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Participant

Join Date: Nov 2008
Posts: 3

Polymerization

04/04/2010 9:29 AM

Hi everybody

I need a good reference about the reaction of polymerization. Also how can improve the properties of vinylester resin?

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Guru

Join Date: Oct 2008
Posts: 42316
Good Answers: 1666
#1

Re: Polymerization

04/04/2010 10:31 AM

This site lists a number of organizations that may be of assistance in your search.

Plastics Institute of America - Resources - Major Plastics ..

Any university will have books on the subject.

Since you don't tell us where you are, that's about it.

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Guru

Join Date: Oct 2008
Posts: 42316
Good Answers: 1666
#2

Re: Polymerization

04/04/2010 1:03 PM

This is a very easy experiment to perform and it gives you an insight into polymerization:

Video results for nylon rope trick

Also Google "nylon rope trick" for other information.

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Active Contributor

Join Date: Jul 2007
Posts: 11
#3

Re: Polymerization

04/06/2010 8:51 AM

I'm not a chemist but here's my best simple explanation of free radical chemistry: The reaction employed in vinylester curing is a free radical reaction. It's a fairly simple reaction. An initiator, typically a peroxide, breaks down and attacks reactive sites on the vinylester molecule creating free radicals. This allows a crosslinking agent (typically styrene) to react with vinylester chains, linking them together, for lack of a better word. The rate and degree of this reaction can be controlled to a certain extent by temperature.

Most vinylesters are formulated to give the users a very narrow range of properties. There are a few ways to mildly improve those properties. First off, you can try a heated post cure. If your part is small, just stick it in an oven and elevate the temp. Secondly, you can investigate different initiators. The standard for room temperature curing peroxide is MEKP. There are several others, though, that react at higher temperatures and may improve the propertise you are seeing in your vinylester. One that comes to mind is t-butyl peroxybenzoate. I've used that to cure an epoxy functionalized vinylester at 350 F and got a Tg near 280 F.

Take a look at epoxy functionalized vinylester resins with an elevated temp initiator. There are some that are very good (Derekane from Dow is a good brand).

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