Polymer processing oriented morphologies

The present review shows how the microhardness technique can be used to elucidate the dependence of a variety of local deformational processes upon polymer texture and morphology. Microhardness is a rather elusive quantity, that is really a combination of other mechanical properties. It is most suitably defined in terms of the pyramid indentation test. Hardness is primarily taken as a measure of the irreversible deformation mechanisms which characterize a polymeric material, though it also involves elastic and time dependent effects which depend on microstructural details. In isotropic lamellar polymers a hardness depression from ideal values, due to the finite crystal thickness, occurs. The interlamellar non-crystalline layer introduces an additional weak component which contributes further to a lowering of the hardness value. Annealing effects and chemical etching are shown to produce, on the contrary, a significant hardening of the material. The prevalent mechanisms for plastic deformation are proposed. Anisotropy behaviour for several oriented materials is critically discussed. 

During polymer processing non-isothermal crystallization conditions, mechanical deformation, and shear forces may alter the morphology and orientation of polymers both at the surface and in the bulk. In addition, orientation effects of semicrystalline polymers that crystallize in contact with solids are considered. 

In the case of the polymer strands oriented perpendicularly to the electrodes surface, the processes of charge injection and charge transport are strongly dependent on the morphology of the polymer layer. First, since all the strands are perpendicular... 

Figure 1 Rolltrusion processing schematic (a) triaxial orientation process (b) morphological schematic of the unprocessed and processed polymer with an enlarged insert depicting a crystallite with tie-molecule connections.

Using Eq. 5.56 the already discussed effect of the orientation in the morphology of plastics on stress crack resistance can be interpreted in the context of the particle model (Menges and RieB 1974). The size of structural particles (spherulites) in the partially crystalline thermoplastic geomembrane depends not only on the constitution of the polymer, but also on the conditions of the manufacturing process. Orientation makes the... 

The analysis of oriented morphologies resulting from polymer processing was already mentioned above. In addition to the characterization of the fibrillar... 

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