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Author: Subject: Demonstrations about the science of plastics
EliasExperiments
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[*] posted on 22-3-2021 at 09:54
Demonstrations about the science of plastics


Right here you can find a video series I started about the science of plastics:

https://youtu.be/AXz4TQO3-D8

Are there any demonstrations you guys know about plastics that I definetly should not forget?
The next video will be about the history of plastics, then there will be a video about plastics and fire, about the synthesis of polymers, about functional polymers and about recycling.
If anyone has any ideas for each of these categories that would be great.
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Maurice-VD-3
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[*] posted on 28-3-2021 at 11:50


Try to cut a rectangular piece of polyethylene (or polythene) about 2 to 5 cm broad and 20 - 30 cm long. Hold it between your hands and draw smoothly in order to extend it a bit. The band will extend a bit. Don't draw too strongly, in order to avoid a break. When you have extended it so that the length is about the double of the original length, have a look over its appearance. You should see that in the middle of the band, there is a rectangular zone where the band is rather narrow. If you continue drawing for extend it, this narrow zone will increase and occupy all the plastic ribbon which its nowhere the one meter long. But, when this is done, you cannot extend it any more. You may try it to draw it more. This shows that now all molecules of the polymer are then alined along the ribbon. You may have the audience repeat this same experience. with a new rectangle.
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mayko
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[*] posted on 28-3-2021 at 12:05


A classic demo is to pour some adipic acid chloride into a beaker and layer on top of it hexamethylenediamine... at the interface of the two liquids, Nylon-6,6 forms, and if you get ahold of it, you can draw up a thick thread of nylon.

Other diacid dichlorides (eg, Sebacoyl) are sometimes used for other Nylons:
https://www.sciencelabsupplies.com/Nylon_6-10_Rope_Trick.htm...

I've always been curious about what would happen if aerosols of the two mixed. Maybe that could be your novel angle?




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Fulmen
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[*] posted on 28-3-2021 at 12:52


Don't forget the first polymer: Cellulose. Making Rayon isn't too hard to pull off...



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EliasExperiments
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[*] posted on 30-3-2021 at 08:36


@Maurice-VD-3 Wow this sound really interesting. I'll see if I can get it to work.

@mayko Yes that will definetly be included. Using an aerosol sounds interesting. But how would I best go about creating that?

@Fulmen Yes cellulose and cellulose nitrate will certainly be included. Rayon also sounds like a great idea. I guess I will put that in my video about recycling of polymers.

Thank you all for the suggestions!
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Bedlasky
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[*] posted on 30-3-2021 at 09:14


Here you can find some tests for cellulose derivatives and polyvinylacetate.

I like this test:

General Test with Benzene

Reagent

Solution 1: benzene (caution: known carcinogen)
Solution 2: 93% sulfuric acid
Solution 3: alcohol

Availability: Self-prepared.

Procedure: Place solid sample in test tube with 0.5 ml
benzene (caution: known carcinogen) and 1 nil sulfuric
acid. Carefully warm test tube in water bath (caution:
use fumehood and point test tube opening away) until
yellow color develops and rapidly turns red. Allow to
cool and add a layer (0.5 ml) of alcohol without stirring
(Browning 1977, 273).

Sensitivity:

Results: All cellulosics show a blue or green ring
between the two liquid phases except for ethylcellulose,
which shows a violet ring (Browning 1977, 242).

Caution/Interference: This test works for water-soluble
ethers. Take extreme care in handling benzene.




If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

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yobbo II
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[*] posted on 2-4-2021 at 16:04



A test done years ago for the hardness of certain plastics using pensils I can remember.

A set of pensils of graded hardness. Some do not scrape some plastics some do. You can ascertain the relative hardness.

Pencils are graded in 9 number and 3 letters.

The range goes from 9H (hardest), 8H 7H, 6H, 5H, 5H, 3H, 2H, H, F, HB, B, 2B, 3B, 4B, 5B, 5B, 6B, 7B, 8B and 9B

Yob
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[*] posted on 20-4-2021 at 05:46


https://www.youtube.com/results?search_query=japanese+guy+re...
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Praxichys
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[*] posted on 20-4-2021 at 06:42


Here are a few ideas:

- Urethanes and their properties, urethane expanding foam
- Plastic foams and their uses - styrofoam, foam rubber, open/closed cell - sponge, air filter, seat cushion, plant support material
- Silicones, their structures, uses, and forms - RTV silicone caulk and curing through hydrolysis of acetyls
- Natural rubber vs synthetic rubber; "vulcanization" and what is happening - vulcanize some natural latex
- Butyl and nitrile rubbers, properties, applications
- Polyesters and their chemical structures and uses - PET bottles and clothing, vacuum forming and blow molding, using an iron to thermoform polyester clothing
- PVC and CPVC manufacture and its high wt% chlorine
- Acetals like POM (Delrin), "engineering plastic" machinability and low friction properties
- Acrylics, PMMA, and polycarbonates; lexan, plexiglas, acrylate super glue
- PTFE and its discovery, uses, and why perfluorinated polymers are so chemically inert
- Polyaramids and UHMWPE as ultra-strength materials, use in soft armor, sailcloth, ropes
- Recycling groups and why they are important
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njl
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[*] posted on 20-4-2021 at 07:55


If it counts, one of the first experiments I ever tried was testing the yield of solid from milk when mixed with different acids. The solid is allegedly casein, which dries to form a hard plastic-like material. At the time all I knew was that I had vinegar and hydrochloric acid, and that vinegar is a weaker acid than HCl. Looking back I was probably using 5 percent vinegar from a gallon bottle I bought at a local hardware store. At the same store I bought the concentrated HCl. So, some arbitrary but consistent amount of whole milk is added to an equal volume of acid in a beaker (or more likely a jar at the time) and microwaved for a few minutes. The solution was removed and allowed to cool, the solids then congealed and were filtered out. The solids were dried with paper towels and left to harden overnight. If I recall correctly HCl yielded more solids. Queue tri-fold board and glue sticks, et viola: third grade science project.



Reflux condenser?? I barely know her!
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EliasExperiments
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[*] posted on 20-4-2021 at 09:11


@pneumatican that is actually a great idea, but that might be really complicated. There is actually a good place for this experiments in this series. You will get credited of course

@Praxichys Funny enough I just filmed the first experiment on that list today. Silicone was already feature in my most recent video:
https://youtu.be/MSraRbRFmPY
But yes they deservere there entire own video, or probably even series.
I have also already filmed some rubber for my video on history and did some experiments for vulcanized vs raw rubber but that also would deserve it's own video.
Acrylics will be mentioned for how good they are to be recycled.
PTFE is a little too dangerous for me to do experiments with, but that would also deserve an entire own video.
Kevlar is certainly intersting, but for this series regular nylon will have to do. :D
Recycling will get it's own video, but I won't make it too technical.
Those are all great ideas, that certainly will be featured in part in the series so thank you so much for all the input!

@njl That is plastic in theorie, but not of much practical use today as far as I am aware. Sure it is a great experiment for beginners, and I might find a place for it. So thanks a lot for the suggestion!
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