PBAT (Polybutylene Adipate Terephthalate)
Quick Overview
PBAT is a biodegradable copolyester that combines flexibility with compostability.
What Is PBAT?
Polybutylene Adipate Terephthalate (PBAT) is a flexible, biodegradable copolyester that has become an essential enabling material for the compostable plastics industry. While less well-known to consumers than PLA or PHA, PBAT plays an indispensable role as the flexibility provider in compostable blends.
PLA is stiff and brittle. Starch is water-sensitive and weak. PBAT adds the elongation, tear resistance, and processability that these materials lack — enabling practical compostable bags, films, and packaging.
Chemical Structure
PBAT is a random copolymer of:
- Butylene adipate (soft, flexible segments)
- Butylene terephthalate (hard, crystalline segments)
The ratio determines the final properties. Higher adipate content yields softer, more flexible polymers; higher terephthalate increases stiffness.
PBAT Properties
| Property | PBAT | PLA (for comparison) | LDPE (for comparison) |
|---|---|---|---|
| Tensile strength | 15–35 MPa | 50–70 MPa | 10–25 MPa |
| Elongation at break | 400–800% | 3–8% | 200–600% |
| Melting point | 110–120°C | 150–180°C | 105–115°C |
| Glass transition | -30°C | 55–65°C | -120°C |
| Compostable | Yes (EN 13432) | Yes (with PBAT) | No |
| Typical use | Blending component | Rigid items | Films, bags |
Key Applications
Starch/PBAT vs. PLA/PBAT
| Property | Starch/PBAT (50:50) | PLA/PBAT (70:30) |
|---|---|---|
| Cost | Lower (~0.7x PLA/PBAT) | Higher |
| Tensile strength | 10–20 MPa | 30–40 MPa |
| Flexibility | High | Moderate |
| Water resistance | Lower (starch is hydrophilic) | Higher |
| Compostable | Yes (EN 13432) | Yes (EN 13432) |
| Bio-based content | 40–60% | 70–80% |
| Typical uses | Bags, mulch films, loose-fill | Flexible packaging, food service |
| Typical ratio | 30–60% starch / 40–70% PBAT | 70–80% PLA / 20–30% PBAT |
Paper Coatings
- Compostable paper cups and plates
- Food packaging barrier coatings
- PBAT provides moisture barrier and heat sealability
Major Producers
| Producer | Brand | Capacity (approx.) |
|---|---|---|
| BASF | Ecoflex® | ~75,000 t/year |
| Novamont | Origo-Bi® | ~50,000 t/year |
| Eastman | Eastar Bio | ~25,000 t/year |
| Kingfa | ECOPOND | Growing |
| Jinhui Zhaolong | ECWORD | Growing |
Biodegradation
- Industrial composting (58°C): 90–180 days, fully EN 13432 certified
- Ambient soil: 6–24 months
- Marine: Does not biodegrade readily
- PBAT requires industrial composting to deliver its end-of-life benefit
Frequently Asked Questions
Is PBAT made from petroleum? Most commercial PBAT is petroleum-derived (from fossil-based adipic acid and butanediol). Bio-based PBAT routes are emerging but not yet dominant.
Can PBAT be used alone? Rarely. Its low tensile strength and thermal stability mean it performs best as a blend component with PLA or starch.
Is PBAT certified compostable? Yes. PBAT is certified to EN 13432, ASTM D6400, and carries OK Compost certification.
How does PBAT cost compare to PBAT alternatives? PBAT costs approximately 1.5–3× conventional PE. It is generally less expensive than PHA, making it the preferred flexible compostable polymer.
Related Terms
- PLA — The polymer PBAT is most commonly blended with
- Bioplastic Blends — PBAT’s primary application context
- Compostable — The certification standard PBAT meets
- EN 13432 — The key compostability standard
- Starch-based Bioplastic — Another common PBAT blend partner
Standards & Certifications
- EN 13432 (Industrial Compostable)
- ASTM D6400
- OK Compost certification
Major Producers
- BASF (Ecoflex)
- Novamont (Origo-Bi)
- Eastman
- Kingfa
- Jinhui Zhaolong
Key Applications
- Flexible films
- Compostable bags
- Agricultural mulch films
- Food packaging
- Coating for paper products