Films small angle scattering

A more quantitative measure of the microfibrillar morphology can be obtained by SAXS measurements. A detailed analysis of the small-angle scattering from PBT films and derivation of the relevant equations will be given elsewhere. The main features of the analysis are given below. 

X-ray film appropriate for small angle scattering accessory (optional, depending on the age of the instrument, computer and software)... 

Grazing incidence Optical microscopy Small-angle scattering Surface scattering Synchrotron radiation Thin film geometry... 

The first measurements of the small angle scattering during crystallization have been performed on polyethylene terephthalate by Eisner, Zachmann, and Milch . Amorphous films were oriented by stretching at 92 °C and crystallized afterwards... 

Measurements were performed up to now during isothermal crystallization at 117 °C of an initially amorphous film. Fig. 43 shows the scattering power Q = S I(s) ds of the small angle scattering as well as the degree of crystallinity obtained from wide angle scattering as a function of crystallization time. 

SAXS measurements were made at the National Center for Small Angle Scattering Research (NCSASR) at Oak Ridge National Laboratory using the 10m SAXS camera. The instrument used a rotating anode CuK (X" 0.1542 nm) x-ray source, crystal monochromatization of the incident beam, pinhole collimation, and a two dimensional, position sensitive, proportional counter. Sample to detector distance was 1.12 m. Disc-shaped samples were cut from the molded films and dried in a vacuum oven at 65 °C for four weeks prior to the SAXS analyses. 

Figure 2.13 Schematic elastic scattering curve of a spherical colloid (e.g. a microemulsion droplet) in solution. As a rule of thumb q 1 is an approximate measure for the spatial resolution of the used scattering experiment. At low values of q (i.e. in the Cuinier region of the scattering curve) the overall size and shape of the particles as well as correlations between different particles can be monitored (typically by static and dynamic light scattering). At high values q, the internal structure of the particles, i.e. the local structure of the interfacial film is resolved (e.g. by neutron or X-ray small angle scattering and neutron spin-echo spectroscopy (NSE)).

Graczyk (1978) has investigated the short range order structure, microstructure and compositional fiuctuations of thin films (such as GdCoMoArO) prepared by bias sputter. From his small angle scattering experiments he reports the presence of one halo which shifts with the rotation angle and decreases in intensity as this parameter increases. This clearly shows the anisotropic scatter-... 

Moss and Graczyk (1969) have observed a small angle scattering of electrons (another radiation suitable for diffraction) from a 100 A thick film of vapor deposited amorphous silicon. Upon annealing the film, the small angle scattered intensity is reduced. From their results they conclude... 

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