Epoxy or Vinyl Ester resin for this project?

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#1

So I just visited Michigan Fiberglass works (Chris is an awesome and very knowledgeable guy!) - picked up a ton of supplies (GREAT prices BTW! ;)) Couple cool projects they have going on there - both infusion. One is a kiteboard, the other a 9’ boat. Tomorrow or Thursday he will be infusing the kiteboard, then in a week or two the boat. Going to attend both sessions for sure as I have never infused nor seen it done.

In any event, Chris was very insistent on using Vinyl Ester resin instead of Epoxy for my jetski hull build (remember, this is a watercraft and will get a lot of abuse). He stated that the physical properties of it are much stronger then that of epoxy which can brittle over time.

And also instead of using an Epoxy paste/mixture as an adhesive for motor mounts, hull inserts, etc., use a product like Plexus.

Just wondering what others opinions are on this? Until now I had it in my head epoxy was the ONLY way to go.

If layup method matters, right now he has me talked into doing infusion (I am going to take my molds and materials down there when it is time) and he is going to help me out.

-Andrew

#2

Think in terms of repetitive impact. Thats what youre building your hull to withstand. You need some flex, and shear strength.

Every boat yard Ive been to has problem hulls, all in the 20 to 30 year old range. Dont recall seeing many epoxy hulls in the yard for water damage.

#3

TBH i use epoxy for all my projects altho to save the epoxy for the better stuff i am thinking about VER

I dont want my parts to crack or shatter… epoxy gives me this solution as long as the part isnt at extreme.

#4

cost is NOT an issue - i will throw that out there.

i also don’t want my parts to crack of shatter - i still have using epoxy as the solution in my brand, as i know that is what most of the major guys are using also.

just hard to fight with someone more knowledgeable then myself on the epoxy vs. vinyl ester debate…

#5

Malibu boats use VE and I don’t think cost is an issue for them. :stuck_out_tongue:

#6

Cost is an issue for every boatbuilder, even the really high end stuff. Also Malibu.

For dynamic loading epoxy is great. About all windmill blades are epoxy. (except Vestas blades). These are also epoxy glued.

As for brittleness of epoxy resins. I guess this guy has had an experience where his epoxy has been extremely loaded while still in a B-stage cure. Indeed then epoxy can be brittle. This situation specifically occurs in warm-curing resins, which do cure at RT, but need a postcure for optimum properties. (therefore all windmill blade tooling is heated)

In general epoxy has a larger elongation.

Why do yards use vinylester:
-lower viscosity and quicker laminating
-ability to use gelcoats
-cost

As for glue joints:
Methacrylates in general are more flexible than epoxies. (although the rubber toughened epoxy glues are reaching similar properties)
Plexus MA300 and MA310 are the stiffest MA glues by Plexus. The 420 series (including 900 and 1000 series for low shrinkage and low odour) are more flexible. This gives them excellent peel strength.

The flexibility also helps in vibration dampening, making the structure less noisy. And MA glues are FAST! (ranging from 50 seconds cure to 90 minutes at max.)

Price can be an issue, though…

#7

I use plexus ma310 a lot for joining and find it an excellent allrounder. The only problem that i have had with it is that it melts blue foam away that i use for pattern making and as a core for certain wings.

I also like 3M dp490 but it is much more expensive than the plexus. Takes longer to cure, but gives a stronger bond

#8

thanks for the feedback everyone…

still more confused then ever. maybe not confused but questioning which route to go.

see myself still going the epoxy route as that is what all the big name guys are using.

i have a fair amount of time before the actual layup of the parts begin - need to finish the molds.

#9

From what I can see epoxy should be more impact resistant also, at least in a theoretical sense. The term resilience comes to mind, which is used to describe the amount of energy a material can absorb before deforming. From what I have been seeing, dynamic loading conditions are difficult to model theoretically, but this resilience value can at least be used as a tool to compare one material to another. This value is a function of yield stress and strain (or elongation over initial length) at yield and has units of energy absorbed per unit volume. At any rate, from my quick searching epoxy generally has a higher yield strength than vinyl ester and as herman stated it also has a higher elongation. Therefore, epoxy should have a higher energy absorption than vinyl ester for the same volume of resin.

As always, theoretical models have limits and very often ignore things assumed to be negligible or small enough to not matter (i.e. like for this case operating temperature, strain rate, water absorption, and things like that which can and will effect values for making these calculations).

#10

Have you considered getting a sample of the VE and Epoxy you’d be choosing from? Then just making a test piece out of each and see what works better for you. I don’t know as much as these guys, but I do know there are companies that make excellent parts using VE and even PE. Experiment :).

#11

thats the beauty of having my own molds - i’m not limited to one part.

my first part i am leaning towards a wet layup / vacuum bag with epoxy.

second part vacuum infusion with vinyl ester per Chris @ Fiberglass works supervision and recommendation.

#12

Just put extra big flanges on there so you can easily use the mold with both methods

#13

for sure - 6" minimum.

that is what i did on my last hull plug.