Scattering, intensity, cellulose

Aqueous hydroxypropyl cellulose solutions amplification vs. wave number, 275,277/ apparent diffusivity vs. temperature, 275,277/ calculation of maximum scattered intensity, 278... 

There are several practical techniques for the determination of crystallinity. The peak resolution method is based on the approach of Hermans and Weidinger (1950) which was used on cellulose. A 20 scan including the intensive crystalline peaks and the amorphous halo is made. The diffractogram of the semicrystalline polymer consists of sharp Bragg reflections of the total intensity and an amorphous halo with a total scattered intensity I. The mass crystallinity (loj is determined from the following equation ... 

Surface fractal analysis has been applied to the study of the breakdown of cellulose fibers using ILs, where it is shown that the IL pretreatment time influenced the surface morphology of the resulting biomass [47], Such a surface is also common in glasses [48] and rocks [49] where the pore wall is rough as shown in Fig. 6.7. For surface fractals, it can be shown that the scattering intensity decays at high q by the equation ... 

The details of the synthesis method are as follows A substrate monomer of p-cellobiosyl fluoride first synthesized and purified (10.3 mg, 2.9 x 10" mol purity 95%) was solubilized in 170 pi of acetate buffer in D2O (CH3COOH/ CH3C00Na/D20) (pD = 5.0, 0.05 M). To this solution acetonitrile (1000 pi) was added. D2O was used to enhance the scattering contrast for SANS and USANS from the self-assembled cellulose molecules and enzymes against the reaction medium as well as to reduce the incoherent scattering intensity level of the system. The polymerization was started by mixing the above solution, designated as solution A, with 30 pi of acetate buffer in D2O (pD = 5.0,... 

The crystallinities of cellulose are obtained from X-ray diffraction techniques, which give the most direct results, although their interpretation and evaluation is still under discussion and widely based on convenience. On the basis of the two-phase fringed-micellar structure, Hermans and Weidinger derived a theory on the proportionality of the intensity or amplitude of scattering from the amorphous and... 

The intensity of the low angle scattering must also depend upon the absolute difference between the electronic densities of the crystallites and the medium between them For water this difference is 0.294, for toluene it is 0.379, for ethyliodide 0.016 and for methylene iodide 0.057. By imbibing cellulose filaments swollen in water first with alcohol and then by other organic liquids, Kratky et al showed that the experiments are in qualitative agreement with these figures As Fig. 49 shows, the intensity was almost zero in ethyliodide and very intense in water... 

The foregoing applies exclusively if intermicellar swelling is concerned. In cases in m ramicellar swelling, a considerable intensity of the low angle scattering is not to be expected. It was shown by Kratky that in swelling cellulose acetate in various... 

As already mentioned, the particle size and particle size distribution of cellulose fibers depend on the structure of the source, acid concentration, temperature, time of hydrolysis, and the applied mechanical treatment. It was found that cellulose fibers quickly form aggregates with various dimensions when they are suspended in water. In a study [27,28], the analysis of two samples of cellulose fibers by DLS revealed different sizes of cellulose fiber aggregates depending on the duration of the applied acid treatment. Dynamic light scattering results highlight the important influence of the acid hydrolysis duration on the intensity of MCC defibrillation process. 

The SAXS method allows measure the diameter of nano-size structural defects and pores. The small-angle scattering of the cellulose sample was recorded, and intensity was measured as a function of the diffraction angle. To correct the intensity, /, the background scattering was subtracted and the experimental intensity was corrected on instrumental factor, absorption of X-ray and other factors. Porod s law / = Kq, was used for visualization of the small-angle X-ray scattering (Porod, 1951, 1952]. Linearization of the experimental curves was performed as + kq or Y = Yg + kX (Fig. 7.13], where Y = and... 

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