Hi Chemical Engineers, what do you say about the following topic? 1

[saplanti]

It is about the plastics, and the author says the plastics are greener than other materials;
I guess you know about the chemistry of plastics better than me as a mechanical engineer. Please respond either here or on his post. Please notice his background and the companies that he had/has served.

https://www.eng-tips.com/viewthread.cfm?qid=484163

 

[SuperSalad]

I appreciate the sentiment because plastics are getting a very unfair shake from society in these times.

Some of the assertions appear a bit silly. I especially would argue the point of:

Plastics degrade into carbon dioxide and water just like other organic matter like leaves, sticks, food and so. They degrade at about the same rate as those materials too.

The part about the degradation rate is unarguably false. Like outstandingly so. I don't know how anyone could even say that with a straight face.

Some biodegradable plastics do pretty well on that front, but even those specialized plastics require an industrial digester to come even remotely close to the decomposition rates of leaves, sticks, and food.

Andrew H.

http://www.MotoTribology.com

 

[Compositepro]

Most plastics do degrade fairly quickly and require the addition of antioxidants and other stabilizers to have useful lives. Once the additives get consumed in their normal course of action plastics degrade at the normal rate. Microbes do not eat most plastics but ultraviolet light from the sun degrades all organic materials to, yes eventually, CO2 and water. With some plastics the intermediate degradation products may not be good for you but the concentrations are very tiny because degradation and dilution occur simultaneously.

To the vast majority of the population the word 'chemical' has evil connotations, although every substance in the universe is a chemical.

 

[horacio Torres]

Plastics degrade into carbon dioxide and water just like other organic matter like leaves, sticks, food and so. They degrade at about the same rate as those materials too.


Like Supersalad say, this statement is false  at least is a false true.
Leaves, MO , tree and stick will degraded to co2 and water in 2 months
PP PE Pu becomes degraded 500 years, creating a nanoplastic layer at first. later bacterias become to degradeted
Of course in 500 years they will become co2, but it is a false statement..

Horacio

 

[saplanti]

I do not deny that usage of some plastics reduces the pain of mechanical engineers a lot. However I am convinced that the plastics are the pollutants after reading too many articles about. I attached some of them to the original post. These articles are mainly UN backed articles and there are many supporting evidence and papers behind them.

For me, at least the images taken from the oceans, from the poor countries are sufficient to claim it. If you look at the wikipedia article you will not see any plastic manufacturer and developed country in the list of plastic polluters in 2010. Because they do send their polluters to the listed countries to recycle by hand, than burn some of them, and bury the leftover in the soil. As expected they cannot manage all these and most of the plastics mix with ocean water and float. Fourth article explains that burning cause toxic gases and causes problems in human health.

So the main producers of the plastics do not manage the process to recycle the plastics, therefore the plastics become pollutant in our life cycle. This is called consumerism, and freedom of the polluter societies. Same thing happens with almost everything that we use such as hand held telephones, electronics, kitchen gadgets whatever we can think of. We used to get things repaired and use again and again. Now, we throw everything since the new is cheaper, the new model is better. Let us not forget that this also cause unemployment, lose of mastering in a job in the society since the we can find fabricated things cheaper. There used to be a corner shop to shop the needs, not anymore, we have shopping centres that you can find almost anything. Some can say that nothing wrong with it. True in very short term, but not in a long term (plastic pollution is one of them, you probably are aware of the CFC that we removed from our life last 10 years and replaced all the fridges and air conditioning units).

I hope the new generations can live in a better society, free of pollutants, and with clean air.

 

[Demon3]

Hello horacio Torres,

Your statement is incorrect. See the scientific proof here if you're interested to learn

https://plasticsparadox.com/do-plastics-last-forever/

All the best,

Chris

Chris DeArmitt PhD FRSC
President

Plastic materials consultant to the Fortune 100 - As seen on CBS 60 Minutes, BBC & Sky News
Creating New Materials - Problem Solving - Innovation Keynotes - Expert Witness

http://www.phantomplastics.com

 

[3DDave]

It's true. Plastics won't last forever. When the Sun reaches the Red Giant phase no plastics will remain.

No argument from me on that evidence. Same reason I don't argue with flat-earthers or anti-vaxxers.

Especially the case when I can go out to my 40 year old plastic trash cans and see no evidence of rot or biological decomposition and only slight surface damage from UV exposure from those 40 years under the open sky. Were it not for squirrels they would be like new. OTOH my leaf pile would be 70 feet tall were those not to decompose, so any claims about the relative rate being less than 100:1 are literally garbage.

 

[IRstuff]

While Kynar isn't a conventional "plastic," after 20+ yrs in the sun on my roof, there's only marginal deterioration.

OTOH, plastic grocery bags deteriorate into smaller pieces that do get into everywhere.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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[horacio Torres]

Hello Demon3

I am not an ambientalist, i must said.. but I worked in the main plastic producer in Vzla for 20 years as a plant manager, Later as consulting Engineer a company ask me to recovery and dispose 30 TM of PU,PVC,PP,PE located into a warehouse for more that 20 years, nothing were degraded, only broken by mechanical reasons. No bio attack, sunlight effects on others..It for me, was a surprise.

I will let a paper about plastic degradation in the forest and sea, as good researchers need more investigation, they could not establish any proof of degradation.

https://www.researchgate.net/public...dation_of_Various_Plastics_in_the_Environment

Best regards

Horacio

 

[IRstuff]

Certainly, there used to be a time when plastics in sunlight would deteriorate relatively quickly, but the past 3 decades or so have brought forth UV stabilizers that have allowed for the production of engineered plastics specifically for outdoor and direct sunlight use, such as fencing, siding, roofing, and decking, etc. So, below is the claim of "last a lifetime;" even assuming they really mean 20-30 years, the mean time to complete disintegration would be more than a century.

Why Use Lifetime Vinyl Fence?
Lifetime Vinyl Fence is a company which was founded in 1999. We have highly qualified and professional staff and over 15 years of experience in installation of Vinyl Fences. We carry over 30 different styles and variety of vinyl. Vinyl Fence has become very popular over the years. Vinyl lasts much longer than wooden fence and is stronger and more durable than wood. It does not decompose, it is rust free, and prevents dealing with termite issues. Vinyl maintains its original look and does not require painting. It can last a lifetime and requires low maintenance.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[Compositepro]

Those of you who are are arguing that plastic do not degrade are defeating your own arguments about plastics being harmful. If they don't degrade they are inert and therefore cannot harm the environment any more than sand and dirt. I would like to see a 40 year old plastic trash can.It would be worth a lot to the manufacturer for marketing purposes. My experience is quite the opposite, in that they rarely last more than a couple years.

 

[IRstuff]

If they don't degrade they are inert and therefore cannot harm the environment any more than sand and dirt.

So, there are animals trapped by those plastic 6-pack rings, etc.

I've been using the same garbage bins for 12 years, and the only damage is from bent METAL axle. The bin itself is just fine and dandy, although the print and labels have disintegrated. Likewise, 20 years on the Kynar coatings on the roof; my neighbor's still looks the same as the day he installed his roof. Mine got beat up because I went cheap and didn't install the stryofoam underlayer that would have kept contractors' shoes from tweaking the metal.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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