Crystallinity crystallite

New methods of computational analysis will be sought in order to provide simultaneous measures of crystallinity, crystallite-size and lattice distortion in fibrous polymers from X-ray diffraction patterns, but these must pass the test of application to fibres which can be partly characterized by means of electron-microscopy. 

Akai P, Merriman RJ, Roberts B, Peacor DR, To th M (1996) Crystallinity, crystallite size and lattice strain of illite-muscovite and chlorite Comparison of XRD and TEM data for diagenetic to epizonal pelites. Eur J Mineral 8 1119-1137... 

The calorimetric characteristics of iPP phase of the uncompatibilized blends show that the presence of the SBH dispersed phase leads to a slight increase of the PP temperature of crystallization (Fig. 17.8) (37,38). This result can be interpreted by a slightly increased nucleation rate of PP phase in the presence of SBH dispersed particles. As seen in Fig. 17.8, iPP temperature of crystallization increases drastically in the presence of COPP70 and COPP50. The analysis of the X-ray patterns (38) (Fig. 17.9a and b) and calculated parameters (dm values, degree of crystallinity, crystallite size, and intensity ratio) allows the assumption that PP segments of... 

The tortuosity expresses the average path length a diffusing molecule must travel. In a semicrystalline polymer, it would depend on the crystallinity, crystallite size and shape, and the distribution of crystallites in the amorphous matrix. is a measure of the effective restraint of the motion of polymer chains in the continuous region exerted by the discrete phase. 

Polymer samples have a thermal history due to processing, which influences the polymer properties, such as crystallinity, crystallite orientation, and consequently the thermomechanical properties. In DSC experiments typically the data of the second heating run are analyzed after the thermal history is erased through heating above the highest Ttrans in the first heating run. 

Knowledge of crystalline morphology is essential in understanding the permeability and permselectivity of polymer membranes such as dense membrane, dialysis membrane and gas separation membrane. X-ray is very common to study the crystallinity in polymeric membranes. Crystalline structure of a polymer membrane includes dimensions of unit cell, percentage of crystallinity, crystallite size, and orientation. The most generally applicable technique that provides information is the X-ray diffraction method. 

X-ray scattering techniques are the most commonly applied complementary discipline to microscopy for structural studies. The type of information that is obtained by x-ray scattering experiments includes phase identification and quantification, crystallinity, crystallite size, lattice constants, molecular orientation and structure, molecular packing and order, and amorphous structure [26-30]. Diffraction techniques that will be described include powder diffraction, wide angle x-ray scattering (WAXS), and fiber diffraction. Small angle x-ray scattering (SAXS) will be described in Section 7.4.4. 

Figure 5.26. Diagram showing the morphology of a semicrystalline polymer with a low degree of crystallinity (crystallites are ringed).

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