Experimental determination of the elastic modulus of crystalline regions in oriented polymers

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 × 10 4 kg./cm. 2 ; polyethylene, 240 × 10 4 kg./cm. 2 ; polypropylene, 42 × 10 4 kg./cm. 2 ; polyoxymethylene, 54 × 10 4 kg./cm. 2 ; cellulose, 137 × 10 4 kg./cm. 2 ; polyvinylidene chloride, 41.5 × 10 4 kg./cm. 2 .