Drawing, Orientation and Texturing
category
Drawing of polyester yarn (POY or UDY) induces molecular orientation and crystallinity, transforming amorphous as-spun yarn into high-tenacity fully drawn yarn. False-twist texturing of POY produces textured yarn (DTY) with bulk, stretch, and cover. Drawing conditions (draw ratio, temperature, speed) determine final structure and mechanical properties.
Role
Drawing and texturing are the key structure-forming steps in polyester fibre production, directly controlling the mechanical properties, elastic recovery, and texture of the final yarn. Understanding these processes is central to fibre physics and textile engineering curricula.
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Subtopics
- Draw Ratio and Natural Draw Ratio Draw ratio (DR) = output speed / input speed, typically 3.5–5.5× for polyester. Natural draw ratio (…
- Hot Drawing and Heat-Setting Mechanisms Drawing above Tg (>67°C) allows chain segment mobility for orientation. Hot-pin or heated plate draw…
- False-Twist Texturing (DTY Process) False-twist texturing (FTT) draws POY through a heater (180–220°C, H1), a false-twist spindle (frict…
- Air-Jet Texturing and Taslan Process Air-jet texturing (Taslan® process) passes FDY through a supersonic air-jet nozzle at 0.4–0.6 MPa, c…
- Molecular Orientation and Birefringence Birefringence (Δn = n∥ − n⊥) quantifies optical anisotropy arising from molecular orientation. Measu…
- Crystallinity, Crystal Structure and Measurement PET crystallises in triclinic unit cell (a=4.56, b=5.94, c=10.75 Å, α=98.5°, β=118°, γ=112°). Crysta…
- Thermal Transitions: Tg, Tc, Tm PET thermal transitions by DSC: glass transition Tg ~67°C (amorphous PET), 80–90°C (oriented/crystal…
- Shrinkage, Residual Stress and Relaxation Polyester shrinkage arises from relaxation of oriented amorphous chains above Tg. Boiling water shri…
- Spin-Draw (One-Step) FDY Process One-step spin-draw combines melt spinning and drawing in a single machine: melt extruded at 280–290°…
- Draw-Texturing Defects and Quality Control Common DTY defects: tight spots (broken filaments winding around yarn, raised friction), broken fila…