were (119.3±11.3) kJmol−1and (12.0±0.2), respectively. On the analogy of results from adiabatic calorimetry, the activation energy and frequency factor in logA(s−1) were respectively averaged to be (122.4±9.2) kJmol−1and (11.8±0.8). Five sets of kinetic models in relation to autocatalytic reactions are collected and discussed as well.

Phase transformation and thermal stability of ZnSe QDs due to annealing: emergence of ZnO

In the present study ZnSe quantum dots (QDs) were synthesized by chemical co-precipitation method using mercaptoethanol as the capping agent. These nanostructures were characterized for structure and surface morphology by using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectrometry respectively. The average size of ZnSe quantum dots from XRD and HRTEM is found to be 4–5 nm having cubic crystalline phase. Effect of annealing temperature, which were determined as phase transformation temperatures (299 and 426 °C) using differential scanning calorimetry has been investigated for structural and thermal stability of QDs. The XRD of annealed samples at temperatures 325 and 442 °C (slightly higher than the temperatures corresponding to two crystallization peaks in the DSC scan) have been carried out to find structural changes corresponding to these annealing temperatures. Sample annealed at 325 °C showed no change in the phase except improvement in intensity of peaks (crystallinity) whereas sample annealed at 442 °C showed transitions from cubic phase of ZnSe to ZnO and orthorhombic phases of ZnSeO4, ZnSeO3. Emergence of ZnO peaks in the XRD pattern of annealed samples have been further verified by Raman spectroscopy of the annealed samples. Besides this crystallization kinetics of ZnSe quantum dots has been employed to determine activation energies of these transitions due to oxidation by employing Kissinger, Augis Bennett and Ozawa’s models. Higher activation energy of crystallization corresponding to first crystallization peak shows that the cubic phase is more thermally stable.

Infusion of CO2 in a solid food: A novel method to enhance the low-frequency ultrasound effect on immersion freezing process

In this study, influence of infusion of CO (ICO) in a model solid food system (gelatin gel) was investigated during low-frequency ultrasound (LFU) assisted immersion freezing process. Low-frequency ultrasound will cause a rapid gas bubble formation in the CO infused food matrix enhancing the ice crystal nucleation. The freezing time, ice crystal size distribution and physico-chemical properties in the treated sample were investigated by Confocal Laser Scanning microscopy (CLSM), low-field NMR (LF-NMR), SEM, DSC, FTIR and TPA. The results indicated that infused CO can significantly (p < 0.05) decrease the freezing time and ice crystal size. The freeze-thawed samples subjected to combined ICO and LFU treatment had significantly (p < 0.05) lower water loss and higher gel strength and texture properties than the sample with LFU treatment only. LF-NMR study demonstrated that the combined treatment also influenced the water mobility and distribution of freeze-thawed samples. Compared to control sample, secondary structure of gelatin proteins of all the frozen samples changed significantly, α-helix decreased, while β-sheet and random coil increased. Industrial relevance The existence of CO in the samples promoted the crystallization of ice in solid food model during ultrasound assisted freezing process. Thus, the infusion of CO will have promising application in freezing of real foods (such as fruits and vegetables, dough, and fish).

Kinetics of the (solid + solid) transformations for the piracetam trimorphic system: Incidence on the construction of the p–T equilibrium phase diagram

The three common polymorphs of piracetam have been characterized by associating thermal analysis, X-ray diffraction and densimetry. DSC experiments showed that the (solid+solid) transition temperature between Forms II and I and between Forms III and I is scan-rate dependent. The transition temperatures decrease when the DSC scan rate decreases and the thermodynamic temperatures were confirmed by isothermal X-ray diffraction.These new results in terms of temperature and enthalpy of transition allow us to propose a new equilibrium phase diagram establishing the relative thermodynamic stability of the three common polymorphs of piracetam as a function of the temperature and the pressure.The diagram suggests that Form II presents a small stability domain located just above the stability domain of Form I. As a consequence, Form I should transform into Form II, which itself can turn into Form III when placed under pressure.

Imidazole-based deep eutectic solvents for starch dissolution and plasticization

Potato starch and high-amylose starch were treated with imidazole-based deep eutectic solvents (DESs) as dissolution and plasticization media. Beside imidazole (IM) for two-component DESs preparation choline chloride (CC), glycerol (G) or carboxylic acids (citric or malic) were used. An influence of water content in starch (as well as an extra water in the starch/DES system) on polymer dissolution and plasticization processes was investigated. Dissolution and gelatinization of starch in DESs were followed via DSC and laser scanning microscopy. A rheometric characteristics revealed an influence of starch/DES system storage time on the plasticization process. The tendency to recrystallization of compression-molded-starch films was evaluated using XRD technique. High dissolution and plasticization effectiveness of CC/IM and G/IM and a low tendency to film retrogradation of thermoplasticized starch were noted.

Kinetics of the epoxy–thiol click reaction initiated by a tertiary amine: Calorimetric study using monofunctional components

An analysis of the kinetics of the epoxy–thiol reaction in a model stoichiometric system of monofunctional reagents, 3-mercaptopropionate (BMP) and phenylglycidylether (PGE) is reported. Benzyldimethylamine (BDMA) was employed as initiator in amounts ranging from 0.5 to 2wt%. These formulations showed a kinetic behavior qualitatively similar to that of commercial adhesives and coatings formulated for a room-temperature cure. Isothermal DSC scans revealed the existence of a relatively long induction period preceding a fast autocatalytic reaction step. Dynamic DSC scans showed that the reaction was shifted to a lower temperature range by increasing the storage period of the initial formulation at 20°C. This unusual kinetic behavior could be modeled assuming that thiolate anions, slowly generated during the induction period, initiated a fast autocatalytic propagation/proton transfer reaction. The kinetic model included a pseudo-steady state for the initiator concentration and an equilibrium reaction between epoxy and OH groups generated by reaction. A reasonable fitting of isothermal and dynamic DSC runs was achieved in a broad range of temperatures and amine concentrations. In particular, both the length of the induction time and the effect of the storage period were correctly predicted.

Combined Spectroscopic and Calorimetric Studies to Reveal Absorption Mechanisms and Conformational Changes of Protein on Nanoporous Biomaterials.

In this study the effect of surface modification of mesoporous silica nanoparticles (MSNs) on its adsorption capacities and protein stability after immobilization of beta-lactoglobulin B (BLG-B) was investigated. For this purpose, non-functionalized (KIT-6) and aminopropyl-functionalized cubic Ia3d mesoporous silica ([n-PrNH2-KIT-6]) nanoparticles were used as nanoporous supports. Aminopropyl-functionalized mesoporous nanoparticles exhibited more potential candidates for BLG-B adsorption and minimum BLG leaching than non-functionalized nanoparticles. It was observed that the amount of adsorbed BLG is dependent on the initial BLG concentration for both KIT-6 and [n-PrNH2-KIT-6] mesoporous nanoparticles. Also larger amounts of BLG-B on KIT-6 was immobilized upon raising the temperature of the medium from 4 to 55 °C while such increase was undetectable in the case of immobilization of BLG-B on the [n-PrNH2-KIT-6]. At temperatures above 55 °C the amounts of adsorbed BLG on both studied nanomaterials decreased significantly. By Differential scanning calorimetry or DSC analysis the heterogeneity of the protein solution and increase in Tm may indicate that immobilization of BLG-B onto the modified KIT-6 results in higher thermal stability compared to unmodified one. The obtained results provide several crucial factors in determining the mechanism(s) of protein adsorption and stability on the nanostructured solid supports and the development of engineered nano-biomaterials for controlled drug-delivery systems and biomimetic interfaces for the immobilization of living cells.

Different types of V amylose–lipid inclusion complexes in maize extrudates revealed by DSC analysis

Aqueous dispersions of the extrudates (1%) prepared from three maize varieties containing starches with the various amylose contents (20–53%) and the high lipid level (about 7% on dry starch weight) were studied by DSC analysis. Two different types of amylose–lipid complexes were observed in the direct process (20–120°C, peak temperature of about 105–107°C) and when reheating/rescanning modes were employed (peak temperature of about 85°C). The extrudate dispersions heated only up to 100°C in the direct DSC scanning modes revealed a double‐peaked endothermic profile in the rescans that gave the evidence for coexistence of both types of the complexes. The possible reasons underlying formation, re‐formation, and/or coexistence of two types of the amylose–lipid complexes in the maize extrudates studied are discussed.

Thermophysical properties of bacterial poly(3‐hydroxybutyrate): Characterized by TMA, DSC, and TMDSC

ABSTRACTThe melting, isothermal and nonisothermal crystallization behaviors of poly(3‐hydroxybutyrate) (PHB) have been studied by means of temperature modulated differential scanning calorimetry (TMDSC) and conventional DSC. Various experimental conditions including isothermal/annealing temperatures (80, 90, 100, 105, 110, 120, 130, and 140°C), cooling rates (2, 5, 10, 20, and 50°C/min) and heating rates (5, 10, 20, 30, 40, and 50°C/min) have been investigated. The lower endothermic peak (Tm1) representing the original crystals prior to DSC scan, while the higher one (Tm2) is attributed to the melting of the crystals formed by recrystallization. Thermomechanical analysis (TMA) was used to evaluate the original melting temperature (Tmelt) and glass transition temperature (Tg) as comparison to DSC analysis. The multiple melting phenomenon was ascribed to the melting‐recrystallization‐remelting mechanism of the crystallites with lower thermal stability showing at Tm1. Different models (Avrami, Jeziorny‐modified‐Avrami, Liu and Mo, and Ozawa model) were utilized to describe the crystallization kinetics. It was found that Liu and Mo's analysis and Jeziorny‐modified‐Avrami model were successful to explain the nonisothermal crystallization kinetic of PHB. The activation energies were estimated in both isothermal and nonisothermal crystallization process, which were 102 and 116 kJ/mol in respective condition. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42412.

DBS investigation on films of cobalt chloride doped PVA-PVP blend

Films of Cobalt Chloride (CoCl2) doped polyvinylalcohol(PVA)- polyvinylpyrrolidone(PVP) blend (doped from 0.5 wt% up to 28 wt%) were prepared by solution casting, and characterized by XRD, DSC, UV-Visible Spectrometry TGA, FTIR and electrical measurements. In this paper, the results of Doppler Broadening Spectroscopy (DBS) in CoCl2 doped PVA-PVP blend is discussed. An increase in crystallinity of PVA-PVP blend, is observed, on doping it with CoCl2. The DBS results are complemented by XRD and DSC scans.

DBAR investigation on films of polypyrrole incorporated polyvinylalcohol doped with ferric chloride

Flexible films of pyrrole(Py) sorbed, ferric chloride (FeCl3) doped polyvinylalcohol(PVA) were prepared by solution casting. The films were characterized by XRD, UV-Visible spectrometry, Thermal Analysis (DSC, DTA/TGA), FTIR and electrical measurements. In this paper, the results of Doppler Broadening of Annihilation Radiation (DBAR) spectra in the doping range, from 4 wt% up to 18 wt%, are discussed. The XRD and DSC scans complement the DBAR results. The computed S- parameter and W -parameter reflect changes in the degree of crystallinity and the average crystallite size, respectively, of polypyrrole(PPy) incorporated PVA samples doped with ferric chloride.

Comment on “Water’s second glass transition, K. Amann-Winkel, C. Gainaru, P. H. Handle, M. Seidl, H. Nelson, R. Böhmer, and T. Loerting, Proc. Natl. Acad. Sci. (U.S.) 110 (2013) 17720.”, and the sub-Tg features of pressure-densified glasses

It is known that ambient pressure DSC scan of a glass formed by cooling a liquid under a high pressure shows a sub-Tg endotherm with a Cp peak, an exothermic minimum, and finally the true Tg-endotherm of the glass (A. Weitz, B. Wunderlich, J. Polym. Sci. Polym. Phys. 12 (1974) 2473). Amann-Winkel et al. (Proc. Natl. Acad. Sci. (U.S.) 110 (2013) 17720) reported that the ambient pressure DSC scan of eHDA, the expanded high density amorphous ice, cooled under a pressure of 0.07GPa shows onset of a Cp endotherm at 116K. Unaware of the studies of pressure-densified glasses, they regarded this onset as a second glass transition of water at 116K involving translational mobility. We show that: (i) their eHDA at 0.07GPa and 140K was ultraviscous water of high density, and the ex situ DSC scans were obtained for the recovered glassy solid that formed on cooling this water under 0.07GPa pressure to 90K, (ii) decrease in the onset temperature of the 116K endotherm they found on decreasing the cooling rate, and used as a typical signature of glass-transition, is not a signature of glass transition – and this rules out the possibility of this endotherm being a glass transition endotherm – nor are the methods claimed to be standard are standard or reliable methods, (iii) the DSC scans of the recovered glassy solid at ambient pressure are qualitatively similar to those found for pressure-densified glasses, and (iv) the experimental procedure and data analysis of the dielectric relaxation study is too inaccurate to reliably support the view that water has a second Tg. We conclude that the rise in Cp at 116K is the sub-Tg endotherm of pressure-densified glassy water, i.e., water has only one Tg in the DSC scan at ambient pressure. We also describe other findings on pressure-densified glasses, and the possibility of their sub-Tg mobility affecting certain irreversible processes, and suggest experiments for investigating why a glass formed by cooling under high pressure has different properties at ambient pressure than a glass formed by cooling at ambient pressure.

Study of the Thermal and Structural Properties of PVA/HPC Blends Due to Fast Neutrons Irradiation

Blends of PVA/HPC are prepared using solution casting method and are irradiated with fast neutron irradiation of fluence 1.15 x 107 n/cm2 to use as biomaterials according to their broad importance in practical and medical applications. Thermal properties and structural configuration of the blends are studied to characterize and reveal the miscibility map of such blend system. The obtained results of the thermal analyses [differential scanning calorimetry, DSC, and thermal gravimetric analysis, TGA] show variations in the first order thermodynamic transition (Tth), the melting temperature, shape and area of thermal peaks which are attributed to the different degrees of crystallinity and the existence of interactions between PVA and HPC molecules. The X-ray diffraction patterns (XRD) show broadening and sharpening of peaks at different HPC concentrations with PVA and irradiation with fast neutrons. The results obtained indicate changes in the crystallinity/amorphosity ratio, and explains the possibility of miscibility existence between the amorphous components of the two polymers PVA and HPC.

ENCAPSULATION OF L-ASCORBIC ACID WITHIN THE NATURAL BIOPOLYMER-GALACTOMANNAN-USING THE SPRAY-DRYING METHOD: PREPARATION, CHARACTERIZATION, AND EVALUATION OF ANTIOXIDANT ACTIVITY

In this study, the spray drying technique was used to prepare L-ascorbic acid (AA) microparticles encapsulated with galactomannan-an extract from the seeds of the Delonix regia species. The physico-chemical characteristics, antioxidant activity, and encapsulation efficiency of the AA microparticles were evaluated and characterized using thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The free-radical scavenging activity of the AA microparticles was determined at different environmental conditions using DPPH (1,1-diphenyl-2-picryl-hydrazyl). X-ray diffraction measurements demonstrated a loss of crystallinity in AA after the encapsulation process, and a DSC scan also showed the loss of the compound's melting peak. Thermogravimetric analysis showed small differences in the thermal stability of galactomannan before and after the incorporation of AA. The mean diameters of the obtained spherical microspheres were in the range of 1.39 ± 0.77 µm. The encapsulation efficiency of AA microparticles in different environmental conditions varied from 95.40 to 97.92, and the antioxidant activity showed values ranging from 0.487 to 0.550 mg mL-1.

Bayesian estimation of cerebral perfusion using reduced-contrast-dose dynamic susceptibility contrast perfusion at 3T.

DSC perfusion has been increasingly used in conjunction with other contrast-enhanced MR applications and therefore there is need for contrast-dose reduction when feasible. The purpose of this study was to establish the feasibility of reduced-contrast-dose brain DSC perfusion by using a probabilistic Bayesian method and to compare the results with the commonly used singular value decomposition technique. Half-dose (0.05-mmol/kg) and full-dose (0.1-mmol/kg) DSC perfusion studies were prospectively performed in 20 patients (12 men; 34-70 years of age) by using a 3T MR imaging scanner and a gradient-EPI sequence (TR/TE, 1450/22 ms; flip angle, 90°). All DSC scans were processed with block circulant singular value decomposition and Bayesian probabilistic methods. SNR analysis was performed in both half-dose and full-dose groups. The CBF, CBV, and MTT maps from both full-dose and half-dose scans were evaluated qualitatively and quantitatively in both WM and GM on coregistered perfusion maps. Statistical analysis was performed by using a t test, regression, and Bland-Altman analysis. The SNR was significantly (P < .0001) lower in the half-dose group with 32% and 40% reduction in GM and WM, respectively. In the half-dose group, the image-quality scores were significantly higher in Bayesian-derived CBV (P = .02) and MTT (P = .004) maps in comparison with block circulant singular value decomposition. Quantitative values of CBF, CBV, and MTT in Bayesian-processed data were comparable and without a statistically significant difference between the half-dose and full-dose groups. The block circulant singular value decomposition-derived half-dose perfusion values were significantly different from those of the full-dose group both in GM (CBF, P < .001; CBV, P = .02; MTT, P = .02) and WM (CBF, P < .001; CBV, P = .003; MTT, P = .01). Reduced-contrast-dose (0.05-mmol/kg) DSC perfusion of the brain is feasible at 3T by using the Bayesian probabilistic method with quantitative results comparable with those of the full-dose protocol.

Analysis of non-isothermal crystallization during cooling and reorganization during heating of isotactic polypropylene by fast scanning DSC

Crystallization, reorganization and melting of isotactic polypropylene (iPP) were analyzed by DSC and fast scanning DSC. The cooling and subsequent heating DSC curves are measured at scanning rates between 0.1K/min and 30,000K/s. We study the formation of the mesophase and the α-phase during cooling. Using subsequent heating measurements the formation of the mesophase during cold crystallization and the kinetics of the reorganization are analyzed. From the cooling rate dependence of the glass transition and the melting behavior we discuss relations between the crystalline fraction (CF), the mobile amorphous fraction (MAF), the rigid amorphous fraction (RAF) and the influence of these fractions on the reorganization processes. Furthermore, we use the heating rate dependence of the melting behavior for stability analyses of the related crystals and propose the Illers-plot as a simple analysis tool. Using this technique the melting temperature of the mesophase is determined to about 86°C.