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학습트랜스크립트
00:00OK, let's move to the polymer additives.
00:06There are many different kinds of additives to every kind of material in society.
00:16I don't think that's the kind of society, but a variety of any material may require
00:26some additives for tailoring the material itself.
00:38So here polymer additives improve mechanical properties and processability and durability.
00:47That's what really the polymers are needing.
00:51For example, the polymer is not the material which has very high young modulus.
01:01But if we add something inside, then that may increase or reinforce the polymers properties
01:10and the moving toward to a little bit the metallic compound.
01:21Sometimes reinforcement raises stiffness and strength and sometimes thermal stability too.
01:32And those examples include some glass fibers and mineral fillers too.
01:38But here in textbook, the fillers added to improve tensile strength.
01:47You should know what tensile strength is by now and abrasion and abrasion resistance and
01:54toughness and the decrease cost or it can lower the cost too because we can use it for longer
02:03time.
02:04In the previous class, I mentioned one thing like a polybutadian and polystyrene.
02:13They can collaborate to reinforce the tires, the abrasion resistance.
02:21But in that case, they are not additive to each other because the amount of polybutadian and polystyrene,
02:31almost the same or the ratio can be changed a little bit.
02:37When we say like additive, that's in semiconductor physics.
02:46Maybe that's like a docent or something, right?
02:49Here if we say something as an additive, it's not like a major material in that class.
02:59So we add a very small amount and then we get some effect.
03:05So that small amount is enough to affect the polymers characteristics.
03:11And also like a plasticizer, the word itself gives some hint, right?
03:18Plasticize.
03:19So it makes the polymer as a plastic.
03:23So add it to reduce the glass transition temperature.
03:27I think you already know the word like glass transition temperature.
03:32That's what I just explained in the previous class.
03:35And that's Tg, that's different from Tm, right?
03:39Tm is actually melting.
03:42So like amorphous region and crystalline region, they are all melting away.
03:47That's like the Tm.
03:49But in the case of Tg, only that like the amorphous region is the trying to become a liquid
03:59or some moving around by the temperature energy.
04:07And below room temperature, if Tg is lowered, that means it can be a little bit moving, right?
04:21So let's say if Tg is 50 or Tg is 20, hot summer Tg, if this polymer A and B, polymer A is still very stiff in summer
04:39because in summer temperature is around like 30 or 40 this day, so the A can survive.
04:48That it doesn't show any plasticity or the melting phenomena or anything.
04:57But in the case of B, in the summertime, they will be very soft, right?
05:04They will become very soft.
05:10You can easily fold it and flexible.
05:17So the temperature is quite important.
05:22These materials are very sensitive to the season, right?
05:26But A is not that much sensitive, but B is quite sensitive.
05:30So, you know, these say that Samsung, they are making some flip phone or fold phone.
05:43I don't think they are actually, that's really like a glass one.
05:49So they may have some plastic on the surface too.
05:55So if we go to the low temperature in the winter, it might have the higher possibility to break down or not working properly.
06:12So if we go to improve that or to lower that kind of a situation, then we may add some plasticizer to that polymer material.
06:26Normally that helps like the presence of plasticizer transform brittle polymer.
06:32So that's what I wanted to mention before.
06:36In the winter, most polymer becomes quite brittle.
06:39But if we increase the temperature in the summer, they are melting away, right?
06:45Sometimes when you touch the polymer, they already have some sticky liquid-like something on the surface, if that's quite cheap one.
06:58So that's the one.
07:00And then if this plasticizer makes that brittle polymer to a ductile polymer, right?
07:09And then commonly added to the PVC, otherwise it is very brittle.
07:14So it says like a PVC is quite brittle.
07:17And then if we have this plasticizer inside, that PVC could be a little bit flexible too.
07:25PVC is not the only one which is brittle, like a polyurethane and I'm not good at all these polymers yet.
07:36But the PMMA is also a little bit brittle at low temperature, but I don't think the PMMA is a thermal set.
07:46It's a thermal plastic.
07:49So the one thing, I think that like, what is that, like, 3-crysale phosphate compound is considered as a plasticizer.
08:04The phosphate compound plays a very important role in organic compounds.
08:10For example, that is also very important additive to what is that, the some sanitizer, also the soap, the laundry soap.
08:31So all the time, they added the phosphate compound to control the water quality and also the some other washing skill.
08:48But now the phosphate compound is prohibited for the environmental problem.
08:56So whenever you see some phosphate compound, you have to see what's the environmental effect or our body effect for that compound.
09:11Not all the phosphate is dangerous for us because, you know, like our DNA or some ATP, those energetic materials are also connected to phosphate.
09:25So the phosphate itself is not that bad for our body or environment, but some phosphate compounds are quite toxic and risky.
09:41Okay, and also there are some other kinds of the additives.
09:46Now, this is quite, might be important, right?
09:50Like antioxidants and the UV protectants.
09:54You know, the most of the organic compounds are very sensitive to UV light, right?
10:00Do you remember, all the light has three different categories, UV and visible and then IR.
10:09Normally visible make some transition of the electron inside the bond.
10:18And then in the case of IR, they are just shaking the bonds.
10:22So IR normally result in some heat, right?
10:28So we use that infrared infrared, you know, when you go to the hospital, I don't know you have that experience.
10:37But some doctors give some prescription to stay under that infrared light to warm up your body and then give some relaxation on your muscle.
10:54That's infrared infrared light.
10:57In the case of infrared, that's just heat.
11:02So this should be moving out of the Earth.
11:07That's the problem, right?
11:08That's just heat.
11:09And visible is the transition inside the molecule.
11:14So it makes a little bit higher heat too, but it does not make any bond break or something.
11:24But in the case of ultraviolet, that's quite toxic or risky for our skin too.
11:35Because our skin, our body surface is also organic compound, right?
11:41And then that organic compounds are not surviving under the condition of ultraviolet light.
11:50It's like a highest energy.
11:53The highest energy may break down the organic compound bonds.
12:01So without it, normally the, let's say, you know, you already know about the band gap.
12:10For example, 3 electron volts or 4 electron volts, but they are already like a ultraviolet region.
12:19But this is corresponding, one electron volt is like over 10,000 Kelvin, right?
12:28That's over 10,000, like 11 something, almost 12 could be a thousand Kelvin.
12:37That's very high temperature.
12:39So the ultraviolet is breaking the bonds.
12:44So if we have some UV-protecting material on the surface or inside the material,
12:52that may increase the lifetime of that polymer material.
12:58So that may cause like a slow degradation, right?
13:07The heat stabilizers too.
13:10And some lubricants added to allow easier processing.
13:18And otherwise it stick to the some duct or some root.
13:29So they cannot slide out through the dies easily.
13:34So they have to stay there.
13:36Like, do you remember this sodium sterate?
13:39If you took any of my classes and then you may remember this one, like a sodium sterate, that's kind of a soap material, right?
13:50So they are adding small amount of soap to make it very lubricant.
13:56Also colorant to make some colors, dyes and pigments.
14:02Then also maybe they can have some flame retardants.
14:09Normally flame and then the explosion, they are occurring through the radical reaction.
14:18So if we can remove or scavenge some of those radicals, they may retard.
14:30Retard means it's making slow delay something, right?
14:36So if we have some chlorine compound and fluorine compound and bottom compound,
14:41they are normally accepting the radicals and holding it for a while.
14:46So then we can add a small amount of this.
14:51But you know, like chlorine, in the case of chlorine, under the heat, the high temperature fire,
14:57they are making some hydrocarbon, this hydrocarbon and then this chlorine.
15:04See, if we make it, that becomes hydrogen-chloric acid.
15:09The hydrogen-chloric acid is a strong acid if we have a lot of things in the water.
15:18But you know, if this is the fire case, so this gas will go into our inhalation organ,
15:31then they will kill some lung cells and any other organs in our body.
15:49So that's quite the toxic one too, HF2.
15:55So they can retard the fire, but the resulting gas is also bad.
16:03So they do not add a lot of this compound inside.
16:08They are adding very small amount to retard it.
16:11That's the purpose.
16:15So like design involves some kind of a trade-off, like pesticides improve flexibility,
16:22but can reduce some strength and also they can just migrate because they are soft now.
16:32But the fillers increase the stiffness but may reduce the impact, toughness or clarity too.
16:41So we have to choose which one we need to emphasize for a specific purpose.
16:49Stabilizers protect during service and then processing, but can affect color and some cost too.
17:04Additive selection must match the application's mechanical target,
17:11where you are going to use and then what kind of purpose is required.
17:17And also like the processing of plastics.
17:24From now on, I will give you a few processing methods.
17:30Once you see that figure, that may already give you most of the information about the process.
17:40So here, let's say the processing transforms polymer pellets or resin into final shapes for some purpose.
17:56And then also that will determine the crystallinity and then also residual stress, almost everything.
18:05Okay, in the case of thermoplastic can be reversibly cooled or reheated or recycled.
18:13That's thermoplastic.
18:15So if we say thermoplastic, they can be used again.
18:23The plastic, the word itself is very confusing because when we say plastic, that's permanent.
18:29It's not moving at all for the characterization part.
18:33But here, like a thermoplastic means it can be recycled.
18:39And that's different words toward thermoset.
18:44But thermoset is like a more clear word.
18:48Once you hear that word, like it's a set, right?
18:51So we cannot change the form.
18:53It's like a thermoset.
18:55The heat until soft, and then shape as desired, then just cool.
19:02Polyethylene, polypropylene, and polystyrene, they always say thermoplastic.
19:08But in the case of like a polystyrene, the, I don't know, it's just thermoplastic, but it's very rigid.
19:17And then it's not that much soft for some purpose, depending on the molecular weight too.
19:24So it's very hard to tell.
19:26So in the case of polymer, we cannot just simply think some polymer is some kind of characteristic.
19:36Like polyethylene is soft or polyethylene is hard or something.
19:47Depending on the molecular weight or some additives, the characteristics can be changed.
19:55But in the case of thermoset, in that case, it's very difficult to control their properties.
20:02It's set.
20:04When heated from the low temperature to high temperature, that forms a molecular network.
20:11And that's a chemical reaction.
20:14You know, we already saw like a small amount of connection or the cross-linking may help the polymer for the, what is that?
20:25The rubbery condition.
20:29But if we have too much in that polymer material that will hold the material itself.
20:37So it cannot be stretched and it cannot be changed in their shape.
20:44And also it degrades when we heat it.
20:47It doesn't go to the thermoplastic way again.
20:52A polymer molded into the desired shape.
20:57And I will show you this one in the next slide.
21:00The example is polyurethane and epoxy.
21:04I think the, in the graduate school or the, for the master degree or the PhD degree in the lab experience,
21:14you may see the urethane or epoxy many times.
21:20That's the sum of that.
21:22We add something and then once it's set, that's set.
21:25Okay, here's the first one, processing plastic.
21:32I don't think you, you are interested in all these like parts name.
21:38And then you see like heat and cooling, that's quite obvious.
21:42We increase the temperature and then place some polymers with the additive, whatever we need.
21:51Some, if we have, want to have some co-polymer, then that can be used for pallet here.
21:57And then place them at a certain, the shaped where, the location.
22:05And then just press it to make the shape.
22:08This is not only for this, like a plastic one.
22:12You know, a lot of the, the, the pan or the cooking ware.
22:19They are made by this way too, right?
22:22So just the, prepare the mold and then prepare the materials inside.
22:28And then if needed, we can increase the temperature and just press.
22:33That's the compression, compression molding.
22:36That's one of the easiest way.
22:38And then the second one is the injection molding.
22:42Injection molding.
22:43You know, the word injection means like something pushing out, right?
22:49So here the, the figure gives any, most of the, the, the process way.
22:56So the, it's called the RAM.
23:01And then it says like a hydraulic pressure is given this way.
23:07And then if needed some feed, the, the polymer pallet, then you can go back and then put some polymers inside.
23:15And then that, that's called like a barrel.
23:18And then increase the temperature by this, this one or some, this is a heating chamber.
23:26And then that's a spread.
23:28So the, the polymer can move towards, through this, this way.
23:33And then that's kind of the spread way.
23:36Otherwise they will just, um, the collect, uh, or coagulate and then stay that way.
23:44So just pushing away to go to this mold cavity.
23:49And then lower the temperature and take that out.
23:53And that's it.
23:55Injection.
23:57Injection is kind of, um, the liquid can be injected to a mold.
24:04So, um, the, the first one is just a pressing and then the molding.
24:10And then the third one is, uh, almost the same way to the second one.
24:15But here, like a feed hopper is like providing all the time in the, in the previous one.
24:22And then you remember that a ram can be moved from the, toward or backward, the, to, um, put the, uh, uh, the polymer pellet.
24:35But in this case, if we move, moves this, uh, screw, right?
24:41This screw can move that the plastic pellet into the heating part.
24:47And then finally the shaping, the die is existing.
24:51And then the extrusion, it's like pushing out.
24:56Almost the same to the injection, right?
24:58But the way is a little bit different.
25:01So, um, maybe you can make your own, but I don't think we, uh, we have only this kind of, uh, the processing weight.
25:11Whatever you want to, um, modify, that might be enough.
25:16And then the last one is like, uh, the blown film extrusion.
25:22So, uh, this part is the same as the previous one.
25:26And then it says it has, uh, uh, like a tubing die, tubing dies here.
25:32And then also, uh, I, I, I thought there is some word saying, uh, um, annual, annual tube.
25:42This is the annual tube.
25:44So, uh, the annual tube is located inside.
25:48And then the polymer liquid or, uh, the melting, melted polymer will move out to this way.
25:57And then that becomes like a balloon type, right?
26:01Because air, air is moving to this way too.
26:04So inside, this should be empty.
26:07And then this thin, uh, very thin polymer layer can be,
26:13uh, added to this, like a pinch rolls.
26:17And then they can, uh, the, by pressing with some temperature,
26:23they can make some, this flat film.
26:26You know, by the time of this way, but still it's not flat at all.
26:32It's like a round shape.
26:34It, it's curved.
26:35But once it goes through this, like a rolls, and then that becomes a flat.
26:42And then becomes some, this a film type or sheet type or whatever.
26:47Okay.
26:48Uh, that's the way we can do some, uh, processing.
26:54So, uh, I don't know you are interested in that kind of, uh, the polymer processing type.
27:01So, um, a lot of companies are doing, having that kind of, uh, processing the equipment to make all this, the plastic material.
27:13For example, the bowel, if you go to any snack bar or any snack store,
27:22then they have some plastic, the, uh, dish or the, the bowel too, right?
27:30All those, uh, the plastic materials are made by that way.
27:35Okay.
27:39And then polymer types, uh, fiber, fiber, you know, what fiber is, uh, it's, it's a regular fiber one.
27:46And then length and diameter is, uh, greater than, uh, the, you know, this is the diameter.
27:55And then length is this way.
27:57The ratio is over a hundred and that's called like fiber.
28:01And then sometimes we can have a bunch of, uh, these fibers that can be used to, uh, deliver the light through the fiber to the other side.
28:14So that might be very fast to deliver the, some, the signal to, from one side to the other.
28:21And then primary use in, uh, textile.
28:25That's our clothes or, uh, any kind of the, uh, textile.
28:32Sorry.
28:33The fiber crystallistic high tensile strength.
28:38Then high degrees of crystallinity and structures containing the polar groups.
28:44Um, I don't know, they should have this kind of polar group to make this like a fiber.
28:52Uh, I think this can be, uh, made through the, some shape or, uh, if we go back this way, I don't think this extrusion, the way is good for the fibering.
29:09If we, if we, if we would like to make the fiber through this way, then we cannot go through this way.
29:15And then it should be, what is that, like a twisted to make some, the, the rope shape.
29:22And then, uh, maybe heat treatment again, or, uh, push the, the tensile strength to stretch out.
29:32Or, uh, maybe this could be good one too.
29:36If we have like a very, the small hole, that extrusion, extrusion.
29:42In this case, if we, uh, here, you're, you're already like tubing and pipes, or if that's very thin, that becomes a kind of a fiber.
29:55And then, uh, the spinning, uh, the spinning is almost the same as like an extrusion.
30:02But, uh, in the case of, but the smaller scale and, um, some, some sort of a moving way.
30:12Actually, the top part is moving.
30:15So, uh, if it goes this way and then it has like a water or like a cooling material inside.
30:22So, um, it's, uh, you know, in Korean, the, the traditional food, 가래 떡, that's coming out like a spinning or extrusion.
30:35Okay.
30:36Then here, it says, like, it says spinning, but here extrude polymer through a spin and narrate.
30:43Very small, uh, orifices.
30:47The spun, spun is like a push, push it out, right?
30:52The fibers are drawn on the tension to make it this long, the fiber.
31:00Highly, highly aligned chains and fibrillar structure.
31:06And also miscellaneous, some other times.
31:10That's good word, right?
31:12The, we explain something, but others are all miscellaneous.
31:16The coatings and thin, the polymer films applied to surface and paints and then varnishes.
31:25And protects from corrosion and degradation.
31:28And, uh, decorative improve appearance.
31:32And can provide electrical insulation.
31:35And also adhesive, that's bond, right?
31:39So, uh, the bonds to, uh, two solid materials.
31:44Then bonding types is secondary, banderabite sporeses, and mechanical penetration into, for the pores and crevices.
31:52So, uh, most bonding is this way.
31:56But some of them is, uh, this way too.
31:59So, we have materials A and B, A and B.
32:04If we take a look at detail on the surface.
32:08A surface is this way.
32:14B surface is also.
32:16Okay.
32:17Okay.
32:18Then this, like, uh, the adhesive can go into all this, the gap side.
32:28And then hold A and B up and down.
32:31That's a mechanical ray bonding type.
32:34Or, if we put, uh, place them here.
32:37It doesn't mean, it doesn't need to be, the surface doesn't need to be, uh, the 3D.
32:44It doesn't need to be flat or it doesn't have to be, uh, it doesn't have to have like a pores or anything for the secondary.
32:54But in the case of a Kennedy, that's required.
32:57If they have very flat, it's not gonna work.
33:02And the film and foams, gas bubbles into plastic.
33:07You already saw them many times.
33:09Like, uh, what is that?
33:11If you order some food, the cold food or the frozen food, the container is kind of like a bubbled plastic, right?
33:23And then advanced polymers.
33:28So the polymer, uh, the high quality polymer is, can replace a lot of things because the, our body is also organic compound.
33:39So, uh, if we can have some organic compound for our body parts, then might be very, um, what is that?
33:49The good for each other.
33:52Then, um, they do not repel each other.
33:58So, um, but for that purpose, uh, the, it needs a lot of the requirement such as, uh, it, it, it, it, it shouldn't show some, the stick problem for the, for the, the protein.
34:15If protein, uh, protein gathers at the surface and then they stay there, um, then, then may, uh, affect some other side effect or causes some other disease or something.
34:30So here, ultra high molecular weight polyethylene.
34:36So polyethylene is the basic material.
34:39And then that has been researched for, uh, from the very basic polymer discovery.
34:45So currently if we have like a very high molecular weight of this one, you can guess how many ethylene can be, uh, should be connected to make this kind of molecular weight.
34:59And then, uh, it says like high impact strings and also resistance to wear and abrasion and low coefficient of friction and self lubricating the surface.
35:12And, uh, the bulletproof.
35:14Oh, that's quite, uh, important, right?
35:18The high molecular weight that protects the bullet.
35:23That's quite interesting.
35:25You know, I, I know like one polymer, like a Kevlar, that's, uh, the brand name, not a polymer name.
35:32The Kevlar can also protect the bullet.
35:36Uh, I don't know what the, the actual, the, the molecular mass of the Kevlar or what kind of polymer it is.
35:53It is in the, in elemental way, but that's one of the interesting.
35:59And then golf ball covers.
36:01Um, that's interesting.
36:04Like, I know like a, when, when we do some, when we play golf, I don't play golf, but when we play golf, the, what is it called?
36:15Like a, some smashing.
36:19If we do some smashing on this golf ball, the impact might be very high.
36:25So it may be broken down by just one hit or two, a few times.
36:33So, um, if it can be covered by this kind of polymer material, then the, the ball can survive.
36:43And also it has some, the high flexibility.
36:46That might be a good way.
36:48And then hip, hip implants.
36:51That's the one, the textbook mentions a lot.
36:55The, at the very beginning of the, the textbook, they also had like a, the cover image of this ultra high molecular weight polyanthaline uses.
37:06Can you guess if this could go to your, not, I'm sorry, they get somebody's leg.
37:17And also like advanced polymer, thermoplastic, the elastomer.
37:22I already mentioned that like a styrene and butadian block or polymer.
37:26No, it's not just simply mixing them.
37:30When we synthesize this styrene and butadian is all added up together.
37:37Then by controlling temperature or initiator, whatever we have, by controlling them, then they can synthesize this kind of a polymer.
37:49And then they are saying like, the connection part is quite important.
37:54So the soft components domain is for butadian.
38:00And then hard components is for the, this styrene part.
38:07But actually they are not connected to each other.
38:11Okay.
38:12I think I mentioned a lot of things in this chapter too.
38:19I really want you to understand the basic concept for that.
38:27The detailed one, the word itself might be quite confusing.
38:32I'm not asking you to remember all those words.
38:35The, some of the, but for the better communication, if you have like a, if you read the questions
38:46to understand the question clearly, you may need to understand the words or terms clearly.
38:52Otherwise, you may not answer the question correctly.
38:56Okay.
38:57So here we have a lot of the, some like the, the terms, elastomers, thermosets, thermoplastics,
39:07and then some examples.
39:09Then I think you, you, some of them still stay in your brain.
39:18And then also polymer processing, that was quite easy.
39:23And then application could be many things.
39:29Okay.
39:31Here is the, the summary for the, this chapter.
39:36So that might be it.
39:38We will go for the other topics in the next recording.
39:43Thank you.
39:45Thank you.
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