Experimental Determination of Elastic Moduli of the Crystalline Regions in Oriented Polymers

Abstract

The elastic modulus of the crystalline regions in some oriented polymers was determined. An x-ray diffractometer specially constructed for this purpose was used, and the lattice extension in the direction of the fiber axis was measured under application of a direct load. Usually a meridional reflection was used for the measurement of the lattice extension, but in the case where no strong meridional reflection exists a reflection from planes which are almost perpendicular to the fiber axis of the crystallites was used. The elastic modulus was calculated under the assumption of a simple series model. The values found are as follows: polyvinyl alcohol, 255 104 kg./cm.2; polyethylene, 240 104 kg./cm.2; polypropylene, 42 104 kg./cm.2; polyoxymethylene, 54 104 kg./cm.2; cellulose, 137 104 kg./cm.2; polyvinylidene chloride, 41.5 104 kg./cm.2.