PHB Processability and Property Improvement with Linear-Chain Polyester Oligomers Used as Plasticizers

Area of Science:

• Materials Science
• Polymer Science
• Bioplastics

Background:

• Global petroleum-based plastic production exceeds 400 million metric tons annually, posing environmental concerns.
• Polyhydroxybutyrate (PHB) is a biodegradable, non-toxic alternative but suffers from poor processability and low deformation capacity.
• Improving PHB's processability is crucial for its wider adoption as a sustainable plastic.

Purpose of the Study:

• To enhance the processability and mechanical properties of polyhydroxybutyrate (PHB) using linear-chain polyester oligomers as plasticizers.
• To investigate the effects of different plasticizer concentrations on PHB's thermal and mechanical behavior.
• To identify the most effective plasticizer and optimal concentration for improving PHB's performance.

Main Methods:

• Two linear-chain polyester oligomers were synthesized and incorporated into PHB as plasticizers.
• Thermal analyses (including T_g and T_m determination) were conducted.
• X-ray diffraction (XRD) and polarized optical microscopy were used to analyze structural changes.
• Mechanical testing evaluated the impact on elastic modulus and maximum elongation.

Main Results:

• Both oligomers effectively plasticized PHB, reducing glass transition temperature (T_g) and melting temperature (T_m) with increasing concentration.
• Plasticizer 2 demonstrated superior performance, particularly at a 20% concentration.
• At 20% concentration, Plasticizer 2 decreased the elastic modulus by up to 72% and increased maximum elongation by 467%.

Conclusions:

• Linear-chain polyester oligomers can significantly improve PHB's processability and mechanical properties, addressing key limitations.
• Plasticizer 2 is a highly promising additive for enhancing PHB's flexibility and processability.
• Optimized use of plasticizers can facilitate the thermal processing of PHB and reduce degradation, paving the way for broader bioplastic applications.