Current Status
PHA (polyhydroxyalkanoates) is a fully biodegradable polyester family with good biocompatibility, oxygen barrier properties, and food contact safety. These characteristics make it suitable for food packaging, including yogurt cups. In refrigerated storage (0°C to 10°C), PHA performs comparably to conventional materials in terms of mechanical strength, transparency, and heat-sealing.
The PHA grades we currently supply, primarily PHB-based, meet requirements for standard refrigerated conditions above 0°C. However, commercial yogurt cups are often exposed to lower temperatures (−10°C to −18°C) during frozen product storage or cold-chain transport. Pure PHB has a glass transition temperature (Tg) around 0–5°C, below which it becomes brittle and impact resistance drops significantly.
Market Context
At present, yogurt cups on the market are predominantly made from PP or PLA. PHA-based cups remain in pilot or small-scale use, mainly in Europe, with full commercial adoption still limited.
Challenges: Cold Chain & Cost
Temperature Sensitivity
The main limitation of our standard PHA grades for yogurt cups is low-temperature performance. When temperatures fall below 0°C, particularly to −10°C or lower, the material enters a glassy state, leading to reduced toughness. This can result in cracking during transport, dropping, or frozen storage, which may affect production yield and product reliability in full cold-chain scenarios.
Cost & Processing
Cost is a practical consideration: unmodified PHA remains more expensive than PP. Additionally, processing requires careful temperature control to prevent thermal degradation.
Technical Solutions
Several established modification approaches can extend PHA performance to sub-zero temperatures while preserving high biodegradability:
PHBV Copolymers
Increasing the hydroxyvalerate (HV) content to 10–30% lowers Tg to −10°C or below, significantly improving low-temperature toughness. PHBV maintains food contact compliance (e.g., EU 10/2011, FDA) and industrial compostability.
Plasticizer Addition
Incorporating bio-based plasticizers (such as citrate esters or lactic acid oligomers) at 5–15% reduces brittleness at −20°C without substantially affecting degradation rates.
Blending (PBAT/PBSA)
Combining PHA with PBAT or PBSA (30–50% blend ratio) achieves excellent impact resistance down to −30°C. Blends with PLA can further enhance strength and heat resistance. Most such blends retain >90% biodegradability under industrial composting conditions.
Multi-layer Structures
Using PHA as the food-contact inner layer and pairing it with tougher biodegradable outer layers provides both safety and robust low-temperature performance.
These modifications are compatible with standard thermoforming equipment, though minor process adjustments may be needed.
Implementation Recommendations
Standard Refrigeration (> 0°C)
Our current PHA grades can be used directly.
Sub-zero Performance
We recommend initial lab-scale or small-batch trials with modified grades or blends to verify mechanical properties.
How We Support You
- Material selection assistance
- Reference formulations
- Connection with compounding partners
