Why can't they make biodegradable plastic?

johnflesh

Former Staff
Feb 2007
28,597
21,552
Weirdo
So that it will self-degrade/disappear after "X" number of years.
Thoughts?
They already do, sort of.

The idea behind making say, a traditional biodegradable plastic bag breaking down over x amount of years is untenable as plastics are made to be very durable. Also the breakdown process often involves direct sunlight or industrial composting which doesn't do much for those bags below the surface in a landfill.

However there are things like bioplastics which are made from natural ingredients like corn starch. On the flipside, when they degrade they release methane gas.
They also need direct sunlight to break down and can still leave behind toxic residues and fragments.

Fun fact. Plastic grocery bags are designed to last 500 years but are on average only used for no longer than 12 minutes.
 

Devil505

Former Staff
Jan 2008
74,295
32,597
Florida
They already do, sort of.

The idea behind making say, a traditional biodegradable plastic bag breaking down over x amount of years is untenable as plastics are made to be very durable. Also the breakdown process often involves direct sunlight or industrial composting which doesn't do much for those bags below the surface in a landfill.

However there are things like bioplastics which are made from natural ingredients like corn starch. On the flipside, when they degrade they release methane gas.
They also need direct sunlight to break down and can still leave behind toxic residues and fragments.

Fun fact. Plastic grocery bags are designed to last 500 years but are on average only used for no longer than 12 minutes.
So "The Graduate" was onto something!!!!
 
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Libertine

Moderator
Apr 2015
16,947
3,446
Katmandu
They already do, sort of.

The idea behind making say, a traditional biodegradable plastic bag breaking down over x amount of years is untenable as plastics are made to be very durable. Also the breakdown process often involves direct sunlight or industrial composting which doesn't do much for those bags below the surface in a landfill.

However there are things like bioplastics which are made from natural ingredients like corn starch. On the flipside, when they degrade they release methane gas.
They also need direct sunlight to break down and can still leave behind toxic residues and fragments.

Fun fact. Plastic grocery bags are designed to last 500 years but are on average only used for no longer than 12 minutes.
Exactly, polymers are biodegradable, but since they are designed to replace metal and wood parts, they contain additives to extend life. A polymer without anti-oxidants would fall apart in a few years, which is very undesirable in your automobile or appliances.

The insulation on the wiring harness of my car is made from a soybean based polymer and mice find it delicious, already had one expensive repair and I was lucky it didn't get the main trunk.

After a couple of years I find plastic grocery bags to be useless.
 
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Ian Jeffrey

Council Hall
Mar 2013
79,922
50,439
Vulcan, down the street from Darth Vader
After a couple of years I find plastic grocery bags to be useless.
Even paper bags with handles tear too easily (my city outlawed the plastic bags). Reusable bags are much better ... I somehow came into possession of a couple and use them for most grocery shopping. Once in a while I'll get bags because I use them to collect my recycling. If I need paper bags badly enough, I can go to the next town over (just a few minutes' drive for me) and buy some groceries there.
 
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Devil505

Former Staff
Jan 2008
74,295
32,597
Florida
Even paper bags with handles tear too easily (my city outlawed the plastic bags). Reusable bags are much better ... I somehow came into possession of a couple and use them for most grocery shopping. Once in a while I'll get bags because I use them to collect my recycling. If I need paper bags badly enough, I can go to the next town over (just a few minutes' drive for me) and buy some groceries there.
My wife uses the cloth bags too.
Much stronger