If the over-reliance on petroleum for plastics production is not already a problem, the plastics pollution crisis is and will remain the most concerning environmental issue for citizens across the globe for many years to come.
To address both issues, researchers are working against the clock to come up with alternatives that is neither fossil fuel-based nor harmful to the environment. A recently published study reported a new alternative to plastics which combines the sturdiness of natural rubber and the eco-friendliness of a bioplastic known as PHBV, according to the authors from the Ohio State University.
Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) or PHBV, the copolymer of two short-chain organic acids, is a bioproduct generated by genetically engineered E. Coli. Considered as a promising alternative to conventional plastics, it is both biocompatible and biodegradable.
PHBV has been made in medical implants and release-controlled capsules because it is not toxic and undergoes slow degradation in aqueous environments. Once disposed of in the landfills or even natural environments, PHBV gets chewed by microbes and turned into carbon dioxide and water as quickly as 6 weeks. But one of its main drawbacks is that it is easy to break and cannot stand strong physical impact, which limits its wide industrial applications.
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Natural rubber (NR), polymers of isoprene, is harvested in the form of latex from rubber trees. It is stretchable and highly resilient to physical stress, and yet susceptible to bacterial degradation. NR is commonly added during the productions of many polymer-based products, as a toughening agent. But the Ohio State team went to a couple of steps further.
The team of material chemists added an acrylic coagent (to perform cross-linking between PHBV and NR) and an organic peroxide (to catalyze the polymerization) in their process, which allow PHBV to be firmly grafted onto the rubber backbones. The two additives also decreased PHBV crystallinity and crystal size, making the final PHBV-NR blend much less brittle.
With 75% tougher and 100% more flexible than PHBV alone, the bioplastic and natural rubber mix holds great promise to replace the current food packaging material, which constitutes the largest source of single-use plastics at the moment.
“Previous attempts at this combination were unsuccessful because the softness of the rubber meant the product lost a lot of strength in the process,” commented Xiaoying Zhao, the lead author and a postdoctoral researcher on Food Science and Technology, in a press release. Their newest introduction, however, would make a difference.
Besides food packaging-related applications, the team hopes that the PHBV-NR can also find its way to many other areas such as cutleries and kitchenware, medical implants, construction material, as well as automobile and aeronautics manufacturing.
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Source: ZME Science