Relative degree of crystallinity

In order to compare the crystallinities of the polyarylates, X-ray diffraction patterns were observed in the temperature range of 25-250 °C, with the relative degree of crystallinity (I/I0) being calculated according to the following equation  

The morphologies of the tensile-fractured as-spun fibers and the flexural-fractured injection molded specimens were studied by scanning electron microscopy (SEM). 

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Ryan [36] developed a method to determine the relative degree of crystallinity (RDC) of imipenem in lypophilized combination products containing imipenem and amorphous cilastatin sodium. He used the relationship... 

Fig. 7 Relative integrated intensities under the peaks (left scale) and relative degree of crystallinity (right scale) obtained from wide-angle X-ray scattering data for D7732C2310 quenched from T = 115 to 30°C. The cooling rate was 30°Cmin 1. The arrow indicates the nominal point at which the final temperature was reached. For convenience, the amorphous peak intensity has been divided by 5. (Reprinted with permission from [ 107]. Copyright 2003 American Chemical Society)...

The relative degree of crystallinity can also be estimated from the WAXS pattern from the ratio of the integrated intensity of the crystal peak to that of the total amorphous and crystalline scattering (Balta-Calleja and Vonk 1989). For PE, the amorphous scattering below the (110) peak (Fig. 5.7) is relatively insensitive to the degree of crystallinity, so the integrated area of the (110) reflection compared to the broad amorphous halo is directly proportional to XPE. However, the absolute degree of crystallinity cannot be determined in this way (Ryan et al. 1995). 

Fig. 535 Avrami plots showing the growth of the relative degree of crystallinity (

Infrared Crystallinity Index. A measure of the relative degree of crystallinity was determined from the infrared spectra obtained in the preceding section by reporting the ratio of the optical density of the band at 1372"1 (7.29/mi) to that at 2900 cm 1 (3.45/xm). According to Nelson and O Connor (15), the crystallinity index measured in this way compares well with data from x-ray diffraction, density measurements, and accessibility measured by moisture sorption. 

The relative degree of crystallinity, Xt, was determined from the partial area under the DSC exotherm defined as follows ... 

The regularity of the linear macromolecular chains of PEO, as illustrated in its chemical structure shown in Figure 8, enables the polymer to acquire a high degree of crystallinity (X)of -70-80%. The relative degree of crystallinity (A) for PEO applied in this book chapter is evaluated from the enthalpy of fusion (A// ) of PEO extracted from the area of the melting curve of PEO in the reheating cycle of the DSC trace of the sample after Equation (8) ... 

Figure 6.8. Dependence of the activation energy on the relative degree of crystallinity of neat propylene-ethylene copolymer (PP-R) and copolymer containing proprietary P-nucleating agent (PP-RCT). [Adapted, by permission from Papageorgiou, D G Papageorgiou, G Z Bikiaris, D N Chrissafis, K, Eur. Polym. J., 49, 1577-90, 2013.]...

The degree of crystallinity of polymers crystallized isothermally from the melt can be measured by DSC. The experimental procedure is described in Section 4.2.6. The relative degree of crystallinity (t) = 1 - ft was analyzed according to the usual procedure using equation (4.41). 

As an example, the relative degree of crystallinity of pure isotactic polypropylene (PP) is shown in Figure 4.24 as a plot a t) against time t. The isotactic PP sample, (PP 1300, obtained from Yanshan Petrochemical, Beijing, China) has a... 

Figure 4.24 Development of relative degree of crystallinity with time for isothermal crystallization of i.sotactic PP 34]...

Traditional Approaches. For many purposes, relative degrees of crystallinity (sometimes referred to as the crystallinity index) are sufficient and a number of approximate wide-angle X-ray diffraction (WAXD) methods have been reported and utilized. Before the advent of modem computational tools, WAXD patterns were simply resolved into contributions from crystalline and amorphous reflections, and a polynomial background (1). The degree of crystallinity was then calculated as hKh +1 ), where / is the diffracted intensity from all resolved crystalline reflections, /a the diffraction intensity under the amorphous halo, and (7c -I- 7a) the total intensity. This was an improvement over older work where peak separation was carried out arbitrarily (eg, by simply constmcting a line between intensity minima this results in lower determined crystallinity). 

The relative degree of crystallinity and the geometrical aspect ratio of obtained cellulose nanocrystals, depend on cellulose origin and the processing conditions, such as time, temperature, and original raw material purity. 

Fig. 6. The relationship between the relative degree of crystallinity of LOR and the relative composition of inclusion complex in the grinding course.

The relative degree of crystallinity, <, of a diblock copolymer containing polyethylene was measured as a function of time following a quench to T = 95 °C (i.e. less than T ), with the following results ... 

Figure 7. Relative degree of crystallinity of (a) PEN and (b) the PEN/CNT 0.1 nanocomposites as a function of temperature at various cooling rates.

Integration of the exothermic peak the non-isothermal crystallization can give the relative degree of crystallinity as function time. Figure 14.7 shows the normalized graph of relative crystallinity % V5. time for nylon-6 and nanocomposite samples (replica 1). Though nucleation occurs earlier the crystals in nanocomposites grow very slowly compared with the neat nylon-6 sample. 

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