Experimental Set for Studying Mechanical Property of Polymer Through Light Diffraction

This research aims to design and construct an experimental set for investigating the mechanical property of a plastic bag via diffraction experiment. The plastic bag sample was cut into 15 cm × 2.5 cm following the standard test method ASTM D882, and then stretched with various weights providing a tensile force. During stretching, the changing length of a plastic sample at any weight was real-time recorded using a VDO camera and the diffraction patterns of light with a wavelength of 532 nm through stretched plastic bag was taken simultaneously. The tensile stress-strain curve obtained using the Tracker software could be used to calculate the Young's modulus of sample, whereas the diffraction patterns could be observed after ending elastic region due to forming empty space or slits in plastic resulting from tensile forces. The experimental set proposed herein could be used for demonstration of the diffraction of light and mechanical property of material in physics teaching.