Structural Characterization of Isotactic Polypropylene Films of Ultrahigh Orientation. Part I. Determination of Crystalline and Amorphous Orientation.
ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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Preferred orientation of the crystalline and amorphous regions in semicrystalline polymers have long been recognized as important factors influencing physical and mechanical behavior. Nearly perfect crystalline orientation was found in a set of four polypropylene films prepared under different stretching conditions by X-ray diffraction. This demonstrates that neither shear nor pressure is essential to the attainment of ultrahigh crystalline orientation. Sonic modulus measurements give values from 0.38 to 0.69 for the amorphous orientation function. The results indicate that certain variations in structure are possible in polymers with ultrahigh crystalline orientation.
- Atomic and Molecular Physics and Spectroscopy