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Specialty Chemistry Forums => Materials and Nanochemistry forum => Topic started by: samkc on December 15, 2009, 03:50:03 PM

Title: polymers
Post by: samkc on December 15, 2009, 03:50:03 PM

Hello,

I would like to know if a single solid piece of plastic such as a rod of HDPE represents a single continuous polymer chain. If not, what force keeps the rod in a single piece?

Thanks,
Sam

Title: Re: polymers
Post by: Borek on December 15, 2009, 04:16:21 PM

No, it is not a single molecule. And forces that keep it intact are exactly the same ones that keep candle in one piece, even if it is made from much shorter (albeit very chemically similar) molecules.

Title: Re: polymers
Post by: samkc on December 15, 2009, 04:45:12 PM

Thanks.

Can you tell me what type of bonds are responsible for holding the separate chains of polymers together?  I assume these are not the same covalent bonds that hold the atoms within the polymer together.

Sam

Title: Re: polymers
Post by: Borek on December 15, 2009, 06:39:30 PM

What intermolecular forces do you know? To some extent and denpding on polymer they will be all at work.

Title: Re: polymers
Post by: polymergirl on December 15, 2009, 09:31:02 PM

Most "plastics" are polymers that are long enough to be held together via chain entanglement.  The polymer chains are long enough that the are tangled up (oftten times this is described like a bowl of spaghetti).  This increases the viscosity of a polymer.  When the material is below the Glass Transition Temperature (Tg) it is then hard and generally doesn't flow.

Other factors can affect the mechanical properties such as crystallinity, chain structure, etc.

Title: Re: polymers
Post by: samkc on December 16, 2009, 10:52:40 AM

Thanks. That is a very helpful explanation.

Sam