Interpretation of mechanical anisotropy general considerations

The mechanical anisotropy of oriented polymers is determined by the following factors, which will be discussed in turn (1) the structure of the molecular chain and, where the polymer crystallises, the crystal structure (2) the molecular orientation and, in a crystalline polymer, the morphology (3) thermally activated relaxation processes in both crystalline and non-crystalline regions. [Pg.192]

Recent Brillouin spectroscopy measurements include those of Kumar, Renisch and Grimsditch [30] on uniaxially and biaxially stretched polypropylene films. Using the Ward aggregate model with a modified definition of molecular alignment enabled elastic anisotropy and refractive index data to be related quantitatively to molecular orientation. [Pg.139]