X-ray diffraction and differential scanning calorimetry

Thus, chiral discrimination may be observed that differentiates the force-area curves of the enantiomers of some surfactants from their racemic modifications. Apparent phase changes in the monolayer can be related to parallel behavior in the crystalline state through X-ray diffraction and differential scanning calorimetry. Formation of racemic compounds and quasi-racemates can be observed in some cases. 

Ollivon, M., Loisel, C., Lopez, C., Lesieur, P., Artzner, F., Keller, G. 2001. Simultaneous examination of structural and thermal behaviours of fats by coupled X-ray diffraction and differential scanning calorimetry techniques application to cocoa butter polymorphism. In, Crystallization and Solidification Properties of Lipids (N. Widlak, R. Hartel, S. Narine, eds.), pp. 34-41, AOCS Press, Champaign, IL. 

In this chapter we investigate the morphology of a series of polyurethanes based on polycaprolactone polyol (PCP), diphenylmethane diisocyanate (MDI), and butanediol (BDO). Samples of as-batch-reacted and solution-cast polymers were examined by optical microscopy, transmission electron microscopy, electron and x-ray diffraction, and differential scanning calorimetry. Our interest is to provide a mapping of the size and shape of the domains (and any superstructure such as spherulites) and the degree of order as a function of the fraction of each phase present. 

Simultaneous Examination of Structural and Thermal Behaviors of Fats by Coupled X-ray Diffraction and Differential Scanning Calorimetry Techniques Application to Cocoa Butter Polymorphism... 

Previous works reported on the study of the freezing process of aqueous solutions of ethanol in relation with the phase diagram. They were focused on the identification of different stable or metastable ethanol-hydrate structures using X-ray diffraction and differential scanning calorimetry (DSC). They also mentioned the formation of clathrate hydrates. In spite of the familiarity of alcohol-water systems and their importance in many fields of chemistry, cryobiology, astrophysics, there are still significant discrepancies in the literature with uncertainties concerning the composition and the structure of the stable or metastable eutectic or peritectic hydrates. ... 

Copolymers containing up to 35 wt % carboxylated vinyl ether were synthesized by regulating reaction pressure of the tetrafluoroethylene in the polymerization. X-ray diffraction and differential scanning calorimetry showed that the crystallinity of the copolymer decreased with increasing vinyl ether content. 

A Makriyannis, T Mavromoustakos. Studies on drug-membrane interactions using solid state NMR, small angle X-ray diffraction, and differential scanning calorimetry. Epitheor Klin Farmakol Farmakokinet, Int Ed 3 95-114, 1989. 

G. Z. Papageorgiou, G. P. Karayannidis, D. N. Bikiaris, A. Stergiou, G. Lit-sardakis, and S. S. Makridis. Wide-angle x-ray diffraction and differential scanning calorimetry study of the crystallization of poly(ethylene naphthalate), poly(butylene naphthalate), and their copolymers. J. Polym. ScL, Part B Polym. Phys., 42(5) 843-860, March 2004. 

Papageorgiou GZ, Karayannidis GP, Bikiaris DN, Stergiou A, Litsardakis G, Makridis SS, et al. Wide-angle x-ray diffraction and differential scanning calorimetry study of the crystallization of poly(ethylene naphthalate). 

A combination of X-ray diffraction and differential scanning calorimetry has been used to probe the properties of a homologous series of saturated l,2-di-0-acyl-2-0-(P-D-galactopyranasyl)-sn-... 

We can investigate a polymer s molecular and supermolecular organization in various ways, which provide information on either a direct or indirect basis. For instance, microscopy of various types provides us with images of small regions of polymers, allowing us to directly visualize certain types of structure. Other methods, such as X-ray diffraction and differential scanning calorimetry, sample larger volumes of material and provide information representative of the material as a whole. 

Electrochemical synthesis of polyacetylene was carried out with platinum foil as cathode and nickel foil as anode with nickel bromide in acetonitrile as an electrolyte at room temperature to precipitate in the form of powder in the cell [101]. Chen and Shy [53] observed a thin layer of black material on a surface of the platinum cathode when a voltage of 4-40 V was applied for about 50 min. During this stage, no precipitation of polyacetylene was observed in the solution. The material has the same chemical structure as those produced by the standard Ziegler-Natta catalyst as examined by elemental analysis, infrared spectroscopy. X-ray diffraction, and differential scanning calorimetry. 

Many papers deal with the crystallization of polymer melts and solutions under the conditions of molecular orientation achieved by the methods described above. Various physical methods have been used in these investigations electron microscopy, X-ray diffraction, birefringence, differential scanning calorimetry, etc. As a result, the properties of these systems have been described in detail and definite conclusions concerning their structure have been drawn (e.g.4 13 19,39,52)). 

Hydration of phospholipid head groups is essential properties not only for stabilizing bilayer structures in an aqueous environment, but also for fusion or endocytosis of biological membranes including protein transfers [33-35]. Hydration or swelling behavior has only been studied by indirect methods such as X-ray diffraction [36], differential scanning calorimetry (DSC) [37], and H-NMR [38,39]. 

Titanium sulfate supported on zirconia catalysts were prepared by drying of powdered Zr(OH)4 with titanium sulfate aqueous solution followed by calcining in air at high temperature. The characterization of prepared catalysts was performed using Fourier transform infrared (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and by the measurement of surface area. The addition of titanium sulfate to zirconia shifted the phase transition of ZrOa from amorphous to tetragonal to higher temperature because of the interaction between titanium sulfate and zirconia. The catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation were correlated with the acidity of catalysts measured by ammonia chemisorption method. 

The evidence from wide angle x-ray scattering (WAXS), differential scanning calorimetry (DSC), and IR spectroscopy (IR) shows that both polymers crystallize separately according to their own unit cell structure. The WAXS diffraction lines of each component are present in the blends no new bands appear (12,13,14). By DSC one observes the melting peaks corresponding to each polymer (Figure 1), and IR shows the typical characteristic crystalline bands of the pure polymers in the blends. The IR spectra of the blend can essentially be accounted for as the sum of the spectra of the components. 

Synchrotron-x>ray powder-diffraction and differential-scanning-calorimetry measurements on solid Cso reveal a first-order phase transition from a low-temperature simple-cubic structure with a four-molecule basis to a face-centered-cubic structure at 249 K. The free-energy change at the transition is approximately 6.7 J/g. Model fits to the diffraction intensities are consistent with complete orientational disorder at room temperature, and with the development of orientational order rather than molecular displacements or distortions at low temperature. 

X-ray diffraction studies are usually carried out at room temperature under ambient conditions. It is possible, however, to perform variable-temperature XPD, wherein powder patterns are obtained while the sample is heated or cooled. Such studies are invaluable for identifying thermally induced or subambient phase transitions. Variable-temperature XPD was used to study the solid state properties of lactose [20], Fawcett et al. have developed an instrument that permits simultaneous XPD and differential scanning calorimetry on the same sample [21], The instrument was used to characterize a compound that was capable of existing in two polymorphic forms, whose melting points were 146°C (form II) and 150°C (form I). Form II was heated, and x-ray powder patterns were obtained at room temperature, at 145°C (form II had just started to melt), and at 148°C (Fig. 2 one characteristic peak each of form I and form II are identified). The x-ray pattern obtained at 148°C revealed melting of form II but partial recrystallization of form I. When the sample was cooled to 110°C and reheated to 146°C, only crystalline form I was observed. Through these experiments, the authors established that melting of form II was accompanied by recrystallization of form I. 

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