Orientation Morphology, oriented

Mechanical Properties. The principal mechanical properties are Hsted in Table 1. The features of HDPE that have the strongest influence on its mechanical behavior are molecular weight, MWD, orientation, morphology, and the degree of branching, which determines resin crystallinity and density. 

The high patency rate of the small vessels is apparently favored because of the nature-orientated morphology of BASYC . These findings are evidence for a process of integration without degradation (vitalization). 

In addition, most semicrystalline polymers, particularly those produced commercially, are partially oriented i.e. their chains have an overall alignment that may impart to the bulk polymer certain advantageous properties, e.g. increased mechanical strength or dielectric polarizability. Molecular orientation, whether arising from crystallization under stress or deformation of a solidified polymer, or in naturally occurring oriented crystalline polymers such as cellulose or keratin, is always associated with an orientational morphology. 

Within the boundaries of the quiescent methods discussed here, these oriented morphologies do not propagate far into the bulk, but typically only a few tenths of microns. So it has been of interest to develop methods to impart an oriented structure throughout the bulk as well. Usually, these methods involve polymer deformation or flow. The following sections cover a discussion of the most common situations where deformation provides oriented morphologies. 

A common way to produce oriented morphologies or attain enhanced properties is to mechanically deform... 

Solid-state extrusion has also yielded some of the highest properties for uniaxially oriented morphologies. Tensile moduli (210 GPa) nearing the theoretical value of a polyethylene single crystal have been attained.f ... 

Shish-kebab" morphology (a different highly oriented morphology which develops when an oriented melt is crystallized)... 

Baji, A., Mai, Y.W., Wong, S.C., Abtahi, M. and Chen, P. 2010. Electrospinning of polymer nanofibers Effects on oriented morphology, structures and tensile properties. Composites ScL Technol. 70 703-718. 

Keywords biaxial orientation, film blowing, film tentering, structure of oriented PP, mechanical properties of oriented PP, BOPP, packaging, cast film, tubular film, inflation film, amorphous orientation, crystalline orientation, morphology, haze, optical properties, gloss, shrinkage, permeability... 

Aside from normal fiber patterns with the fiber axis coinciding with the molecular axis, bi-oriented morphologies are frequent in a-iPP films due to selfepitaxy related to the quadritic morphology. Patterns may result evidencing two distinct crystallite orientations, for which the a ... 

In the filling stage of injection molding, the polymer melt is subjected to high shear rates, which results in the so-caUed flow-induced crystallization (FIC). The main features of FIC are the dramatic enhancement of the crystallization rate, and the formation of oriented morphology. The effect of FIC continues after the cessation of flow. 

Geomembrane production imposes an oriented morphological structure on the material and thus freezes certain internal stresses. These stresses and the orientation are relaxed by heating and the dimensions of a test speci-... 

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