Process for the synthesis of PHB bioplastics

PHB (polyhydroxybutyrate) is a biocompatible thermoplastic polyester that can be produced from renewable starting materials. However, pure isotactic PHB produced by conventional fermentation processes has limited application potential since it is very brittle and its melting point (which must be reached for hot molding) is very close to its decomposition temperature. Improved material characteristics more similar to those of well-established petrochemical plastics such as polypropylene are essential for competitiveness of PHB bioplastics.

The innovation includes new chemical processes for the synthesis of PHB from ­regenerative carbon sources, using a highly effective catalyst system and racemic β-butyrolactone as a ­starting material. During the process, conditions can be tuned to obtain different (R)/(S) ratios. The resulting PHB shows improved material properties, especially higher tensile ­elongation (plasticity and elasticity) and a lowered melting point for simpler processing. Variation of synthesis conditions allows the specific formation of a variety of PHB microstructures with ­different material properties.

Characteristics of the resulting innovative bio-plastics:

• biocompatible, biodegradable and water proof
• thermoplastic properties are comparable with petrochemical plastics
• suitable for injection molding
• can be stained, printed and laminated

PHB is used in many commercial sectors:­

• Packaging (e.g. food & pharmaceutical industries)
• Consumables
• Textiles
• Electronics
• Automotive & Transport
• Construction

Established method on a laboratory scale.