Starch-based Bioplastic

Quick Overview

Starch-based bioplastics are created from renewable starch sources like corn, potato, or cassava. The most cost-effective bioplastic option, they're fully biodegradable and widely used in packaging and agricultural applications.

What Are Starch-based Bioplastics?

Starch-based bioplastics are produced from starch sourced from crops such as corn, potato, cassava, wheat, or rice. They represent the most cost-effective bioplastic option and are fully biodegradable in industrial composting, soil, and — for some grades — marine environments.

Pure starch alone cannot be processed like conventional plastic. It must be converted into thermoplastic starch (TPS) by adding plasticisers (glycerol, sorbitol) and blending with biodegradable polymers like PBAT or PLA.

Production Process

1. Starch extraction: Crops are processed to isolate starch granules
2. Gelatinisation: Starch is heated with water and plasticisers to break granular structure
3. Blending: TPS is blended with PBAT, PLA, or other biodegradable polymers
4. Compounding: Melt-blended in twin-screw extruder to form pellets
5. Processing: Pellets processed on standard equipment (film blowing, injection moulding)

Starch/PBAT vs. PLA/PBAT

Key Applications

Compostable Bags (Largest Market)

• Shopping bags, produce bags, organic waste bin liners
• Low cost makes starch/PBAT the preferred material

Agricultural Mulch Films

• Laid on soil surface, biodegrade after harvest
• Eliminates removal and disposal costs
• Certifications: EN 17033 for biodegradable mulch films

Loose-fill Packaging

• Biodegradable “peanuts” replacing expanded polystyrene
• Compostable after use

Food Service

• Cutlery, plates, cups, containers
• Fully compostable with food waste

Environmental Benefits

• Lowest cost among bioplastics — closest to fossil plastic pricing on a per-kg basis (carbon footprint included)
• Bio-based from abundant, renewable feedstocks
• Food-safe for food-contact applications
• Compostable — returns nutrients to soil

Limitations

• Moisture sensitivity: Starch-based materials absorb water, losing mechanical properties in humid conditions
• Limited thermal stability: Cannot withstand high processing or use temperatures
• Variable properties: Performance varies with starch source, plasticiser content, and blending partner
• Not suitable for wet or humid environments without protective coatings

Frequently Asked Questions

What crops are used for starch-based bioplastics? Corn (most common in the US), potato (Europe), cassava (Asia, Latin America), wheat, and rice. The starch source does not significantly affect material properties.

Are starch-based bioplastics edible? While starch itself is food-safe, starch-based bioplastics contain plasticisers and blending polymers that are not intended for consumption.

Do starch-based plastics contaminate recycling? Yes. They should not enter conventional plastic recycling. They belong in composting (organic waste) streams.

Can starch-based bioplastics degrade in home compost? Many starch/PBAT grades degrade in home compost over 6–12 months, but degradation is slower and less reliable than in industrial composting.

Related Terms

• PBAT — The polymer most commonly blended with starch
• Bioplastic Blends — Starch/PBAT as a key blend system
• Compostable — Starch-based blends meet EN 13432 standards
• EN 13432 — The relevant compostability standard
• Feedstock — Starch bioplastics use 1G and 2G feedstocks
• Biodegradable — The fundamental end-of-life property