Hi, this is Emily from MinuteEarth.
Plastic is incredibly strong,
and can be molded into a mind-boggling array of stuff.
But that strength also makes plastic stick around long
after we actually need it,
because unlike most materials,
it simply doesn’t ever fully break down.
Each type of plastic is made of one chemical unit,
such as ethylene,
repeated thousands of times over in long, noodle-like strands,
which is why plastics’ names all start with “poly,”
the Greek word for “many.”
Quadrillions of those strands get tangled together
like cooked pasta to form everything
from saran wrap to space shuttle sheathing.
forces like heat and tension
can separate the tangled strands of plastic from each other,
causing big pieces of plastic to break into smaller ones.
But the individual strands themselves are glued together
by thousands of carbon-carbon bonds,
which are among the strongest types of chemical linkages:
neither normal amounts of heat and pressure,
nor the other usual destructive forces,
can break them.
So while large bits of plastic break apart into small bits,
those small bits never really disappear.
So scientists are noodling around
for a way to create less permanent plastics.
New versions, such as polylactide,
are still made up of repeating chemical units,
but instead of those everlasting carbon-carbon bonds,
the chains are held together by different types of links,
like carbon-oxygen bonds,
which can be easily cut – even by water –
and the resulting bits can ultimately be digestedby bacteria.
So after a few dozen years out in the world –
or just a few months in the right processing facility
– these new plastics can degrade completely into just carbon dioxide and water.
But so far, there are some drawbacks:
polylactide, for example,
is more expensive than traditional plastics,
and the carbon-oxygen bonds that make it degradable
also give it a fairly low softening point,
making it not so practical for some uses.
So, we still haven’t cooked up the perfect plastic yet,
but scientists are excited about the pasta-bilities.
This video was sponsored by the University of Minnesota,
该大学所有学科领域的学生 教员 职工
where students, faculty and staff across all fields of study
are working to solve the grand challenges facing society.
One of those challenges is to ensure
that we have clean water and sustainable ecosystems,
and part of the solution is to develop technologies that are better for the planet.
In the Department of Chemistry,
Professor Marc Hillmyer and the researchers in his group
如研究生Guilhem De Hoe
– like graduate student Guilhem De Hoe –
are creating biodegradable plastics made from renewable resources,
and they are working with the University ’ s Center for Sustainable Polymers
发展新型的 有前景的 可商业化的塑料
to advance promising new plasticcandidates towards commercialization.
Thanks, University of Minnesota!