In order to generate the bending motion operated by pressure change in hydrogen gas, soft uni-morph composites were prepared, in which composites dispersed with not only driving particles of LaNi 5 hydrogen storage alloy with Pd-Al 2 O 3 catalyst powders to get high responsiveness, were piled up on a simple polyurethane sheet. Since the highest values of irreversible bending strain at the first hydrogenation (" 1) under 0.3 MPa H 2 gas and the maximum irreversible bending strain during hydrogenation cycles (" m) were remarkably obtained at the 35 vol% of LaNi 5 powders dispersed in polyurethane composites, the bending strain of reversible motion was detected from the first to the 8th hydrogenation (" r 1 and " r 8) under 0.2 MPa H 2 gas. The bending strain of reversible motion of polyurethane composites sheet is more than 2000 ppm, which was approximately equal to that of silicone rubber composites and is extremely larger than that (300 ppm) of ABS resin composites. Responsiveness (d"=dt) of cyclic motion of elastic deformed mover composites, which were constructed with 35 vol%LaNi 5 dispersed powder and matrix of polyurethane or silicone rubber, were more than 10 times higher than that of ABS composite.

The polyurethane composites dispersed with powders mixture of LaNi 5 hydrogen storage alloy (35 vol% of LaNi 5 ) and Pd-Al 2 O 3 catalyst powders were prepared by solution cast method, which easily controlled the shape and mixed ratio of the composites. In order to generate the bending strain of reversible up motions at vertical and horizontal directions, the unimorph (PU+LaNi 5 /Cu) sheet constructed with the driving polyurethane composite and supporting copper thin sheet of 10 mm thickness with high specific stiffness (apparent hardening modulus per specific weight) was prepared.Although the bending motion of the unimorph sheet operated by hydrogenation under 0.3 MPa H 2 gas was irreversible, the reversible motion was detected under 0.2 MPa H 2 gas. The maximum strain of reversible bending motion (" max ) of the PU+LaNi 5 /Cu sheet is more than 1520 and 1120 ppm on vertical and horizontal directions, respectively. The " max of the PU+LaNi 5 /Cu sheet at vertical direction was slightly higher than that of the ABS resin unimorph (ABS+LaNi 5 /ABS) sheet constructed with the driving ABS resin composites and pure ABS resin supporting sheet, whereas it was slightly lower than that of the silicone rubber unimorph (SR+LaNi 5 /SR) sheet constructed with the driving silicone rubber composites and pure silicone rubber supporting sheet. It can be estimated that the responsiveness (d"=dt) of cyclic motion of the (PU+LaNi 5 /Cu) sheet is slightly higher than ABS+LaNi 5 /ABS sheet.

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