why does plastic take so long to decompose
Most plastic is manufactured from petroleum the end product of of once-living organisms. Petroleum's main components come from lipids that were first assembled long ago in those organisms' cells. So the question is, if petroleum-derived plastic comes from biomaterial, why doesn't it biodegrade? A crucial manufacturing step turns petroleum into a material unrecognized by the organisms that normally break organic matter down. Most plastics are derived from propylene, a simple chemical component of petroleum. When heated up in the presence of a catalyst, individual chemical units monomers of propylene link together by forming extremely strong carbon-carbon bonds with each other. This results in polymers long chains of monomers called polypropylene. "Nature doesn't make things like that," said Kenneth Peters, an organic geochemist at Stanford University, "so organisms have never seen that before. "
The organisms that decompose organic matter the ones that start turning your apple brown the instant you cut it open "have evolved over billions of years to attack certain types of bonds that are common in nature," Peters told Life's Little Mysteries. "For example, they can polysaccharides to get sugar. They can chew up wood. But they see a polypropylene with all its carbon-carbon bonds, and they don't normally break something like that down so there aren't metabolic pathways to do it," he said. But if all you have to do to make propylene subunits turn into polypropylene is heat them up, why doesn't nature ever build polypropylene molecules? According to Peters, it's because the carbon-carbon bonds in polypropylene require too much energy to make, so nature chooses other alternatives for holding together large molecules. "It's easier for organisms to synthesize peptide bonds than carbon-carbon bonds," he said.
Which means, according to, plastic does not decompose, biodegrade or compost, rather it just breaks down into smaller and smaller plastic pieces. "Plastics don't biodegrade like organic matter, which means they can't be converted by living organisms into useful compounds for life. Instead, they photodegrade, a process by which photons from the sun's rays pulverize the plastic polymers until they are broken into individual molecules. " (, clogging our landfills and even leaching toxins into our water table. Great, so microbes canБt eat plastic, therefore plastic is bad, right? Ish. б Ish you say? б WhatБs this ishБ please explain. б Well, you see, plasticБs inability to biodegrade is definitely problematic, but just refers to everything from the steering wheel of your car to the grocery bag you used to drag home those delicious organic berries (and that 10 pound sack of cheesies). In fact, some would argue that the plastic used in car manufacturing actually provides a net benefit to the environment because it is lighter than steel and makes cars more fuel efficient and therefore burns less fossil fuels. Grocery bags, plastic wrap, sandwich bags, ziplock bags and produce bags are more troubling because they are typically used once - maybe twice - and then discarded, where - as previously established - they will wind up in a landfill or somewhere out in the wilderness where they will never biodegrade. б And this begs the question that we - the consumers - must face. б Is the ease of use of plastics like grocery bags, styrofoam containers or disposable forks really worth the cost? б Now you know that those single use plastics cannot decompose, what are you going to do about it?
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