Biomaterials

Scientists make biodegradable plastic from cactus juice

Friday, June 14, 2019

Engineers figured out a way to cut down on the amount of single-use plastics clogging our landfills and polluting the oceans — replacing them with a material made from prickly pear cactus.

The new plastic alternative, mostly comprised of juiced cactus leaves, rapidly biodegrades and doesn’t require crude oil like traditional plastics do, according to BBC News — a potentially less harmful way to package food and other goods.

The new alternative plastics start to break down after sitting in the soil for a month. In water, they break down in a matter of days, the BBC reports.

“It’s a non-toxic product,” Sandra Pascoe Ortiz, the University of the Valley of Atemajac engineer who developed the material, told the BBC. “All the materials we use can be ingested both by humans or animals. And they wouldn’t cause any harm.”

That means even if the fake plastics make their way into the ocean, they’ll either feed the fishes or dissolve instead of hurting wildlife.

Right now, the manufacturing process is largely limited to Ortiz’s lab, where she spends ten days making a batch out of cactus juice and a blend of other renewable ingredients.

But Ortiz told the BBC she thinks the process could be sped up enough to compete with conventional plastic if her operation is scaled up and moved to an industrial facility.

Another plastic solution

As of 2015, Americans recycled less than 10 percent of the plastics they used, and not only because they’re lazy: Many plastics just aren’t conducive to recycling.

Now, scientists from Berkeley Lab say they’ve created a plastic that can be broken down and recycled indefinitely — and it could help the world address its ever-growing plastic pollution problem.
Tight Bond

All plastics comprise large molecules called polymers, which in turn comprise compounds called monomers.

Often, the chemicals added to plastics to give them desirable traits — rigidity or flexibility, for example — bind so tightly to these monomers that they stick around even after the plastic goes through the recycling process.

The problem is that when manufacturers use the recycled monomers to make new plastics, they can’t know for sure what properties the new plastic might inherit from the original.

Acid Test

But in a study recently published in the journal Nature Chemistry, the Berkeley team details its creation of a new kind of plastic called poly(diketoenamine), or PDK.

Instead of being permanent, the bonds between the chemical additives and monomers in PDK are reversible — they dissolve when the material is placed in a highly acidic solution, which allowed the researchers to use the reclaimed monomers to create a recycled plastic that didn’t exhibit the same properties as the recycled plastic.

“Most plastics were never made to be recycled,” researcher Peter Christensen said in a press release.”But we have discovered a new way to assemble plastics that takes recycling into consideration from a molecular perspective.”



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