Wide-angle scattering

PVC has a complex particle morphology and a low degree of crystallinity. The crystallinity of PVC increases with increase in syndiotacticity. The level of syndiotacticity rises with fall in the temperature of polymerisation, and in the case of commercial types of PVC-S reaches 54-56%, whereas their crystallinity is only about 10%. The presence of crystalline forms in PVC has been established by studies using e.g. small-angle x-ray scattering, wide-angle X-ray diffraction (WAXS), IR spectroscopy and differential scanning calorimetry (DSC). In PVC, crystallites are formed under conversion conditions of less than 2%. These... 

The second recent work which must be mentioned is the in-situ combined small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) monitoring of an all-silica ZSM-5 crystallization [57, 58]. The combined technique allows one to simultaneously observe particles in the system, to determine their fractal dimension, and to determine the level of crystallinity within the particles, and the crystalline phase(s) present. Based on the data collected, some of which is reproduced in Fig. 6, the authors proposed the nucleation mechanism depicted in Fig. 7. In essence, the authors suggested that primary silica particles formed quite early in the process, perhaps of the nature described by... 

Bark, M., and Zachmann, H.G. Simultaneous measurements of smaU-angle X-ray-scattering, wide-angle X-ray-scattering and heat-exchange during crystallization and melting of polymers. Acta Polym. 44 no. 6 (1993) 259-265. 

Cakmak M, Teitge A, Zachman FI G and White J L 1993 On-line small-angle and wide-angle x-ray scattering studies on melt-spinning poly(vinylidene fluoride) tape using synchrotron radiation J. Polym. Sc/. 31 371- 81... 

Copolymers of vinyUdene chloride and methyl acrylate have been studied by x-ray techniques (75). For example, the long period (lamellar thickness) for an 8.5 wt % methyl acrylate copolymer was found to be 9.2 nm by smaH-angle x-ray scattering. The unit cell is monoclinic, with a = 0.686 and c = 1.247 nm by wide-angle x-ray scattering. 

Polyetherimides show no crystallinity as evidenced from calorimetry measurements. The heteroarylene like phenylquinoxaline [27], oxadiazole [30], and benzoxa-zole [56] activated polyethers show TgS from DSC thermograms, with no evidence of crystallization, indicating amorphous or glassy morphology. Furthermore, wide angle x-ray scattering measurements show no evidence of crystalline or liquid crystalline type morphologies, consistent with an amorphous structure. F polyether... 

Tsou and Measmer examined the dispersion of organosUicates on two different butyl mbbers, namely BIMS and brominated poly(isobutylene-co-isoprene) (BIIR) with the help of small angle X-ray scattering (SAXS), wide angle X-ray scattering (WAXS), atomic force microscopy (AFM), and TEM [91]. There is also a patent on BIMS nanocomposites for low permeability and their uses in tire inner tubes [92]. 

Transmission electron microscopy for [Pd/l]coii reveals the presence of small spherical but in some cases agglomerated particles of ca. 4 nm mean size, and wide angle X-ray scattering analyses evidence the fee structure of bulk palladium [44] (Figure 1). 

A Siemens Kratky camera system was utilized for small angle x-ray scattering (SAXS) measurements in conjunction with an M. Braun position sensitive detector from Innovative Technology Inc.. Wide angle x-ray diffraction was obtained utilizing a Philips table-top x-ray generator. 

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