[Kirst (OP)]

Hey ther budding scientists kirst here.
I am in need of another favour but for a mate this time, would any physicist be able to tell my mate the rough physical properties of paper and plastic and the physics background to the two materials. It would help them out loads if you would be able to give them a rough idea about it.
They have had extreme difficulty trying to find research from other web-sites.
Thanks so much to anyone who can help an AS student in distress!!


K.Sable

[NakedScientist]

We never did get to the bottom of this - anyone fancy a go ? Quantum cat is usually pretty good at this sort of thing !

[Quantumcat]

Oooh, I am? hehe ...

Well, plastic is made of polymers. Polymers are long long long chains of repeating molecules. Polymer materials have interesting properties ... have you ever played with that magic goo, that stretches and flows but shatters if you hit it hard? That is because when you let it flow or pull on it slowly, the long chains of molecules have time to slide past each other (think of a bowl of speghetti being tipped out onto a table) but if you hit it with a hammer, it shatters, because the molecule noodles can't get past each other time to take the impact, and break apart. That is why plastics can be bent but shatter if you snap them. Usually plastics are dry and the polymers are all but locked into place so you can't see it happening too well. Plastic polymers are usually made of poly-vinal (however you spell vinal) acetate (I think?) or PVA. If you looked on a google image search under "PVA" you might find a diagram of how it all links together, I don't know off the top of my head. But anyway, I have no idea how paper is structured. Made of plant fibres, all short and twisted round together kind of. that's why it rips easily and plastic doesn't. Anyway I don';t think I answered your question as that was about the chemical side of things .... but it took to long to type to erase it all now

[paulat]

In paper the fibrils are short and arranged in various orientations, cross-linking each other like a net. We had to tease apart paper and look at it down a microscope when I was a school. Apparently the newspaper The Sun gives the best fibres for looking at down the microscope. I suppose it's got to be good for something since, as newspapers go, it's crap.