Introduction to Thermoforming Plastics
Thermoforming is one of the most widely used methods for producing packaging trays, blisters, clamshells, and medical devices. Among the many materials available, PET (Polyethylene Terephthalate), PETG (Polyethylene Terephthalate Glycol-modified), and GAG (Glycol-modified Amorphous Copolyester, often PET/ PETG laminate) are the three most popular for clear, rigid packaging.
Each material offers unique benefits in terms of clarity, formability, impact resistance, and cost. Choosing the right one depends on your application, budget, and performance requirements.
What is PET?
PET (Polyethylene Terephthalate) is a strong, transparent thermoplastic commonly used for packaging food, beverages, and consumer goods.
- Key Properties: Excellent clarity, strong barrier against moisture, cost-effective.
- Advantages: Food-safe, widely available, recyclable (RPET options).
- Limitations: Lower impact resistance compared to PETG; limited deep-draw thermoforming ability.
What is PETG?
PETG (Polyethylene Terephthalate Glycol-modified) is a modified form of PET with glycol added during polymerization. This prevents crystallization, making the material more ductile and easier to thermoform.
- Key Properties: Superior impact resistance, easy to thermoform at lower temperatures, can be sterilized.
- Advantages: Crack-resistant, suitable for deep draws, excellent chemical resistance, safe for medical packaging.
- Limitations: Higher cost than standard PET; may scratch more easily.
What is GAG?
GAG (PET / PETG laminate sheet) combines PET layers with a PETG core. This gives the sheet a balance of cost-efficiency and formability.
- Key Properties: Surface hardness and chemical resistance from PET; flexibility and impact strength from PETG.
- Advantages: Balanced cost and performance; good for blister packaging.
- Limitations: Not as clear as pure PET; limited recyclability compared with single-material sheets.
Comparison Table: PET vs PETG vs GAG
| Property / Feature | PET | PETG | GAG |
|---|---|---|---|
| Clarity | Excellent | Excellent | Good (slightly less than PET) |
| Impact Resistance | Moderate | High | Medium-High |
| Thermoformability | Limited deep draw | Excellent, low-temp forming | Good |
| Cost | Low | Higher | Medium |
| Food Safety | Yes | Yes | Yes |
| Recyclability | Excellent (RPET options) | Recyclable but less common | Limited due to layered structure |
| Applications | Food trays, RPET packaging | Medical trays, electronics, luxury packaging | Blister packs, foldable boxes |
Applications in Thermoforming
PET
- Food packaging trays and lids
- Blister packs for consumer goods
- Clamshell packaging
- Environmentally friendly RPET solutions
PETG
- Medical device packaging (sterile barrier)
- Electronics packaging (anti-shock)
- Cosmetic and luxury boxes
- Deep-draw thermoformed parts
GAG
- Blister cards and folding boxes
- Low- to medium-cost retail packaging
- Products requiring balance between cost and strength
Key Advantages Summary
- PET → Best for cost efficiency and recyclability.
- PETG → Best for performance, flexibility, and deep draws.
- GAG → Best for balanced cost-performance in blister packaging.
Choosing the Right Material
When selecting a thermoforming plastic sheet:
- Consider your application – Food, medical, or consumer goods?
- Evaluate formability needs – Deep draw vs shallow trays.
- Check budget vs performance – PET is cheapest, PETG is premium, GAG is in-between.
- Think about sustainability – PET and RPET are more recycling-friendly.
Conclusion
PET, PETG, and GAG each serve unique roles in the thermoforming industry. While PET offers cost savings and recyclability, PETG stands out for performance and medical-grade packaging. GAG provides a balanced option for blister packaging where cost and performance need to be optimized.
Choosing the right sheet requires balancing clarity, impact resistance, formability, and sustainability goals.
FAQ
Is PET or PETG better for thermoforming?
Both PET and PETG are widely used in thermoforming, but the choice depends on the application. PET is more cost-effective and has excellent clarity, making it ideal for food trays and blister packaging. PETG, however, is more impact-resistant and flexible, making it better suited for medical packaging, electronics, and products requiring deeper draws.
What is the difference between PETG and GAG sheets?
The main difference lies in structure. PETG is a single modified polymer with glycol, offering superior toughness and formability. GAG is a laminate sheet (PET outer layers with a PETG core), giving it good balance between cost and performance. GAG is often used in blister packs and folding boxes, while PETG is preferred for high-performance or medical applications.
Is GAG recyclable like PET?
GAG is less recyclable compared with pure PET or PETG, because it is a multi-layered laminate. Recycling facilities often prefer single-material streams. For brands with strict sustainability goals, PET or RPET (Recycled PET) is the better choice.
Which is more impact-resistant, PET or PETG?
PETG is significantly more impact-resistant than PET. It is less likely to crack under pressure, making it the material of choice for deep-draw thermoforming or products that require strong handling. PET, while clear and rigid, is more brittle compared to PETG.
What are the typical applications of PET vs PETG vs GAG?
- PET: Food trays, beverage packaging, clamshells, RPET eco-packaging.
- PETG: Medical trays, electronics packaging, cosmetic boxes, luxury packaging.
- GAG: Blister cards, folding cartons, cost-sensitive retail packaging.
Which thermoforming sheet is most cost-effective?
For large-scale, cost-sensitive projects, PET is usually the most economical. GAG offers a mid-range cost option, while PETG is more expensive but provides added performance and durability.
Can PETG and PET be used together in packaging?
Yes. Some packaging solutions combine PET outer layers for clarity and PETG components for flexibility and impact resistance. This hybrid approach is especially common in medical and cosmetic packaging.
