Phase Composition Nuclear Magnetic Resonance Spectroscopy

oxyapatite-rich domains can be found in areas with low ACP content and vice versa. 

After 10 s deposition time (a) only a few areas of the substrate were coated (light blue). Surface coverage increased after 30 s (b) and reached complete coverage after about 90 s (c, red and pink colours). 

Phase Composition Nuclear Magnetic Resonance Spectroscopy 

If a sample located in a magnetic field is subjected to radiofrequency (r.f.) radiation of an appropriate frequency, the atomic nuclei in the sample are able to absorb some of the energy provided. The frequency of the radiation required for this absorption of energy depends on three factors. First, it is characteristic of the type of nucleus (e.g. 1H or 31P). Second, the frequency depends on the chemical environment of the nucleus. For example, the proton associated with the hydroxyl 

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Phase Composition Nuclear Magnetic Resonance Spectroscopy I 325... 

Both vapor-phase chromatography and high performance Hquid chromatography, along with nuclear magnetic resonance spectroscopy, have been used for isomer and composition analysis. 

Instmmental methods of analysis provide information about the specific composition and purity of the amines. QuaUtative information about the identity of the product (functional groups present) and quantitative analysis (amount of various components such as nitrile, amide, acid, and deterruination of unsaturation) can be obtained by infrared analysis. Gas chromatography (gc), with a Hquid phase of either Apiezon grease or Carbowax, and high performance Hquid chromatography (hplc), using siHca columns and solvent systems such as isooctane, methyl tert-huty ether, tetrahydrofuran, and methanol, are used for quantitative analysis of fatty amine mixtures. Nuclear magnetic resonance spectroscopy (nmr), both proton ( H) and carbon-13 ( C), which can be used for quaHtative and quantitative analysis, is an important method used to analyze fatty amines (8,81). 

The flame retardant mechanism of PC/ABS compositions using bisphenol A bis(diphenyl phosphate) (BDP) and zinc borate have been investigated (54). BDP affects the decomposition of PC/ABS and acts as a flame retardant in both the gas and the condensed phase. The pyrolysis was studied by thermogravimetry coupled with fourier transform infrared spectroscopy (FUR) and nuclear magnetic-resonance spectroscopy. Zinc borate effects an additional hydrolysis of the PC and contributes to a borate network on the residue. 

In this chapter common methods to evaluate chemical properties and phase composition of bioceramic coatings will be briefly described that are available in many laboratories including X-ray diffraction (XRD), vibrational spectroscopy techniques such as infrared (FTIR) and Raman spectroscopy and nuclear magnetic resonance spectroscopy (NMR). These methods provide a host of information on bulk phase composition, degree of crystallinity and crystallite size. Some special techniques including cathodoluminescence serve to reveal intrinsic coating properties that cannot be assessed by conventional analytical techniques, for example to distinguish between amorphous calcium phosphate (ACP) and crystalline calcium phosphates. 

Carduner, K. R., Carter, R. O., Ill, Milberg, M. E., and Crosbie, G. M., Determination of phase composition of silicon powders by silicon-29 magic angle spinning nuclear magnetic resonance spectroscopy. Anal. Chem., 59, 2794 (1987). 

Yan et al. [52] explored the use of IPN techniques to produce a composite vinyl-acrylic latex. The first-formed polymer was produced using VAc and divinyl benzene (DVB), while the second formed polymer constituted a BA/DVB copolymer. In both cases the DVB was added at 0.4 wt%. They compared this product with another product, a bidirectional interpenetrating netwodc (BIPN) in which VAc was again polymerized over the first IPN. They noted that the compatibility between the phases was more pronounced in the BIPN than in the IPN as determined using dynamic mechanical measurements and C nuclear magnetic resonance spectroscopy. The concept of polymer miscibility has also been used to produce composite latex particles and thus modify the pafamance properties of VAc latexes. Bott et al. [53] describe a process whereby they bloid VAc/ethylene (VAc/E) copolymers with copolymers of acrylic acid or maleic anhydride and determine windows of miscibility. Apparently an ethyl acrylate or BA copolymer with 10-25 wt% AA is compatible with a VAc/E copolymer of 5-30 wt% ethylene. The information obtained from this woik was then used to form blends of latex polymers by polymerizing suitable mixtures of monomers into preformed VAc/E copolymers. The products are said to be useful for coating adhesives and caulks. 

Analyses of Pitch. Modern analytical facilities of high-pressure liquid chromatography, gel permeation chromatography, an(j 1 nuclear magnetic resonance and mass spectrometry, associated with 1R and UV spectroscopy enable a total molecular constituent analysis of pitch composition to be obtained. The use of such information could then possibly be the route to prediction of pitch quality on carbonization. It would appear that such an approach would not be successful (ignoring the cost factor for such detailed analysis). The pitch cannot be considered as an assembly of molecules which pyrolyse independently of each other. The pitch carbonizes as a multi-phase system and experience today would indicate the impossibility of predicting all interactions, physical and chemical. 

In this chapter we will give a review of recent advances in understanding the nature of the nematic phase transition in LCEs [3-5]. In addition, this chapter explores the possibiUties of controlling the critical behaviour of the nematic transition and, thus, the type of thermomechanical response. In Sect. 1, the nature of the nematic transition will be briefly discussed for pure liquid crystals (LCs) and LCEs. Sections 2 and 3 focus on the application of two essential experimental techniques, high-resolution ac calorimetry and deuteron nuclear magnetic resonance ( H-NMR) spectroscopy, to these systems. Section 4 explains the nature of the nematic transition in LCEs as revealed by the two techniques. Section 5 is devoted to experimental studies that systematically explored the possibilities of tailoring the TM response of LCEs by a variation of the chemical composition and other parameters during the synthesis. 

The different methodologies developed for the precise determination of the stereoisomeric composition of chiral compounds and chiral separation, such as gas and liquid chromatography on chiral stationary phases, capillary electrophoresis, and nuclear magnetic resonance (NMR) spectroscopy the methodologies for the determination of... 

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