Polyethylene terephthalate orthorhombic symmetry

Table 7. Full Set of Compliances for the Oriented Polyethylene Terephthalate Sheet with Orthorhombic Symmetry...

Similar isochronous studies have been carried out on polyethylene terephthalate sheets with orthorhombic symmetry by Ladizesky and Ward, on cold-drawn Nylon 6 and 66 by Owen and Ward and on oriented polypropylene by Owen and Ward. ... 

Oriented Polyethylene Terephthalate Sheet with Orthorhombic Symmetry... 

All nine independent elastic constants have been determined for one-way drawn oriented polyethylene terephthalate sheet. The sheet was prepared by drawing isotropic sheet at constant width. It has been shown that there is then both a high degree of chain orientation in the draw direction and that the (100) crystal planes (which mainly reflect preferential orientation of the terephthalate residues in the chain) are preferentially oriented in the plane of the sheet. This type of orientation has been termed uniplanar axial. From the viewpoint of elastic anisotropy, the sheet possesses three orthogonal planes of symmetry and can be described as possessing orthorhombic symmetry. 

Table 8.9 Full set of compliances for the oriented polyethylene terephthalate sheet with orthorhombic symmetry [18].

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