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Lamellar thickness distribution

DSC is another tool giving access to the lamellar thickness distribution. Based on the form of the DSC melting curve, the average distribution of the lamellae thickness may be determined. This procedure is based on the assumption that the melting temperature is related to the thickness L of a crystalline lamella, by the Thomson-Gibbs relationship [8] ... [Pg.381]

Keywords chain fold crystal growth, lamella, lamellar thickness distribution, nucleation, secondary crystallization, etching, lamellae detection, small angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), optical microscopy, spherulite, morphology, electron microscopy. [Pg.382]

FIG. 11 Lamellar thickness distribution histograms based on transmission electron microscopy results for PE annealed film at (a) 120°C, and (b) 130°C. (Reprinted from Ref. 139.)... [Pg.187]

Marigo, A., Marega, C., Zannetti, R., and Sgarzi, P. (1998) A study of the lamellar thickness distribution in 1-butene. 4-methyl-l-pentene and 1-hexene LLDPE by small and wide angle X-ray scattering and transmission electron microscopy. European Polymer Journal, 34, 597-603. [Pg.107]

FIGURE 31.10 Lamellar thickness distributions for all the material-geometry-rate combinations in study II with their respective control (undeformed) distributions [2],... [Pg.480]

At this point a third intermediate approach deserves mentioning. It is due to Allegra [43] who proposed that polymer crystallization is controlled by a metastable equilibrium distribution of intramolecular clusters, the so-called bundles , forming in the liquid phase. These subsequently aggregate to the side surfaces of the crystals, driven by van der Waals interactions. The lamellar thickness is determined by the average contour length of the loops within the bundles. Although the model can... [Pg.233]

The thickness of the ordered crystalline regions, termed crystallite or lamellar thickness (Lc), is an important parameter for correlations with thermodynamic and physical properties. Lc and the distribution of lamellar thicknesses can be determined by different experimental methods, including thin-section TEM mentioned earlier, atomic force microscopy, small-angle X-ray scattering and analysis of the LAM in Raman spectroscopy. [Pg.284]

One of the benefits of direct TEM observation is its possible accounting of the thickness of the crystalline and amorphous layers separately. The distributions of thickness for amorphous and crystalline layers are plotted in Figure 8.40 Both crystalline and amorphous thickness distribution curves have their individual maxima, whose positions are independent of prior polymer concentration. The peak top is always located at 9 nm for crystalline layer and 1.5 nm for the amorphous one. Their SAXS profiles are compared in Figure 9.40 The long periods lie in the constant position at around 0.75°, which corresponds to 11.5 nm thickness, independent of prior polymer concentration. As the lamellar thickness obtained by SAXS is the sum of thicknesses of the crystalline and amorphous phases, the average thickness of lamellae measured by TEM coincides with that by SAXS. Therefore, the morphologies seem to be independent of polymer concentration. [Pg.217]

Note The equilibrium melting temperature (tJJ,) of copolymers depends on the molecular weight, sequence distribution and counit content. The T, value is determined by two commonly used techniques the Hoffman-Weeks plot and the Thompson-Gibbs plot. Tire application of the Hoffman-Weeks method to determine the tJ, of a copolymer is unreliable (see reference 43). The more reliable method is to use the Tliompson-Gibbs relationship of Tm as a function of lamellar thickness, provided a large range of lamella thickness can be obtained. Considerable disagreement exists between different authors on the exact value of transition that can be identified for fhe copolymers. Consequently, values tabulated in this table must be used cautiously. See references (39, 43, and 44) for detailed discussions. [Pg.511]

Hosoda (1988) also studied Z-N-LLDPE. The MW and MWD were determined using SEC with a refractometer and LALLS. The SCB was calculated from FT-IR spectra, while SAXS provided information on the crystalline lamellar thickness. C NMR spectra of LLDPE solutions in o-dichlorobenzene (ODCB)/perdeuter-iobenzene provided the triad sequence distribution, average sequence length, and run number in ethylene/ -butene copolymer. There are many ways to display the plethora of results, but the most interesting is the global cross-plot of MWD and composition the authors called this the bird s-eye view presented in Fig. 18.6. [Pg.1576]


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