Artificial muscles based on coiled UHMWPE fibers with shape memory effect

Abstract

Ultra-high molecular weight polyethylene (UHMWPE) fibers drawn at drawing ratio of 6 (pre-deformation strain 500%) demonstrating the obtained one-way shape memory effect. Artificial muscles have been manufactured in the form of coiled UHMWPE fibers. Isometric recovery stress and recovery strain of the fibers were measured during heating by using a dynamic mechanical analyzer (DMA). As a result, the fibers were capable to demonstrate large contraction of 78% (recovery strain of 93%) due to the entropic elasticity. The recovery stresses of the fibers reach up to 27 MPa. The work of stroke cycle for coiled artificial muscles with a constant stress of 1 MPa was recorded. Artificial muscles based on coiled UHMWPE fibers have a large stroke of 64 %. The structural mechanisms of muscle-like behavior were discussed.

Keywords

• Smart polymers
• UHMWPE
• Artificial muscles
• recovery stress
• stroke