Mapping the geometry dependent relative stress in stretched polymer membranes by polarization and interferometric techniques

This paper reports experimental results on contactless geometry dependent stress characterisation and mapping in elastic polymer membranes using polarization and interferometric techniques. Three different geometries of polydimethylsiloxane (PDMS) namely, rectangular, wedge and bowtie shaped membranes are studied. The membranes were initially stretched and then relaxed from one edge during the characterisation. In the rectangular membrane the stress was observed to be concentrated at the static edge of the membrane. Whereas, in the wedge and bowtie shaped membranes, the stress is found to be concentrated at the locations wherein the membrane has a narrower width. The proposed facile methods for characterisation are helpful in designing stress induced tuneable optics and to analyze stress in polymer membranes during their industrial production.