'Green' plastic from shrimp shells to stop pollution

Harvard scientists have developed an environmentally safe alternative to plastic isolated from shrimp shells.
Researchers at Harvard University's Wyss Institute for Biologically Inspired Engineering have introduced the new bioplastic made from chitosan, a form of chitin - the second-most abundant organic material on Earth.
Chitin, a tough polysaccharide, is the main ingredient in the hardy shells of crustaceans, the armour-like cuticles of insects, and even the flexible wings of butterflies.
The institute makes its shrilk from chitin from shrimp shells, most which would otherwise be discarded or used in fertiliser or makeup, and a fibroin protein from silk.
Shrilk is cheaply and easily fabricated by a novel method that preserves chitosan's strong mechanical properties.

The researchers said that for the first time, this tough, transparent, and renewable material can be used to make large, 3-D objects with complex shapes using traditional casting or injection-molding techniques.

That means objects made from shrilk can be mass-manufactured and will be as robust as items made with the everyday plastics used in toys and cell phones.
"There is an urgent need in many industries for sustainable materials that can be mass produced," Wyss Director Donald E Ingber said.
"Our scalable manufacturing method shows that chitosan, which is readily available and inexpensive, can serve as a viable bioplastic that could potentially be used instead of conventional plastics for numerous industrial applications," said Ingber.

This environmentally safe alternative to plastic could also be used to make trash bags, packaging, and diapers.
Once discarded, shrilk breaks down in just a few weeks - and even releases rich nutrients that support plant growth.
In one experiment, researchers grew a California black-eyed pea plant in soil enriched with its chitosan bioplastic.
Within three weeks, the material encouraged plant growth.
In environmental terms, finding viable alternatives for conventional plastics - prized for their lightness, durability, and low price - is an urgent matter.
According to researchers, plastics buried in landfills will take 1,000 years to degrade.
Plastics discarded into the world's seas - an estimated 100 million tonnes so far, circulating in vast oceanic gyres - are a threat to marine life, researchers said.

The study was published in the journal Macromolecular Materials & Engineering.