Polyhydroxybutyrate (PHB) modified with clay nanoparticles could be the next wave in the biodegradable plastics market. PHB, produced by bacterial action, is a rare example of hydrophobic polymer that is truly biocompatible and biodegradable with high melting temperature and crystallinity.

In a study scientists in New York report they have developed a new biodegradable “nanohybrid” plastic that can be engineered to decompose faster than the existing plastics used in everything from soft drink bottles to medical implants.

The new nano-engineered plastic might provide additional competition in a market that is ramping up to meet the demands posed by environmentally conscious consumers and EU waste regulations.

PHB has been widely hailed as a green alternative to petroleum-based plastic for use in packaging, agricultural and biomedical applications, state Emmanuel Giannelis and his two colleagues, who are engineering and food scientists at Cornell University.
However although PHB has been commercially available since the 1980s, the plastic has had limited use because of its brittleness and unpredictable biodegradation rates.

PHB, produced by bacterial action, is a rare example of hydrophobic polymer that is truly biocompatible and biodegradable with high melting temperature and crystallinity, they stated. “However, its strength and some other properties such as thermal stability, gas permeability, solvent resistance, and flame retardance are sometimes not enough for end use,” they added.

In the study, the scientists compared the strength and biodegradation rates of raw PHB to a modified form of PHB that contains nanoparticles of clay or ‘nanoclays’.

The scientists found that the modified PHB was stronger and decomposed faster than regular PHB. The nanohybrid PHB decomposed almost completely after seven weeks, while regular PHB exhibited almost no decomposition, they stated in a paper.

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