UV Resin Curing and Shrinkage

General Discussion
21
Quote:

So what is going on?

A hot batch will heat the nearby gases and cause a predictable pressure and volume increase. And this has the capability of screwing up a finbox set or a lam if the resin is set off hot enough to cause variable expansion of the foam. Of course the foam expands when the box is setting, and then contracts and cracks as it cools, so the entire process results in a very weak set.

I’m nearly certain that the specified shrinkage in resins when curing is insignificant to cause any change in shape. Its the heat that gets ya.

Wo…just when Im starting to get it…curve ball.

22

Thanks for that great answer, native customs – super educational.

If it’s not too much of a bother, can you explain how an ordinary person like myself can identify if my MEKP is a (for example) K4CE? That one looks great – medium gel/cure times, and lowest exotherm by a lot (if I read the graph correctly).

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Glad this took off today while I was away from the computer, good stuff on those links.

I’m surprised this apparently hasn’t been discussed before. Unless the MEKP is precisely on the mfr’s ratio,

and perfectly dispersed (mixed) into the resin, UV cure has it all over cat cure. I’m so stupid I thought everyone

knew this. And most MEKP work is so over-catalyzed that the polymer chains are not nearly as complete as in

UV cure.

But the difference in finished board strength is not so great as to be a determining factor in the life of the board.

The amount and type of fiber in the laminate is far more critical. But this was initially about shrinkage, and it’s dead

certain that UV shrinks less.

Mike