The mechanical properties of cellulose-based electro-active paper (EAPap) are investigated under various environmental conditions. Cellulose EAPap has been discovered as a smart material that can be used as both sensor and actuator. Its advantages include low voltage operation, light weight, low power consumption, biodegradability and low cost. EAPap is made with cellulose paper coated with thin electrodes. EAPap shows a reversible and reproducible bending movement as well as longitudinal displacement under an electric field. However, EAPap is a complex anisotropic material which has not been fully characterized. This study investigates the mechanical properties of cellulose-based EAPap, including Young's modulus, yield strength, ultimate strength and creep, along with orientation directions, humidity and temperature levels. To test the materials in different humidity and temperature levels, a special material testing system was made that can control the testing environmental conditions. The initial Young's modulus of EAPap is in the range of 4-9 GPa, which was higher than that of other polymer materials. Also, the Young's modulus is orientation dependent, which may be associated with the piezoelectricity of EAPap materials. The elastic strength and stiffness 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 and oriented cellulose macromolecular structures that impact both the elastic and plastic behavior.

The effective coefficient of thermal expansion is derived for fiber com posites in two dimensional quasi-isotropic form and three-dimensional isotropic form. These systems represent constructions that have fibers ran domly oriented in a plane and in three dimensions. The effective coeffi cients of thermal expansion are related to the thermal-mechanical proper ties of individual fiber and matrix phases. These results are put into asymp totic forms appropriate to very stiff fiber systems. The asymptotic predic tions are evaluated against the complete forms, and both results are com pared with an experimental result.

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Mechanical properties of cellulose-based electro-active paper (EAPap) are characterized in this work. Cellulose-based EAPap has been studied as a potential actuator concept, as a result of its low actuation voltage, lightweight, low power consumption, biodegradability and low cost. EAPap is made from cellulose paper, coated with thin electrically conducting electrodes. This EAPap shows a reversible and reproducible bending movement as well as a longitudinal displacement under electric field excitation. However, the EAPap is a complex anisotropic material, which has not been extensively characterized. It is important to have extended property data for EAPap so that the actuator performance can be optimized, and this requires additional material testing. Our material test results show that EAPap has two distinct elastic constants. The initial Young's modulus of EAPap is in the range of 4–9 GPa, which is higher than other polymer materials. This modulus is also orientation dependent, which may be associated with the piezoelectricity of the EAPap materials. Another important property is that the dynamically induced mechanical strains of these materials exhibit linear creep behaviour as confirmed by constant stress and low frequency cyclic loading tests. From scanning electron microscope investigations, cellulose EAPap exhibits a layered, anisotropic cellulose macromolecular structure that exhibits both elastic and plastic deformations, as well as substantial temperature and humidity dependence.

In this short work of 1860, William Craft (c.1825–1900), assisted by his wife Ellen (c.1825–91), recounts the remarkable story of how they escaped from slavery in America. Having married as slaves in Georgia, yet unwilling to raise a family in servitude, the couple came up with a plan to disguise the light-skinned Ellen as a man, with William acting as her slave, and to travel to the north in late 1848. This compelling narrative traces their successful journey to Philadelphia and their subsequent move to Boston, where they became involved in abolitionist activities. Later, the couple sought greater safety in England, where they lived for a number of years and had five children. A success upon its first appearance, the book touches on the themes of race, gender and class in mid-nineteenth-century America, offering modern readers a first-hand account of how barriers to freedom could be overcome.