The Polymer Explosion: Crash Course Engineering #20
ฝัง
- เผยแพร่เมื่อ 3 ต.ค. 2018
- We’re continuing our look at engineering materials with third main type of material that you’ll encounter as an engineer: polymers. They’re made of long, repeating chains of smaller molecules known as monomers and today we’ll explore their strange history of polymers and the things that contributed to how we use them today.
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RESOURCES:
www.slate.com/articles/news_an...
www.britannica.com/science/po...
www.pslc.ws/macrog/kidsmac/bas...
www.livescience.com/60682-pol...
www.britannica.com/science/co...
www.britannica.com/science/el...
www.cmu.edu/gelfand/education...
pslc.ws/macrog/kidsmac/xlink.htm
www.britannica.com/technology...
news.nationalgeographic.com/n...
www.britannica.com/science/po...
sciencebob.com/make-your-own-...
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www.britannica.com/biography/...
www.theatlantic.com/technolog...
www.britannica.com/science/po...
physics.aps.org/articles/v11/29
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To provide more learning, I can add a mini-crash course on some polymers and plastics info.
The big thing with plastics is that they are generally divided into 2 types: Thermoplastic and Thermoset. Thermoplastics can be melted and solidified over and over again, and do not have any cross linking, or bonding between the chains of polymers. Thermosets have lots of cross linking, and cannot be melted once solid. Thermoplastics are characterized by being melt-processable, meaning all manufacturing methods involve melting the plastic into a liquid, then forming it into the shape you want and cooling it there. Common methods of melt processing include injection molding, extrusion, and thermoforming. Thermosets, since they cannot be melted, have to be created on a chemical level in their final form. This means that you start with a liquid uncured polymer and an initiator (a chemical that causes the polymer to cure). You then mix the two parts and pour of flow the liquid mix into position, then let it cure and solidify in place. A store bought 2-part epoxy is an example of this. Carbon Fiber and glass fiber panels are examples of things made with thermosets, the fiber weave is encased in a cured thermoset.
The plastic property mentioned that might aid water flowing higher is a reference to the fact that thermoplastics, when loaded in shear like being forced through a pipe, will reduce in viscosity. Normal liquids increase viscosity and resist flow the more you push, but plastic will flow more. This is a result of the long polymer chains lining up in the direction of flow, but the alignment increases the more you push on them, resulting in lower viscosity the harder you push.
Another fun property of plastics is the glass transition. Most thermoplastics have 2 different phases of being solid. Below the glass transition temperature, they are stiff like glass, and will be brittle. Plastics like Polycarbonate, used for safety glasses and blast shields, is below its glass transition temperature at room temp. Plastics that are soft and can be belt and folded, like a ziplock bag, are above their glass transition temperature at room temp. When a plastic like polycarbonate is brought above its glass transition temperature, which is less than the melt temperature, it will become soft and wobbly.
Speaking of temperatures, thermoplastics do not have a definitive melt temperature. Metals have a temp that they always melt at, but plastics generally have a range, and some have no discernible transition from solid to liquid. Melt for a plastic is defined as the point at which there is enough heat energy for the long chains to slide past each other to allow for flow. This mainly takes the form of breaking crystalline regions of the plastic (polymers can be semi-crystalline on a microscopic scale, with small areas of crystal structures and small areas with no structure, called amorphous). The longer the chains are, the higher the melt temperature as its harder to get them to slide past. So 1 plastic can have a range of melt temps depending on the particular molecular weight, or average chain length, of that sample. Polymers that have no crystal regions are called "Amorphous", and they have no definitive temp at which they melt. From the glass transition temperature to the point where they start to degrade and burn, they just gradually lose viscosity and stiffness. There is no hard line that says "this plastic is now liquid". You can just turn the temp up or down a little, and it will just get a little less or more viscous.
Well there is a little deeper into the subject at a very, very brief overview with some fun info. Hopefully someone enjoys reading it!
-Source: Plastics and Composites Engineering student senior.
P.S. don't pronounce the "ph" in Terephthalate. Its to much of a mouthful so everyone in industry just skips those letters.
Fun fact: Nylon, Kevlar and Teflon were all created by the same company, DuPont. They also created Nomex (a fire-resistant fabric) and Spandex.
And they are all trade names
Shut up
legendary men... They even sponsored a legendary man.
Important piece of information about elastomers: they absolutely must be cross-linked to return to their original shape, otherwise they just deform permanently (which means they flow like a syrup, in this context)
The cross links don't necessarily need to be covalent bonds though. Also, cross-linked elastomers will deform permanently if you stretch them out for a long enough time, and they'll contract if you heat them while they're stretched. Polymers are weird as hell, basically & Silly Putty is magic.
Another fun bit of information: you totally can use polymers to build buildings, planes, boats and such, so long as you combine it with something else. The Boeing 787 is made mostly of carbon fiber reinforced epoxy resin.
This speaker and the writing and animations are all amazing on this!
Firemen use standpipes to fight fires in high rise. Standpipes are usually located on the stairwells. They connect and set up on the floor below the fire and then go
"Ben i wanna say one word to you , just one word . Plastics! "
We learned polymers today in class. I got confused. You uploaded a video on the same. I got even more confused. CONFUSION: 100.
Lol
At least no exploding 8 ball XD
Love you. This is amazing!
thx I've learned a lot today
Best nerds on youtube love the work done here
Thank you for your hard working:)
great work...
I will never look at polymers the same.
Great video love you ❤️
You can work and research polymer materials following the career of Chemical or Mechanical Engineering (first is more the chemistry and production; second is their mechanical properties).
Can't wait to refer to the PVC at work as a "cylindrical tube of polyvinylchloride". That'll teach those construction contractors to talk down to retail associates at home improvement stores.
awesome.thnx
0:41 No, my first response is to look for a fire alarm and get out. I'll only call the fire department once I'm safely outside.
This was awesome and very informative.
Maybe a interesting fact. Polymers like polyethylene is one of the biggest consumers of raw sugar. I have worked at a factory that makes the raw materials for plastics. (DOW Chemical)
Great and interesting video, as always
Very important lesson. Especially since I’m back in physics and engineering is a big part of it
How is there no explosive billiard video game? I need this in my life
Can you please elaborate how concentrating a moving fluid could reduce friction by upto 80% ?
That whole thread about polymers and the fire fighters was... a stretch.
Once around here an ink factory was on fire it took about 10 fire trucks and three refill dosers plus the HVAC system and all the fire extinguishers that can get their hands on to put it out
First time I watched this video I went to warch the entire Chemistry CrashCourse.
TIL: Plastic...it's how you save Sir Mixalot from a 12th floor fire @ 7:55
Is there a series on accounting on the way? Asking cos I have an exam soon lol
Just a great channel! I'm glad this stuff exists on a large platform like TH-cam :)
Video on concrete please ❤️ or reinforced concrete
hey, you guy should do a video on recycling and if doing so is really helping the earth. I want to know if I should start recycling more often and if that will help thefuture people by not using plastic bottles and using reusable containers actually helps. I feel like I am doing a good thing but I don't know if just a small about of people recycling and making an effort will actually help the world in the long run. I know that keeping the oceans clean as helping the sea life live a better life but is it helping humans live a better life by not using straws anymore, and reusing plastics?
I like the cool slime! Very appropriate for Halloween. :)
Would rigid PVC be vulcanized flexible PVC
Hi, i want to self educate myself can u please tell me is there a free or low cost "mother library" so to speak that have access of all the databases in the world and can let me access of any textbook, journal, manuscript, newspaper, novel or any piece of writing of any and every field. Im still researching and understanding what is and how databases works to self educate myself, thank you.
3:01 me watching this channel
culwin Calvin and Hobbes rocks!!!
She just said that we can make slime as a experiment. Absolute god. 👌🏻
Polystyrene is also really common - it's commonly puffed up and used as styrofoam.
4:38 when you apply conservation of momentum and end up with extra kinetic energy
The thumb on the vulcan@2:45 looks like a pinky finger, so for a while I thought he being OG and throwing up the Westside.
Amazing everything i loved it
i did the "rubber ball" experiment and ended up with slime
Wow I never thought engineering was so complex keep it up crash course!
WOA I learned this in science today..ironic?
Yikes ... SAT ON Saturday , WTF am I doing here?
Are polymers biodegradable?
Depends on the polymer. Cellulose, yeah. Expanded Polystyrene (styrofoam) not so much.
Valdemar Pereira de Matos well duh, if their made from plastics and synthetic rubbers, no.
As stated above it depends. If you look at polymers as a whole most of them are not bio degradable, meaning they will return to their original parent materials. DNA is considered a natural polymer as well as tree saps used for natural rubbers. If we look at plastics though, it again depends. There are glucose driven plastics like PLA that are biodegradable, then there are some plastics that are degradable with certain conditions like UV light exposure.
Even though they aren’t biodegradable, a good portion of them can be recycled by grinding them up, melting them, and making new things from them. Similar to other materials such as metals and ceramics.
There are absolutely biodegradable plastics. Depends on what you make it out of and what you add to it. Also, sometimes nature just up and evolves a bacteria that can eat it (happened pretty recently. They found a bacteria that eats PET, which is goddamn huge news for biodegradability of plastics)
Biodegradable plastics are usually made from something besides petroleum, or designed to break apart really nicely under certain environmental conditions like Chris said.
Synthetic Rubber can mean a couple of things. We can synthesize the exact chemical natural rubber is made of, so that synthetic rubber about as degradable. There's other synthetic rubbers that are variously degradable too.
For Recycling:
There's 2 categories of polymers: Thermoplastic and Thermoset.
A lot of plastics are thermoplastic, so you can re-melt them into something else. This means you can recycle them, but every time you do you shorten/break the chains a bit and it's not as useful as fresh made stuff. Eventually it's useless.
Thermosets cross link when you process them, which basically means you turn the pellets or whatever into one single bigass molecule. They're usually stronger, but you can't re-melt them, because you can't melt a single molecule. It'll just burn or break into a different molecule. Most rubbers are thermoset, but not all. Styrofoam is a thermoset, as is PVC (the hard white plastic stuff they use for pipes).
Thanks for asking this question, and thanks for reading my answer! I appreciate the opportunity to dig up old knowledge from my university polymers classes.
Thanks for the great replies. I think it’s a fault not to refer this in the video taking in consideration the pollution problems we’re facing nowadays.
She reminds me of a real life version of Allura: beautiful, smart, and kickass!
wassup
Polymers have the problem of decay so the material is mostly good only for temporary use or parts that are meant to be replaced.
hello friends in my class
I come here by accident...
I love maths and engineering!
So what !!
🎑
First few
Firemen dont use gas masks for fire lol
10$ if she was to say “we’ve captured objective butter” 😂
By god I love it when she talks nerdy to me.
I've been pronouncing terephthalate all wrong..
we love a smart queen
I'll save you all 10 minutes, Adding a little bit of polymer (like soap) can improve the flow characteristics of water.
Echo why?
Why should we learn history???
Your very distracting, nice show
If anyone is interested in more detailed information about polymers, check out Chapter 22 of Chemistry by Zumdahl (9th Edition).
You have an english accent. Borax isnt English, its Yank. So what is the English version?
U from...
Hard to focus with a beautiful instructor with a sexy voice
You're talking too fast and with no focus. sorry but this is video is not the standard of crash course. We could just google if we want heaps of info about polymers. Your job is to get people curious and inspired to learn more about polymers, not dumping info.
a women engineer? this is crazy!!
J.W. Stillwater Old timer.
well it seems to me that she is an early retired engineer :)
Jasmin-Bergamotte Rondelliou Why? Because she can read a script? She's young to have retired..
well I why afraid she was just a host so I looked at her bio, I can't imagine how with all the education stuff she is doing she would be able to continue her engineering activities. That's why I say retired engineer. I thinks that is a beautiful irony in fact, "We need more female role models" everybody screams. Sure, so the consequence is your are taking women from engineering to eduction, long live the stereotypes !