Crystalline orientation function polypropylene

The features of the Nadella study are similar to those observed for polypropylene by other authors. The variations in the crystalline orientation functions are also similar to those reported for high-density polyethylene. Dees and Spruiell [196] interpreted these variations for polyethylene to indicate spherulitic structure at low spinning stresses but which undergo a... 

Similar measurements have been made by Samuels - on as-spun and drawn polypropylene fibres and they are correlated with crystalline orientation functions, light and low angle X-ray scattering studies. 

For semi-crystalline polymers, the average orientation function 2 for the crystal c axes can be calculated from X-ray diffraction measurements (Chapter 3). Figure 8.15 shows how 2 increases linearly with the draw ratio, for polypropylene fibres and films, while the spherulitic microstructure survives. At 2 = 0.9, where the spherulites are destroyed and replaced by a microfibrillar structure, there is an increase in the slope of the 2 versus true strain relationship. It is impossible to achieve perfect c axis orientation... 

In some crystalline systems where there are no reflecting planes normal to the desired crystallographic direction, one can still obtain the orientation for this direction providing the crystalline structure is defined. This method has been developed by Wilchinsky, where he showed that by measuring the orientation functions associated with various known hkl) planes, one can calculate the value of the desired orientation function. This method should not be confused with the application of the direction cosines relationship as discussed earlier. A specific example is given for the case of polypropylene in eqn. (22) where the value of ooi, can be found (and therefore the orientation of the chain axis) by measuring the diffraction from the (110) and (OkO) planes." " ... 

Bhattacharyya, A Sreekumar, T. liu, T. Kumar, S. Ericson, L. Hauge, H. Smalley, R. (2003) Crystallization and Orientation Studies in Polypropylene/Single Wall Carbon Nanotube Composite. Polym. Vol.44, N0.8, pp.2373-2377, ISSN 0032-3861 Bilotti, E. Fischer, H. Peijs, T. (2008) Polymer nanocomposites based on needle-like sepiolite clays Effect of functionalized polymers on the dispersion of nanofiller, crystallinity, and mechanical properties, f. Appl. Polym. Sci. Vol.107, No.2 pp.lll6-1123, ISSN 0021-8995... 

In addition to the modeling efforts, tho-e are some experimental rqxrrts in the literature. Canning et al. [10] made measurements of the film torsion, velocity and width profiles. Lamberti et al. [11, 12] investigated crystallinity and orientation in the film as a function of draw ratio. Aciemo et al. [3] studied the terrrperature profiles in PET films. Seyfzadeh et al. [4] made point wise measurements of the velocity, width and temperature profiles for film casting of PET. Aniimoh and Harrison [13] studied the effects of draw ratio and die temperature on polypropylene film easting. 

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