With increasing global environmental regulations and growing consumer demand for sustainable packaging, the plastics industry faces dual challenges: achieving degradability and recyclability.
Conventional PET (Polyethylene Terephthalate) remains the dominant material for beverage and edible oil bottles due to its excellent transparency, strength, and processability. However, standard PET is non-biodegradable and can take hundreds of years to decompose, raising environmental concerns.
As a result, researchers and manufacturers are now focusing on developing degradable or partially biodegradable PET materials that maintain performance while reducing environmental impact.
Partially Degradable PET (Modified PET)
This approach involves modifying traditional PET by adding biodegradable monomers or bio-based polyesters (such as PBS, PBAT, or PLA). The goal is to enhance biodegradability while retaining similar mechanical and processing properties.
1️ Bio-PET (Bio-based PET)
Bio-PET is produced using plant-derived monoethylene glycol (Bio-MEG) and purified terephthalic acid (PTA).
A well-known example is Coca-Cola’s PlantBottle™, made with up to 30% renewable plant-based content.
Advantages:
Fully compatible with existing PET blow molding lines
High transparency and mechanical strength comparable to virgin PET
Reduced carbon footprint, supporting carbon neutrality goals
Disadvantages:
Limited biodegradability (only under industrial composting conditions)
Higher raw material cost and limited supply chain availability
2️ RPET + Biodegradable Additives
Recycled PET (RPET) can be combined with bio-based modifiers or degradable additives to enhance eco-performance without sacrificing mechanical strength.
Suitable for preforms, films, and packaging applications
Highly compatible with existing PET production lines
Fully Biodegradable Alternatives (Non-PET Systems)
To achieve complete biodegradability, manufacturers must turn to non-PET polymers that can break down into carbon dioxide and water under composting or microbial conditions.
| Material | Features | Suitable as PET Bottle Replacement |
| PLA (Polylactic Acid) | Derived from corn or sugarcane; fully biodegradable | Usable for bottles but low heat resistance (≤60°C) |
| PHA (Polyhydroxyalkanoate) | Bio-synthesized polymer; fully degradable | Excellent biodegradability but high cost |
| PBS / PBAT blends | Flexible and biodegradable | Suitable for films, not for high-pressure bottle preforms |
⚠️ Note: These materials differ significantly from PET in heat resistance and mechanical strength, requiring specialized injection-blow molding equipment and molds.
Blow Molding Process Adjustments
When using degradable or modified PET resins, specific adjustments to the blow molding process are required to prevent thermal decomposition or poor molding quality:
1.Stricter drying requirements – moisture must be ≤30 ppm
2.Lower blow molding temperature – typically 10–20°C lower than standard PET
3.Longer cooling cycle – prevents thermal degradation
4.Precise mold temperature and air pressure control – ensures wall thickness uniformity and clarity
5.Application limitations – not suitable for hot-fill products or long-term beverage storage
Comparative Evaluation and Future Trends
| Objective | Recommended Material | Compatibility | Biodegradability | Cost | Market Outlook |
| Eco-friendly & compatible with PET lines | Bio-PET / Modified PET | ✅ High | ⚠️ Partial | Medium–High | Short-term mainstream |
| Fully biodegradable packaging | PLA / PHA | ❌ Requires new line | ✅ Excellent | High | Mid–long term trend |
Future development will focus on two key directions:
1.Increasing the proportion of bio-based content to reduce fossil fuel dependency.
2.Creating dual-function PET materials that are both recyclable and partially degradable, supporting circular economy initiatives.
Conclusion
For manufacturers who want to retain existing PET production lines, Bio-PET or modified PET provides an environmentally friendly yet practical solution.
For companies aiming for complete biodegradability, PLA or PHA materials are the optimal choice, though they require new processing equipment and higher investment.
Both pathways represent the future of sustainable PET packaging — balancing performance, cost, and environmental responsibility.
