Coiled and non-coiled twisted polymer fiber torsional and tensile actuators

A process comprising:

• (a) selecting a high-strength, highly-chain-oriented, precursor polymer fiber, wherein the precursor polymer fiber is single-filament or multi-filament;
• (b) inserting twist by a twisting method to form a coiled polymer fiber, wherein the twisting method is selected from the group consisting of
• (1) inserting sufficient twist into the precursor polymer fiber to produce coiling while the precursor polymer fiber is under applied tensile mechanical load,
• (2) inserting twist into a precursor polymer fiber that is too low to produce coiling under the applied tensile mechanical load, and subsequently wrapping the resulting non-coiled polymer fiber around a mandrel, and
• (3) combinations thereof;
• and
• (c) tethering the coiled polymer fiber to prevent irreversible loss of twist for use as a thermally-powered coiled polymer fiber tensile actuating element in a thermally-powered coiled polymer fiber tensile actuator system.

A process comprising:

• (a) selecting a single-filament or multifilament, high strength, highly-chain-oriented, precursor polymer fiber;
• (b) applying a twisting method to the precursor polymer fiber to form a twisted polymer fiber, wherein the twisting method is selected from a group consisting of:
• (1) inserting twist into the precursor polymer fiber, wherein the inserted twist is below the twist needed to produce coiling of the precursor polymer fiber,
• (2) inserting twist into the precursor polymer fiber until coiling occurs,
• (3) inserting twist into the precursor polymer fiber until coiling occurs along substantially the entire fiber length,
• (4) inserting twist in the same direction into the precursor polymer fiber and a at least one other precursor polymer fiber and then plying these at least two twisted polymer fibers together to make a multi-ply fiber by using an opposite direction for plying than for the inserted twist;
• (c) tethering the twisted-polymer fiber to prevent irreversible loss of twist for use as a thermally-powered polymer torsional actuating element in a thermally-powered polymer fiber torsional actuator system.

A thermally-powered polymer fiber torsional actuator comprising a twisted, chain-oriented polymer fiber, wherein

• (a) the thermally-powered polymer fiber torsional actuator has a first degree of twist at a first temperature at an applied torque;
• (b) the thermally-powered polymer fiber torsional actuator has a second degree of twist at a second temperature at the applied torque;
• (c) the first degree of twist and the second degree of twist are different in degree of twist by at least 0.5%;
• (d) the thermally-powered polymer fiber torsional actuator is operable to reversibly change back and forth between the first degree of twist and the second degree of twist by changing temperature between the first temperature and the second temperature at the applied torque;
• and
• (e) the thermally-powered polymer fiber torsional actuator is a thermally-powered, non-electrochemical polymer fiber torsional actuator.

A thermally-powered coiled polymer fiber actuator comprising a twisted, chain-oriented polymer fiber in the shape of a coil, wherein

• (a) the coil has a first chirality, and
• (b) the twisted fiber has a second chirality, wherein
• (i) the first chirality and the second chirality are opposite and the thermally-powered coiled polymer fiber actuator is operable to increase length when heated, or
• (ii) the first chirality and the second chirality are the same and the thermally-powered coiled polymer fiber actuator is operable to increase stiffness when heated to a temperature in a temperature range while applying a load in a load range.