Styrene evaporation

[Fellies]

Climate control
1600 M altitude, lower boiling point
20 or below humidiy.
Do i have an evaporation propblem with the styrene

 

[Fellies]

Im not sure if its my imagination anymore. Anyone working with the sters in dry climates that can help

 

[ondarvr]

High altitude and low humidity increases the evaporation rate, but it being a problem depends on some very specific aspects of your production process.

Customers at high altitude quickly become accustomed to how the resin or gel coat behaves and it isn't something they need to think much about.

 

[Fellies]

Thanks, hopefully those customers reply with there experience

 

[gonzo]

Have you had an issue? The cure time of polyester is fairly fast and not likely to cause a problem. Are you hand laminating?

 

[Fellies]

Have you had an issue? The cure time of polyester is fairly fast and not likely to cause a problem. Are you hand laminating?

Hi there,

Sometimes i get a rubbery undercure on the smaller parts i use. I put in more catalyst to try get a faster reaction as the boiling point is lower with the altitude and then find difficulties with it kicking too fast. Having more of a problem on the gelcoats, as i can infuse the skins later on which wouldnt give me the problem. Im getting that undercuring on the intitial gelcoat layer however I am brushing it on. The styrene might be evaporating from slightly thinner brush stroke over the smaller mould and going ahead I just want to make sure i get a proper cure. Im going to make a bigger mould and with a running plug so im abit nervous on the application. It would be a VE tooling gelcoat. The dryness is of course good for preventing moisture but once ive mixed it and applied the surface area is much bigger than in the bucket. On a side note ive seen it with PVA glues and veneers, the dryness dries the water out before it can saturate the wood and bond. Ive tried to find info with the suppliers and they dont slightest clue on what im even saying which is starting to make me doubt it. I thought about pulling a simple tent around the plug which is only 24 ft so it wouldnt be too big and try to create a better environment.

Almost zero boats are built in my country, especially my area so its a little nerve racking. Otherwise I will give it a bash and hope for the best

 

[gonzo]

Styrene does not affect the cure. It is a solvent used to lower the viscosity. PVA is water based and will dry faster. Are you making wooden molds and just waxing them? Usually there is fiberglass laminate and tooling gelcoat as a finish. Where are you located; do you have local suppliers?

 

[Fellies]

Styrene does not affect the cure. It is a solvent used to lower the viscosity. PVA is water based and will dry faster. Are you making wooden molds and just waxing them? Usually there is fiberglass laminate and tooling gelcoat as a finish. Where are you located; do you have local suppliers?

Styrene is what crosslinks with the polyester chain, the mekp is what activates it. Its epoxy primer used on the plug then ill wax it and a PVA. The water molecules holding the plastic flash off before it saturates the wood on that department. Just looking for expericnce at altitudes and dryness

 

[ondarvr]

While the surface of the gel coat or laminate may be slightly more tacky than at lower elevations, the cure beneath the surface should be fine. Thicker layers are less affected than thinner applications due to surface area compared to the mass.

Brushing is less affected than spraying because of the loss during atomization. Worst case scenario you could add a percent or two of Styrene to compensate for the loss. This isn't normally done though, and 1,600 meters isn't that high of an elevation, we make no alterations for gel coat or resin at that elevation.

 

[Fellies]

Thanks for the reply. Im just going to go for it. I will pull a tent and try create a styrene blanket over it. Will also put the gelcoat on thicker as these smaller tests show a problem with the humidity being under 20 and the thinner gelcoat areas are evaporating faster. The altitude definitely lowers the boiling point so i just got the keep the catalyst higher and work faster.Unfortunately, most things flash off extremely fast here, just something I have to get used to.

 

[Dave G 9N]

Ok, you seem to have a good grasp of the problem and solution.

From the description given by ondarvr, the slow cure at the surface is consistent with a loss of the catalyst due to evaporation. Styrene has a boiling point of 145°C. MEK peroxide has a boiling point of 19ºC (just the MEK peroxide, not the mixture in the catalyst solution). Due to the large difference in boiling points, the MEK peroxide is much more volatile than styrene. There is a lot of styrene, and a small amount of MEK peroxide. If anything is significantly depleted by the lower atmospheric pressure, it is the small amount of the much more volatile component. Using a hotter mix for the final coat makes sense. You need a little more catalyst to compensate for evaporation.

FWIW; Styrene is a reactive diluent, which is another way to say "Styrene is what crosslinks with the polyester chain, the mekp is what activates it." Both the styrene and unsaturated polyester resin undergo a free radical chain reaction and will react with each other forming a co-polymer.

https://www.sciencedirect.com/science/article/abs/pii/S0142941811001772
Styrene - Safety Data Sheet https://www.chemicalbook.com/msds/styrene.htm
2-Butanone peroxide - Safety Data Sheet https://www.chemicalbook.com/msds/2-Butanone-peroxide.htm

 

[Fellies]

Thanks for the reply.

im going ahead with it and will make a frame with standard drop sheeting on the side. I can control it all in there.

Ill anyways prime the resin and make a barrier coat on the first layer to get rid of some print through and shrinkage. Tent is the best option. Can also control the static air in there for most of it.

The boiling point with the extreme dryness has been solved. Many thanks. Hopefully many boats will be free of blistering

Trying to get veneer down is even harder. Another story for another day

 

[wet feet]

Living less than 10 metres above sea level means that this is a problem I have never had to consider.What I will point out is that lots of resin is used in infusion projects and the level of pressure within the vacuum bag is much lower than ambient at a moderate altitude,we don't hear of a stream of disasters.

 

[Fellies]

Thanks for the reply

After the gelcoat I would anyways mix a barrier coat and prime the first layer, and then only after that i could infuse. I for sure would not have any problem under a bag after that. Its just going a little out the way for all that work I feel. The problem starts with the gelcoat. Im going to ramp up the heat afterwards in the tent to lock it down even more as soon as ive finished the layup. Ive got major temperature difirentials on large parts ive measured. Im going to have thermal shock on the mould if i dont use a a tent or a small controlled room so it will anyways be the easiest setup. You freeze in the shade and sweat in the sun Epoxies and foam cores shine here, especially corecel, slight static issues, The crosslinked foams have an easier time with the outgassing with slightly lower exotherms and practically no moisture. There are some great benefits in that department.

Ive had change reducer for awlcraft and go much higher, water based products are disasters... flash off is definately real

 

[rxcomposite]

Hi there,

Sometimes i get a rubbery undercure on the smaller parts i use. I put in more catalyst to try get a faster reaction as the boiling point is lower with the altitude and then find difficulties with it kicking too fast. Having more of a problem on the gelcoats, as i can infuse the skins later on which wouldnt give me the problem. Im getting that undercuring on the intitial gelcoat layer however I am brushing it on. The styrene might be evaporating from slightly thinner brush stroke over the smaller mould and going ahead I just want to make sure i get a proper cure. Im going to make a bigger mould and with a running plug so im abit nervous on the application. It would be a VE tooling gelcoat. The dryness is of course good for preventing moisture but once ive mixed it and applied the surface area is much bigger than in the bucket. On a side note ive seen it with PVA glues and veneers, the dryness dries the water out before it can saturate the wood and bond. Ive tried to find info with the suppliers and they dont slightest clue on what im even saying which is starting to make me doubt it.

It is physics. If the coating is thin, it has relatively more surface area. More surface area means faster evaporation of the styrene. It is also dependent on the spray gun you are using. If it is a chop gun sprayer or gelcoat sprayer. The way it mixes after it exits the tip.

In practice, using a pot spray gun we bump up the MEKP to compensate when working on small parts and thinner gelcoat. Relatively means 800 gr/m2 on hulls and 450 gr/m2 on small parts.

I did not have the time to search for the printed knowledge but I am sure I have it in authority in one of my books. Should there be a need, I can research the author(s).