In article , keillorp135
@chartermi.net says...

On Sun, 21 Mar 2010 17:16:00 -0400, I am Tosk
wrote:

In article , keillorp135
says...

On Sun, 21 Mar 2010 12:10:58 -0400,
wrote:

In article , keillorp135
says...

On Tue, 16 Mar 2010 13:42:41 -0400, Paul Oman
wrote:

wrote:
On Mar 14, 12:31 pm, Paul Oman wrote:

wrote:

Two questions for people with knowledge or experience with the UV
curing polyester resins:

1) Are they (any of them) compatible with polystyrene foam?

2) Once the UV light has initiated the polymerization, will it spread
through the layup even into places where the light did not
penetrate? I'm thinking, for instance about the underside
of carbon fiber cloth.

Thanks.

--

FF

it makes more sense to use thermo set epoxies. Stronger, better bond,
probably cheaper.
epoxies will not dissolve foam


Thermo set meaning that they don't begin to cure until they are
heated?
I ask because I am looking for a very long working time.

If so, do you have a recommendation?

Otherwise, can you answer the first question? I was quite aware of
the
other issues.

----------------------
thermo set means a chemical reaction between parts a and b and these
reactions produce heat. This is how epoxies work. You can get slow
epoxy curing agents and you can also slow down the reaction by working

I think I get it. In simple terms can I assume parts or molecules of
resin that are not activated by the correct molecules of activator, will
just stay resin and never really "harden" (for lack of a better term)?

Pretty much. More likely, the molecule would be reacted on one end
and not the other. Reaction kinetics will usually favor one end
reacting first. The end result is lower crosslink density, unreacted
groups, and less than full development of cured properties.

Pete Keillor

Good... In a simpler way, that is the way I understood it. Thanks for
the info, and patience

Scotty

--
For a great time, go here first... http://tinyurl.com/ygqxs5v

On Sun, 21 Mar 2010 18:43:06 -0400, I am Tosk
wrote:

In article , keillorp135
says...

On Sun, 21 Mar 2010 17:16:00 -0400, I am Tosk
wrote:

In article , keillorp135
says...

On Sun, 21 Mar 2010 12:10:58 -0400,
wrote:

In article , keillorp135
says...

On Tue, 16 Mar 2010 13:42:41 -0400, Paul Oman
wrote:

wrote:
On Mar 14, 12:31 pm, Paul Oman wrote:

wrote:

Two questions for people with knowledge or experience with the UV
curing polyester resins:

1) Are they (any of them) compatible with polystyrene foam?

2) Once the UV light has initiated the polymerization, will it spread
through the layup even into places where the light did not
penetrate? I'm thinking, for instance about the underside
of carbon fiber cloth.

Thanks.

--

FF

it makes more sense to use thermo set epoxies. Stronger, better bond,
probably cheaper.
epoxies will not dissolve foam


Thermo set meaning that they don't begin to cure until they are
heated?
I ask because I am looking for a very long working time.

If so, do you have a recommendation?

Otherwise, can you answer the first question? I was quite aware of
the
other issues.

----------------------
thermo set means a chemical reaction between parts a and b and these
reactions produce heat. This is how epoxies work. You can get slow
epoxy curing agents and you can also slow down the reaction by working

I think I get it. In simple terms can I assume parts or molecules of
resin that are not activated by the correct molecules of activator, will
just stay resin and never really "harden" (for lack of a better term)?

Pretty much. More likely, the molecule would be reacted on one end
and not the other. Reaction kinetics will usually favor one end
reacting first. The end result is lower crosslink density, unreacted
groups, and less than full development of cured properties.

Pete Keillor

Good... In a simpler way, that is the way I understood it. Thanks for
the info, and patience

Scotty

You're welcome.

Pete

On Mar 21, 6:33*pm, Pete Keillor wrote:
On Sun, 21 Mar 2010 17:16:00 -0400, I am Tosk

...

[The context here is epoxy and what happens if it is not quite
thoroughly mixed. -- FF]


I think I get it. In simple terms can I assume parts or molecules of
resin that are not activated by the correct molecules of activator, will
just stay resin and never really "harden" (for lack of a better term)?

Pretty much. *More likely, the molecule would be reacted on one end
and not the other. *Reaction kinetics will usually favor one end
reacting first. *The end result is lower crosslink density, unreacted
groups, and less than full development of cured properties.


Thanks.

The late Peter Van Dine worked almost exclusively with polyester
resin. One of the reasons he stated for his preference was that
that, in contrast to the situation described above for epoxy, once
the crosslinking was initiated it would eventually spread through
the entire matrix.

This is what led me to ask if the same was true for UV cured
polyesters.

So, I am now led to ask if he was correct.

And now we have come full circle.

--

FF

In article b949f95b-c2cb-481f-a1db-079c341bb469@
15g2000yqi.googlegroups.com, says...


This is what led me to ask if the same was true for UV cured
polyesters.

So, I am now led to ask if he was correct.

And now we have come full circle.

Sorry to have taken your thread off on a tangent Hopefully you can get
your answers now that my curiosity has been satisfied

Scotty

--
For a great time, go here first... http://tinyurl.com/ygqxs5v

On Mon, 22 Mar 2010 10:28:16 -0400, I am Tosk
wrote:

In article b949f95b-c2cb-481f-a1db-079c341bb469@
15g2000yqi.googlegroups.com, says...


This is what led me to ask if the same was true for UV cured
polyesters.

So, I am now led to ask if he was correct.

And now we have come full circle.

Sorry to have taken your thread off on a tangent Hopefully you can get
your answers now that my curiosity has been satisfied

Scotty

I never worked with the uv part. I also haven't worked with these
resins. I did work with people dealing with them in r&d. Polyester
and vinyl ester resins cure by a completely different mechanism, a
free radical chain polymerization. The reactive diluent is styrene
monomer. The reaction is inhibited by oxygen, hence the wax to exclude
air from the surface, or the use of film for vacuum bagging and resin
infusion molding.

This type of reaction is not nearly as dependent on stoichiometry
(ratio of reactants). The initiator and catalyst are all about
providing free radicals to start the polymerization. UV does the same
thing. The concentration of reactive diluent will affect final
properties. Polystyrene ain't that strong.

To the original two questions:

1. styrene monomer will dissolve polystyrene foam like there's no
tomorrow.

2. Don't know. My guess is the initial free radicals generated will
initiate the reaction, the reaction generates further free radicals,
so the parts should cure eventually. I don't know the effect of a
light blocker like carbon fiber, but the stuff would have no
commercial value if at least some useful depth wouldn't cure.

For my fishing boat, I found one using vinyl ester. It's a hell of a
lot stronger and more chemically resistant than polyester. If I build
a boat (would like to, that's why I read this group), I think it'll be
plywood and epoxy. Also, if you're interested in advanced composites,
make sure the resin you use is recommended for the reinforcement. I
recall a rubber modified vinyl ester as being the very best at wetting
Kevlar.

Good luck.

Pete Keillor

In article , keillorp135
@chartermi.net says...

On Mon, 22 Mar 2010 10:28:16 -0400, I am Tosk
wrote:

In article b949f95b-c2cb-481f-a1db-079c341bb469@
15g2000yqi.googlegroups.com, says...


This is what led me to ask if the same was true for UV cured
polyesters.

So, I am now led to ask if he was correct.

And now we have come full circle.

Sorry to have taken your thread off on a tangent Hopefully you can get
your answers now that my curiosity has been satisfied

Scotty

I never worked with the uv part. I also haven't worked with these
resins. I did work with people dealing with them in r&d. Polyester
and vinyl ester resins cure by a completely different mechanism, a
free radical chain polymerization. The reactive diluent is styrene
monomer. The reaction is inhibited by oxygen, hence the wax to exclude
air from the surface, or the use of film for vacuum bagging and resin
infusion molding.

This type of reaction is not nearly as dependent on stoichiometry
(ratio of reactants). The initiator and catalyst are all about
providing free radicals to start the polymerization. UV does the same
thing. The concentration of reactive diluent will affect final
properties. Polystyrene ain't that strong.

To the original two questions:

1. styrene monomer will dissolve polystyrene foam like there's no
tomorrow.

2. Don't know. My guess is the initial free radicals generated will
initiate the reaction, the reaction generates further free radicals,
so the parts should cure eventually. I don't know the effect of a
light blocker like carbon fiber, but the stuff would have no
commercial value if at least some useful depth wouldn't cure.

For my fishing boat, I found one using vinyl ester. It's a hell of a
lot stronger and more chemically resistant than polyester. If I build
a boat (would like to, that's why I read this group), I think it'll be
plywood and epoxy. Also, if you're interested in advanced composites,
make sure the resin you use is recommended for the reinforcement. I
recall a rubber modified vinyl ester as being the very best at wetting
Kevlar.

Good luck.

Pete Keillor

Get the book "Build the new Instant Boats" from Dynamite Payson, at
InstantBoats.com. Be sure to get the right book, the brown covered one
not the green cover, previous book simple titled "Instant Boats"
although it is a good read too for the extra few bucks. Just substitute
Epoxy for most of the stuff Dynamite talks about, it was not as easily
accessable and affordable back when the book was written. By the time
you have read it, you will be ready to build your first boat. This was
mine, from the book it's the white one in the top of the page...

http://smallboats.com/boats.htm

Dynamite is great to read, down East and with all the color of his
generation there. Anyone would enjoy this book in my opinion.

Scotty. "No man should pass until he has wet a hull of his own hand"..
(me, I don't remember the first time I said it, who knows, maybe I read
it...)

--
For a great time, go here first... http://tinyurl.com/ygqxs5v

On Mar 22, 10:28*am, I am Tosk
wrote:
In article b949f95b-c2cb-481f-a1db-079c341bb469@
15g2000yqi.googlegroups.com, says...



This is what led me to ask if the same was true for UV cured
polyesters.

So, I am now led to ask if he was correct.

And now we have come full circle.

Sorry to have taken your thread off on a tangent Hopefully you can get
your answers now that my curiosity has been satisfied

Scotty


No problems. 'twas a tangent of interest to me as well.

--

FF