Mechanical properties of cellulose electro-active paper under different environmentalconditions

Abstract

The mechanical properties of cellulose-based electro-active paper (EAPap) areinvestigated under various environmental conditions. Cellulose EAPap has beendiscovered as a smart material that can be used as both sensor and actuator. Itsadvantages include low voltage operation, light weight, low power consumption,biodegradability and low cost. EAPap is made with cellulose paper coated withthin electrodes. EAPap shows a reversible and reproducible bending movementas well as longitudinal displacement under an electric field. However, EAPapis a complex anisotropic material which has not been fully characterized. Thisstudy investigates the mechanical properties of cellulose-based EAPap, includingYoung’s modulus, yield strength, ultimate strength and creep, along with orientationdirections, humidity and temperature levels. To test the materials in different humidityand temperature levels, a special material testing system was made that cancontrol the testing environmental conditions. The initial Young’s modulus ofEAPap is in the range of 4–9 GPa, which was higher than that of other polymermaterials. Also, the Young’s modulus is orientation dependent, which may beassociated with the piezoelectricity of EAPap materials. The elastic strength andstiffness gradually decreased when the humidity and temperature were increased.Creep and relaxation were observed under constant stress and strain, respectively.Through scanning electron microscopy, EAPap is shown to exhibit both layered andoriented cellulose macromolecular structures that impact both the elastic and plasticbehavior.