Polyester Fiber (Synthetic / PET)
Polyester (PET) is the world's most produced textile fiber — 78 million tons in 2024, accounting for over 55% of global fiber output. It is a melt-spun synthetic fiber made from polyethylene terephthalate, prized for high strength, excellent dimensional stability, wrinkle resistance, and low cost. Its dominant position makes it the default choice for a vast range of apparel, home textile, and industrial yarn applications.
Quick Facts
| Type | Synthetic (melt-spun from petroleum-based polymer) |
| Chemical name | Polyethylene terephthalate (PET); 聚对苯二甲酸乙二酯 |
| Invented / commercialized | 1941 (Whinfield & Dickson, UK) / 1953 (DuPont: Dacron) |
| Global production (2024) | 78 million tons — virgin PET: ~69 Mt (88%); recycled rPET: ~9 Mt (12%) |
| Market share | ~55% of all global fiber production |
| China share of production | ~77% of world polyester output |
| Density | 1.38–1.40 g/cm³ |
| Moisture regain | 0.4% (standard); extremely hydrophobic |
| Melting point | 255–265°C (softens ~230–240°C) |
| Glass transition (Tg) | ~70–80°C (dry); ~65–70°C (wet) |
| Heat setting | Excellent; permanent set at 180–220°C |
| Key trade names | Dacron (DuPont), Terylene (ICI), Trevira, Coolmax, Thermolite |
Classification
By Form
| Form | Typical use | Key characteristics |
|---|
| Staple fiber (短纤) | Blended yarns (polyester/cotton, polyester/wool); nonwovens; filling | Cut to cotton-type (38 mm), wool-type (64–114 mm), or mid-length (51–76 mm); spun on cotton or wool systems |
| Filament yarn (长丝) | Apparel, sportswear, linings, industrial fabrics | Continuous; can be used directly or textured; ~65% of polyester production |
| Textured yarn (变形丝, DTY) | Knitwear, outerwear, stretch fabrics | False-twist textured for bulk, stretch, wool-like or cotton-like hand |
| POY / FDY | Draw-texturing feed (POY); direct-use flat yarn (FDY) | Partially oriented yarn (POY) → DTY; fully drawn yarn (FDY) → direct weaving/knitting |
| Microfiber (超细纤维) | Luxury apparel, cleaning cloths, synthetic leather | <0.9 dtex per filament; ultra-soft; high surface area |
| Hollow fiber (中空纤维) | Filling, insulation, thermal wear | Trapped air for warmth; lightweight |
By Chemical Variant
| Type | Full name | Differentiator |
|---|
| PET | Polyethylene terephthalate (涤纶) | Standard; >95% of polyester production |
| PTT (涤纶3 / PTT) | Polytrimethylene terephthalate | Better elastic recovery; softer drape; branded as Sorona® (DuPont) |
| PBT (涤纶4 / PBT) | Polybutylene terephthalate | Higher elasticity; better dyeability at boil; used in elastic textiles |
| rPET | Recycled polyester (再生涤纶) | From post-consumer PET bottles; 59% less energy than virgin; 9.3 Mt in 2024 |
By Modification (差别化涤纶)
| Modification type | What changes | Why it matters |
|---|
| Cationic-dyeable (CDP) | Sulfonated co-monomer enables cationic dye uptake | Solves polyester's dyeability problem; brighter colors, lower dyeing temperature |
| Easy-cationic (ECDP) | Atmospheric-pressure cationic dyeable | Dyeable at 100°C without carrier; further reduces energy and cost |
| Hydrophilic / moisture-management | Modified cross-section + surface treatment → wicking | Coolmax®-type: capillary channels transport moisture; solves the "clammy polyester" problem |
| Flame-retardant | Phosphorus-based comonomer or additive | LOI 28–32%; used in protective clothing, curtains, upholstery |
| Anti-pilling | Lower molecular weight surface layer | Reduced fiber strength at surface → pills break off before forming visible balls |
| Anti-static / conductive | Carbon or metal compound incorporation | Dissipates static charge; cleanroom garments, electronics industry |
| UV-resistant | TiO₂ or UV-absorber additives | Outdoor textiles, awnings, automotive interiors |
| Low-melt / binder fiber | Lower-Tm copolyester sheath | Thermally bonds nonwovens; core-sheath bicomponent |
Properties
| Property | Rating vs. cotton | Engineering implication |
|---|
| Tensile strength | ★★★★★ (higher than cotton) | 3.5–5.5 cN/dtex dry; strength retained when wet (no wet-strength loss unlike cotton's gain) |
| Elastic modulus | ★★★★★ (much higher) | High initial modulus → excellent dimensional stability, wrinkle resistance, shape retention |
| Elastic recovery | ★★★★☆ Good | Better than cotton; PTT/PBT variants improve further |
| Abrasion resistance | ★★★★☆ Good | Second only to nylon among common synthetics; good for activewear and outerwear |
| Moisture regain | ★☆☆☆☆ Very poor (0.4%) | Extremely hydrophobic; dries 3–5× faster than cotton but feels clammy against skin; requires moisture-management modification for comfort apparel |
| Dyeability | ★★☆☆☆ Poor (standard) | Disperse dyes only; requires high temperature (130°C) and pressure or carrier; CDP/ECDP modifications solve this |
| Heat setting | ★★★★★ Excellent | Best among common fibers; permanent crease/pleat retention; critical for wrinkle-free garments |
| Light / UV resistance | ★★★★☆ Good | Better than nylon, silk; behind acrylic; TiO₂ delustrant accelerates UV degradation unless stabilized |
| Chemical resistance | ★★★★★ Excellent | Resists organic solvents, soaps, bleaches, oxidizing agents, weak acids and alkalis; attacked by strong alkali at high temperature |
| Pilling tendency | ★★☆☆☆ High (standard) | High fiber strength + low moisture → pills form and DO NOT break off; anti-pilling variants reduce surface strength |
| Melt-drip behavior | ★★☆☆☆ Hazard | Melts at ~255°C; molten drips can cause severe burns; flame-retardant variants raise LOI but don't eliminate melting |
| Static electricity | ★★☆☆☆ Problematic | Low moisture → static buildup; anti-static modification or blending with hydrophilic fibers needed |
| Biodegradability | ★☆☆☆☆ None | 200+ years to degrade; microplastic shedding concern; rPET partially addresses resource issue but not end-of-life |
Advantages vs. Limitations
Advantages
- Exceptionally high strength and durability
- Excellent dimensional stability and wrinkle resistance
- Best heat-setting behavior among all fibers
- Resistant to most chemicals, bleaches, and solvents
- Quick-drying (3–5× faster than cotton)
- Blends well with cotton, wool, viscose, and other fibers
- Massive scale → lowest cost among synthetic fibers
- Recyclable via mechanical and chemical routes (rPET)
- Versatile: staple, filament, textured, microfiber, hollow, bicomponent
- Good light fastness (better than nylon and silk)
Limitations
- Extremely hydrophobic (0.4% regain) — clammy feel
- Difficult to dye (disperse dyes; high-temperature/pressure)
- Prone to pilling (pills do not break off due to high strength)
- Melts and drips when burning — safety hazard
- Static electricity buildup in dry conditions
- Non-biodegradable; microplastic pollution concern
- Fossil-fuel dependent (96% virgin production)
- Oleophilic — absorbs oil and grease stains
- Hand feel is more synthetic than natural fibers
- Low moisture regain → poor comfort in hot/humid conditions without modification
Yarn Engineering: Selection Guide
| Application | Recommended polyester type | Spinning system | Key criteria |
|---|
| Everyday apparel (polyester/cotton blends) | PET staple, 1.3–1.5 dtex, 38 mm | Ring or rotor; blended with cotton at carding | Fineness close to cotton; good blend uniformity; M ≥ 1.5 cotton preferred |
| Sportswear / activewear | PET textured filament (DTY); moisture-management cross-section | Direct filament knitting or texturing | Wicking channels; quick-dry; light weight; anti-odor optional |
| Sewing thread | PET high-tenacity filament or staple; core-spun | Ring (core-spun: PET core + cotton wrap) | Strength ≥ 5 cN/dtex; low shrinkage; good heat resistance for high-speed sewing |
| Shirting (wrinkle-free) | PET staple, 1.2–1.5 dtex, blended with cotton 65/35 or 50/50 | Ring or compact; combed cotton component | Dimensional stability; wrinkle recovery; acceptable hand feel at high polyester ratio |
| Outerwear / jackets | PET filament (FDY or DTY); possibly hollow fiber filling | Filament weaving + hollow-fiber filling | Wind resistance; insulation; durability; water-repellent finish |
| Carpets & upholstery | PET staple or BCF (bulked continuous filament) | Direct BCF or staple spinning | Abrasion resistance; stain resistance; colorfastness |
| Nonwovens (filtration, hygiene, geotextile) | PET staple; bicomponent low-melt sheath/core | Carded web → thermal bond or needle-punch | Fiber denier; cut length; thermal bonding temperature; chemical stability |
| Technical / industrial | PET high-tenacity filament (HT-PET) | Filament twisting / cabling | Strength ≥ 7 cN/dtex; low creep; UV-stabilized if outdoor; adhesion for coatings |
| Sustainable collections | rPET staple or filament (from bottle recycling) | Same as virgin PET; slightly lower tenacity | rPET tenacity ~5–10% lower than virgin; color consistency; GRS certification |
| Elastic / comfort-stretch | PTT or PBT filament; or PET + elastane core-spun | Ring core-spun or filament co-texturing | PTT: softer stretch, recovery ~80%; PBT: elastic, dyeable at boil; no elastane needed |
Modified Polyester Quick Reference
| Commercial name | Technology | Key benefit |
|---|
| Coolmax® (Invista) | Profiled cross-section (tetra-channel or similar) for capillary wicking | Moisture transport; keeps skin dry during activity |
| Thermolite® (Invista) | Hollow-core fiber; engineered air trapping | Lightweight warmth without bulk |
| Sorona® (DuPont / CovationBio) | PTT (37% bio-based 1,3-propanediol from corn) | Soft stretch, recovery, lower processing temperature |
| Dacron® (DuPont, original) | PET staple and filament; various cross-sections | Original polyester brand; now genericized |
| Trevira® | PET filament and staple; FR, antimicrobial, and sustainable variants | Flame-retardant PET for contract textiles; automotive |
| Repreve® (Unifi) | rPET from post-consumer bottles; traceable supply chain | Largest rPET brand; U-TRUST certification for recycled content verification |
| PrimaLoft® | Ultra-fine PET microfiber; mimics down | Insulation; water-resistant; used in outdoor gear |
| ECDP / CDP | Sulfonated co-monomer for cationic dyeability | Lower dyeing temperature; brighter colors; blends with wool at lower dye temps |
Comparison: Polyester vs. Key Competitors
| Property | PET Polyester | Cotton | Nylon 6 | Nylon 66 |
|---|
| Strength (cN/dtex) | 3.5–5.5 (dry & wet similar) | 2.5–4.5 (wet ↑10–20%) | 3.5–5.5 | 4.0–6.0 |
| Moisture regain (%) | 0.4 | 7–8.5 | 3.5–5.0 | 3.5–5.0 |
| Density (g/cm³) | 1.38 | 1.54 | 1.14 | 1.14 |
| Melting point (°C) | 255–265 | Decomposes ~150 | 215–225 | 255–265 |
| Elastic recovery | Good | Poor | Excellent | Excellent |
| Abrasion resistance | Good | Moderate | Excellent (best) | Excellent |
| Heat setting | Excellent | N/A | Moderate | Good |
| Dyeability | Difficult (disperse only) | Easy (many classes) | Easy (acid, disperse) | Easy |
| Cost (relative) | ★☆☆☆☆ (lowest) | ★★★☆☆ | ★★☆☆☆ | ★★☆☆☆ |
| Production scale (Mt) | 78 | ~25 | ~5.5 | ~5.5 (combined PA) |
Summary
Polyester is the workhorse fiber of the global textile industry. Its combination of high strength, excellent dimensional stability, heat settability, chemical resistance, and low cost makes it the default choice across apparel, home textiles, and industrial applications. Its main weaknesses — hydrophobicity, poor dyeability, pilling, and fossil-fuel dependence — are addressed by an extensive ecosystem of modifications (CDP, hydrophilic, FR, anti-pilling) and the growing rPET recycling infrastructure. For the yarn engineer, polyester selection is about matching the right form (staple vs. filament vs. textured), modification (standard vs. CDP vs. hydrophilic vs. FR), and blend ratio to the intended yarn structure and end use. See the Textile Material framework for substance–form–performance logic.