Name: 晶體和非晶體聚合物 (Crystalline and amorphous polymers)
Uploaded: 2021-01-14T10:57:45.000Z
Duration: 4 min 42 s
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about crystalline and amorphous polymers.

Now, in previous videos, we talked about crystalline

Crystalline solids have a very regular pattern,

It's still solid, so these things aren't moving

past each other, like they would in a liquid,

about crystalline and amorphous solids made from polymers.

Polymers can actually exist in a spectrum

so you have a subunit, and then it's bonded

because these long strings of these repeating units

and we've talked about things like elastomers,

and become a little bit more crystalline.

For example, even with rubber, if you were to pull on it,

And then the intermolecular forces between them

because they are a little bit more aligned.

And so this form would be more crystalline,

not perfectly crystalline, but more crystalline

And to just see examples of different polymers

we have something that is very crystalline,

we can see examples from our everyday life.

for example, polystyrene, which you might be familiar

but let's say we could put it right over here.

So this is made up of polymers, repeating units,

but they're going to be fairly disordered,

and that's what gives it kind of its softness,

that's why it's good as a packaging material.

Now, if we go a little bit further down the spectrum,

you can look at things like plastic water bottles.

PET stands for polyethylene terephthalate,

anything, like polystyrene, polyethylene,

the fact that they start with the word poly

Polystyrene is made up by a bunch of styrenes in a chain.

Polyethylene is made up by a bunch of ethylenes in a chain,

and so polyethylenes, depending on which version

it's someplace between amorphous and crystalline.

For example, it might be someplace over here.

And if you wanna do further research on it,

you can actually look up how crystalline something is,

and you'll see numbers like 30%, or 40% crystallinity.

And if you wanna look at especially plastic polymers

and Kevlar, depends on the Kevlar you are looking at,

it could be someplace in this range here,

I'll just put the Kevlar right over there.

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晶體和非晶體聚合物 (Crystalline and amorphous polymers)

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