Polymer hydrogels can be used to produce smart actuators, constructed from lightly cross-linked polymer inhomogeneous networks that contain solvent. Gel actuators are able to change their stiffness with gel hydration, and as an effect of other parameters, such as pH, temperature, chemical composition, etc. In this work, Nisopropylacrylamide (NIPA) gels are mechanically characterised to possibly serve as actuating cylinders and fibres in braids with vibration-damping purposes. Mechanical properties are obtained at different hydration levels and for different cross-linking density, using N,N’-Methylenebisacrylamide (BIS) as crosslinker, and the effect of these two parameters is studied statistically. The results indicate that both the addition of crosslinker and gel hydration yield a quite predictable effect, not far from linearity, on the mechanical properties of NIPA gel, which is promising for their use in actuators upon a wide range of crosslinker content and water/gel ratio. In general, it is proposed that a 7:1 ratio water/gel, or slightly inferior, with the maximum possible amount of crosslinker that allows retaining the swelling/deswelling properties, would be optimal for the operation of the actuator.
Mechanical characterisation of n-isopropylacrylamide (NIPA) gels for use in smart actuators
SANTULLI, CARLO
2011-01-01
Abstract
Polymer hydrogels can be used to produce smart actuators, constructed from lightly cross-linked polymer inhomogeneous networks that contain solvent. Gel actuators are able to change their stiffness with gel hydration, and as an effect of other parameters, such as pH, temperature, chemical composition, etc. In this work, Nisopropylacrylamide (NIPA) gels are mechanically characterised to possibly serve as actuating cylinders and fibres in braids with vibration-damping purposes. Mechanical properties are obtained at different hydration levels and for different cross-linking density, using N,N’-Methylenebisacrylamide (BIS) as crosslinker, and the effect of these two parameters is studied statistically. The results indicate that both the addition of crosslinker and gel hydration yield a quite predictable effect, not far from linearity, on the mechanical properties of NIPA gel, which is promising for their use in actuators upon a wide range of crosslinker content and water/gel ratio. In general, it is proposed that a 7:1 ratio water/gel, or slightly inferior, with the maximum possible amount of crosslinker that allows retaining the swelling/deswelling properties, would be optimal for the operation of the actuator.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
