Questions on UV curing polyester resins.
 

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

Questions on UV curing polyester resins.
 

Questions on UV curing polyester resins.
 

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.

Questions on UV curing polyester resins.
 

On Tue, 16 Mar 2010 01:35:54 -0700 (PDT), 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.


I believe that any of the polymer based resins will destroy
polystyrene foam. At least that was what I was told years ago, but I
must admit that I never tested it.

By the way, UV curing polyester is not essentially a different resin.
It is polyester resin with a UV catalyst added to it and it is the
resin that attacks the foam.

I'm not a board builder but I believe that the polyester boards are
made using polyurethane foam.

Have a look at
http://www.compositesworld.com/artic...s-demonstrated

for more details of using UV polyester

It apparently is possible to laminate carbon fiber with some cautions.

What are you building?

Cheers,

Bruce

Questions on UV curing polyester resins.
 

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
in cooler temps.

paul oman - progressive epoxy polymers inc

More importantly, it means crosslinks between molecules, as when parts
a and b or their reaction intermediates have more than two reaction
sites per molecule. This leads to a network molecule with no melting
point, although it will decompose with enough heat. I made a variety
of thermoplastics (more or less linear molecules) using epoxy and a
reactant in my old r&d job.

Pete Keillor

Questions on UV curing polyester resins.
 

On Mar 16, 5:31*am, Bruce wrote:
On Tue, 16 Mar 2010 01:35:54 -0700 (PDT), 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.


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.

I believe that any of the polymer based resins will destroy
polystyrene foam. ...

Yes, that is correct.


By the way, UV curing polyester is not essentially a different resin.
It is polyester resin with a UV catalyst added to it and it is the
resin that attacks the foam.

Good to know.


I'm not a board builder but I believe that the polyester boards are
made using polyurethane foam.

It is quite correct that polyester and epoxy resins, mineral spirits,
gasoline and
various other solvents do not attack urethane foams the way they do
styrene
foams.

Some epoxies (e.g. WEST system) attack polystyrene. Most do not.


Have a look athttp://www.compositesworld.com/articles/techonologies-for-uv-curing-o...

for more details of using UV polyester


Thanks, that answers my question.


What are you building?


I'm working on plans for a glider. I'm interested in a long working
time.

Questions on UV curing polyester resins.
 

On Mar 16, 1:42*pm, 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
in cooler temps.

That is correct. The longest working times available are only about
a hour or so though, right? Low temperatures might extend that, but
would also thicken it making it harder to get good penetration of
fabric.

Questions on UV curing polyester resins.
 

In article ,
says...

On Mar 16, 1:42*pm, 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
in cooler temps.

That is correct. The longest working times available are only about
a hour or so though, right? Low temperatures might extend that, but
would also thicken it making it harder to get good penetration of
fabric.

With respect to Paul, who spends a lot of time here on this board helping I
used to get slow cure hardener from Larry at Raka in Florida. I am not sure if
Paul has a similar option.

Did you ever say what it is you are trying to make?

Scotty from SmallBoats.com

--
Team Rowdy Mouse, Banned from the Mall for life!

Questions on UV curing polyester resins.
 

On Mar 16, 7:46*pm, I am Tosk wrote:
In article ,
says...





On Mar 16, 1:42*pm, 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
in cooler temps.

That is correct. *The longest working times available are only about
a hour or so though, right? *Low temperatures might extend that, but
would also thicken it making it harder to get good penetration of
fabric.

With respect to Paul, who spends a lot of time here on this board helping I
used to get slow cure hardener from Larry at Raka in Florida. I am not sure if
Paul has a similar option.

Did you ever say what it is you are trying to make?


I'm planning on a glider.

Questions on UV curing polyester resins.
 

On Mar 16, 7:46*pm, I am Tosk wrote:
In article ,


Did you ever say what it is you are trying to make?



I'm looking at materials and techniques that would be useful for a
homebuilt glider.

--

FF

Questions on UV curing polyester resins.
 

Fred the Red Shirt wrote:
On Mar 16, 7:46 pm, I am Tosk wrote:
In article ,


Did you ever say what it is you are trying to make?



I'm looking at materials and techniques that would be useful for a
homebuilt glider.

--

FF


I thought you have a set of Texas Parasol plans, Fred.
Light and cheap techniques there.

--

Richard Lamb
http://www.home.earthlink.net/~cavelamb/

Questions on UV curing polyester resins.
 

On Mar 19, 3:53*pm, cavelamb wrote:
Fred the Red Shirt wrote:

On Mar 16, 7:46 pm, I am Tosk wrote:
In article ,

Did you ever say what it is you are trying to make?

I'm looking at materials and techniques that would be useful for a
homebuilt glider.
...

I thought you have a set of Texas Parasol plans, Fred.
Light and cheap techniques there.


Yes I do and have found no better (where 'better' is defined
in terms of strong, light, fast, and not too expensive) way
to make a fuselage.

I think with composites I can make a lighter wing, considering
that a glider wing will be longer, thinner and have a shorter
chord than the TP wing.

--

FF

Questions on UV curing polyester resins.
 

Fred the Red Shirt wrote:
On Mar 19, 3:53 pm, cavelamb wrote:
Fred the Red Shirt wrote:

On Mar 16, 7:46 pm, I am Tosk wrote:
In article ,
Did you ever say what it is you are trying to make?
I'm looking at materials and techniques that would be useful for a
homebuilt glider.
...

I thought you have a set of Texas Parasol plans, Fred.
Light and cheap techniques there.


Yes I do and have found no better (where 'better' is defined
in terms of strong, light, fast, and not too expensive) way
to make a fuselage.

I think with composites I can make a lighter wing, considering
that a glider wing will be longer, thinner and have a shorter
chord than the TP wing.

--

FF


The traditional primaries were quite heavy.

Think aluminum angle primary glider type fuselage and take the wing and tail
from the Texas Parasol.

The whole mess wouldn't weight 100 pounds.


--

Richard Lamb
http://www.home.earthlink.net/~cavelamb/

Questions on UV curing polyester resins.
 

No longer relevant to boat building so I've crossposted and set follow-
ups.
Thanks, r.b.b. guys!

On Mar 19, 8:55*pm, cavelamb wrote:
Fred the Red Shirt wrote:



On Mar 19, 3:53 pm, cavelamb wrote:
Fred the Red Shirt wrote:


I'm looking at materials and techniques that would be useful for a
homebuilt glider.
...

I thought you have a set of Texas Parasol plans, Fred.
Light and cheap techniques there.

Yes *I do and have found no better (where 'better' is defined
in terms of strong, light, fast, and not too expensive) way
to make a fuselage.

I think with composites I can make a lighter wing, considering
that a glider wing will be longer, thinner and have a shorter
chord than the TP wing.

--

FF

The traditional primaries were quite heavy.

Think aluminum angle primary glider type fuselage and take the wing and tail
from the Texas Parasol.

The whole mess wouldn't weight 100 pounds.


Cool! It needs to be under 150 to qualify as a FAR 103 UL glider.

How much does one TP wing weigh? How much does the
whole plane weigh, sans engine?

A 12' SkyPup wing with a 52" chord and weighs about 26 pounds,
but that has no drag spar or ailerons. The whole Pup weighs 205
lbs.

--

FF

Questions on UV curing polyester resins.
 

In article ,
says...

On Mar 16, 7:46*pm, I am Tosk wrote:
In article ,


Did you ever say what it is you are trying to make?



I'm looking at materials and techniques that would be useful for a
homebuilt glider.

Sounds like a blast. Are you starting from some plans or are you designing from
scratch? I may have missed it before but what materials are you going to use
for stringers and fabric?

Scotty

--
Rowdy Mouse Racing, no crybabies!

Questions on UV curing polyester resins.
 

No longer talking boats so I've crossposted and set follow-ups
accordingly.

On Mar 20, 12:17*pm, I am Tosk
wrote:
In article ,
says...



On Mar 16, 7:46*pm, I am Tosk wrote:
In article ,

Did you ever say what it is you are trying to make?

I'm looking at materials and techniques that would be useful for a
homebuilt glider.

Sounds like a blast. Are you starting from some plans or are you designing from
scratch? I may have missed it before but what materials are you going to use
for stringers and fabric?


Designing pretty much from scratch. My inspiration is Mike Sandlin's
airchairs. But also check out the ULF - 1.

As for materials -- that's what I'm exploring now. At preset I favor
a
dacron fabric covered riveted aluminum frame for the fuselage (Like
the
Texas Parasol) and fabric covered composite wings like the UL SkyPup,
substituting carbon fiber tapes and rod for the spar and rib caps.

I suppose if I wind up cobbling something together from diverse
sources
I should call it the Frankenglider.

--

FF

Questions on UV curing polyester resins.
 

In article , keillorp135
@chartermi.net 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
in cooler temps.

paul oman - progressive epoxy polymers inc

More importantly, it means crosslinks between molecules, as when parts
a and b or their reaction intermediates have more than two reaction

That's a bit beyond my area of expertise, but are you saying Epoxy that
is mixed more perfectly, has more heat resistance? At least that is what
I am getting from your post.

Scotty

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

Questions on UV curing polyester resins.
 

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
in cooler temps.

paul oman - progressive epoxy polymers inc

More importantly, it means crosslinks between molecules, as when parts
a and b or their reaction intermediates have more than two reaction

That's a bit beyond my area of expertise, but are you saying Epoxy that
is mixed more perfectly, has more heat resistance? At least that is what
I am getting from your post.

Scotty

I was just saying that "thermoset" refers to a crosslinked resin,
which epoxy may or may not result in, depending on the hardener.
Actually, epoxy is a reactant, there ain't any left in the finished
product. Most epoxies are dgeba (diglycidyl ether of bisphenol A)
with various oligomer mixes left in. Commonly reacted with various
high functional amines to make thermosets. I also reacted epoxies
with difunctional amines and various difunctional organic acids to
make a bunch of different thermoplastics.

Heat resistance is partially related to crosslink density (affects Tg)
but more related to the backbone molecule. Bisphenol A based resins
generally had a Tg around 100 C. Novolac and resorcinol based resins,
etc. could be higher. All of it gives up under enough heat to destroy
the chemical bonds in the backbone. That's why I used fluidized bed
burnouts to clean dies and stuff. Nothing I made would stand 900 C.

None of this is important to boat building. The very high temp resins
are way too expensive, and were developed primarily for use in
aerospace. Garden variety epoxy has plenty of temperature capability
for boats.

Getting the mix right does directly affect crosslink density, and is
important in developing the correct properties of the resulting resin
matrix.

Questions on UV curing polyester resins.
 

In article , keillorp135
@chartermi.net 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)?

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

Questions on UV curing polyester resins.
 

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

Questions on UV curing polyester resins.
 

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

Questions on UV curing polyester resins.
 

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

Questions on UV curing polyester resins.
 

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

Questions on UV curing polyester resins.
 

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

Questions on UV curing polyester resins.
 

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

Questions on UV curing polyester resins.
 

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

Questions on UV curing polyester resins.
 

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