Determining surface tension of various liquids and shear modulus of paper using crumpling effect
(1) Kendriya Vidyalaya No.1 AFS Kalaikunda, West Bengal, India , (2) Air Force Golden Jubilee Institute, New Delhi, India
When a wet piece of paper is dried, it becomes crumpled. We termed this phenomenon the ‘Crumpling Effect’. The crumpling effect is commonly referred to as buckling of paper by water-color artists and can be caused by water or various other liquids and solutions. We hypothesized that the surface tension of the liquid soaked in the paper acts parallelly to the plane of the sheet but perpendicularly on the paper fibers as shear stress. The shear stress of surface tension pulls the sheet inwards as an attempt by the liquid to reduce its surface energy and creates the crumpling in the sheet of paper. We experimented with different liquids and observed that the mean height of crumpling varied by liquid with an ink solution causing the greatest crumpling 0.0028 m and a soap solution causing the least crumpling of 0.0008 m. Crumpling Effect measurements can be used to determine the surface tension of any liquid absorbed by paper. However, the shear modulus of elasticity of paper is not standard and depends on the quality of materials and method of manufacture. By repeating the experiment with purified water and different paper qualities, we determined the shear modulus of the papers to be 0.043 N/m for copier paper and 0.015 N/m for bond paper.
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