Abstract
Artificial muscles from nylon 6 fibers have been widely studied for their low-cost, high-strength, light weight, and high performance. We investigate mechanical properties of nylon 6 artificial muscle including creep, stress relaxation, thermal actuation force, and tensile tests. Shape of nylon 6 artificial muscle can be fixed after annealing, and we apply four different annealing temperatures to study the influence of annealing temperature on mechanical properties. We use standard linear solid model to fit the creep and stress relaxation data, and the relaxation rate (βc and βS) satisfies the Arrhenius equation. The activation energy decreases with increasing annealing temperature. We also investigate the mechanical properties of nylon 6 non-twisted fibers and chicken muscle fibers to evaluate the influence of twist insertion and the difference between natural muscle and artificial muscle. In tensile tests, nylon 6 non-twisted fibers have largest Young’s modulus and chicken muscle fibers have the smallest. In creep tests, these three materials all follow standard linear model, and the relaxation rates (βc) satisfy the Arrhenius equation. Like nylon 6 artificial muscles, the activation energy in the creep test decreases with increasing annealing temperature for nylon 6 non-twisted fibers. The studies of crystallinity show that crystallinity increases with increasing annealing temperature. We discuss the influence of crystallinity on creep tests and stress relaxation.