Shape-Memory Fibers
Functional / Stimulus-Responsive Form Recovery (SMF / 形状记忆纤维)
Quick Facts
| Type | Functional / smart fiber; returns to a pre-programmed permanent shape when exposed to a specific stimulus (heat, moisture, light, electric field) |
| Material types | Shape-memory alloys — NiTi (Nitinol), Cu-based, Fe-based: thermal trigger; Shape-memory polymers — polyurethane (SMPU), PTT/PET bicomponent, polystyrene, epoxy: thermal or moisture trigger; Shape-memory gels — PNIPAM, PVME: thermal swelling/collapse |
| Programming process | Fiber deformed at elevated temperature → cooled in deformed state (temporary shape fixed) → reheated above transition temperature → recovers original (permanent) shape |
| Key textile form | PTT/PET bicomponent side-by-side fiber (亚弹性纤维) — differential thermal shrinkage creates self-crimping with shape memory; the most commercially viable textile SMF form |
Properties
| Property | Rating | Engineering implication |
|---|---|---|
| Shape recovery | ★★★★★ | >95% recovery to original shape upon triggering; the defining smart-material property |
| Cycle life | ★★★★☆ | Hundreds to thousands of thermomechanical cycles; gradual degradation; adequate for durable textile applications |
| Trigger temperature | ★★★★☆ | Tunable via polymer chemistry (40–80°C typical for textile SMPU); body heat-triggered variants under development |
Applications
| Application | Form | Key criteria |
|---|---|---|
| Adaptive clothing | SMPU fiber or film; body heat-triggered | Garments that adjust fit, ventilation, or insulation with temperature; experimental/prototype stage |
| Self-crimping stretch yarns | PTT/PET bicomponent; permanent 3D crimp via thermal memory | Stretch fabrics without spandex; the only commercially mature SMF textile application |
| Medical devices | NiTi or SMPU fiber; stents, orthodontic wires, sutures | Self-expanding stents; shape-memory sutures that tighten with body heat; the most successful SMF application (non-textile) |
Summary
Shape-memory fibers are the closest textiles come to 'smart materials' — they remember and return to a programmed shape. Commercial textile applications are currently limited to self-crimping PTT/PET yarns, with adaptive clothing and medical devices as the frontier. See the Textile Material framework.