US researchers develop NR-reinforced bioplastics

Researchers at the Ohio State University have combined natural rubber (NR) with bioplastics to develop a “tough and flexible” biodegradable material.
 
The biocompound is “a much stronger replacement for plastic,” said the university in a report published in the journal Polymer in March.
 
The study involved melting rubber into bio-based poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) along with an organic peroxide and trimethylolpropane triacrylate. 
 
Previous attempts at this combination failed because the softness of the rubber meant material strength fell by as much as 80%, said lead author Xiaoying Zhao. 
 
The new process reduces the strength of the PHBV thermoplastic by only 30%, said Zhao, a postdoctoral researcher in food science and technology.
 
Already “capturing the interest of companies”, the product is 75% tougher and 100% more flexible than PHBV, the university added.
 
According to Zhao, the material’s increased flexibility, without a significant loss of strength, is particularly helpful within the packaging industry, where plastic films are commonly used to package everything from fresh produce to frozen foods.
 
Also commenting on the study, co-author Katarina Cornish pointed out that toughness was different from strength.
 
“Imagine trying to pull a block of concrete apart with your hands. That’s testing its strength. But karate chopping it with your hand or foot is testing its toughness – how easily it breaks,” the natural rubber expert explained.
 
“You can never pull it apart, but if you’re strong enough you can break it,” she added.
 
The researchers are now working on the potential use of various biodegradable materials such as post-consumer coffee grounds, tomato skins and eggshells as filler materials to strengthen the mix.