What is difference between Epoxy & Polyester Resins

[ondarvr]

PAR

[quote]Second point is, that Epoxy curing is much better (predictable) to handle, than Poly. This makes a far superior layup in the average manufacturing process.

Not exactly, one of the big reasons polyester is chosen to be used so often is because of how easy it to use in production, the gel time, cure profile, visc and thix can be adjusted easily to conform to most any need. Gel times can be from 2 minutes to more than a day if needed depending on the formula and catalyst. The laminate can be very thin, at less than 20 mils, or many inches thick and be done all at one time. In a laminate polyesters tend to stay in place and not drain out, so they are much easier to work with in a vertical application.

There is other research and testing going on right now that may convert much of the epoxy infusion production over to VE. The reason is that as the viscosity of epoxy is reduced to the point where it can easily be infused, the physical properties are reduced to that of VE or very close (sometimes better, sometimes worse). So with the price difference (almost double for epoxy) and the ease of use, VE may more often become the resin of choice for high end applications.

[ondarvr]

apex1

The barrier coats I'm talking about are VE products being used behind the gel coat, not the epoxy products used in post coat applications, although these epoxy products do work very well.

I have read most of Pascoe's stuff, in detail, it was more than a year ago though, so if he's released new information that says he has witnessed a composite boat being built, or knows the names of the products used in the process, this will be new information. He had stated these things in an article he released titled something about not recognizing the products used in building production boats.

As far as getting sticky and working with the goo, I've been working on and/or building composite boats since I was around 12 years old, the last 15 years I've been involved in tech service to the marine industry, plus many others industries in the composite tent, so my experience is not limited. Just this week I was involved in gel coating an 85’ yacht and infusing a 40’ offshore racing hull with carbon, Kevlar and in places a foam core. I almost forgot, there was also the infused wind blades. I have 40+ years of hands on work in the composite industry.

[pamarine]

Originally Posted by Fanie

Can someone give me an indication of the difference in strengths between say 10 layers of glass, one with polyester and one with epoxy, applied same ratio and same glass. Also indicate the grade of polyester and that of epoxy.

Thank you.

I wonder why a layup's trength is determined by the glass and not wether you use polyester or epoxy.

A layup's strength is determined by the following:

Matrix used and density (Wood, E-Glass, S-Glass, Kevlar, Carbon, Aluminum honeycomb, etc)

Fiber Weave (Plain, Crowfoot, Twill, Uni-directional, bi-directional, mat, etc)

Resin Used (Epoxy, Polyester, Vinylester, etc)

Binding agent used on the Fiber (if applicable)

Resin to Matrix Ratio

With most boats only three of these variables come in to play (although all could in more engineered constructions), Resin used, Matrix Used, and Resin to Matrix Ratio.

Anyone computing the strength of the layup should want to know all of the factors, however, not just how thick the glass is.

Originally Posted by ondarvr

apex1
I have read most of Pascoe's stuff, in detail, it was more than a year ago though, so if he's released new information that says he has witnessed a composite boat being built, or knows the names of the products used in the process, this will be new information. He had stated these things in an article he released titled something about not recognizing the products used in building production boats.

Do´nt know if there are updates, except for the never ending core nonsense.

I think you misunderstood me quite a bit. I did not question your knowledge. I had a question in my last post thats all. And we are processing around 800 to 1000 tonnes of resin per annum (actually we make boats with it), both VE and EP, each where it belongs.

[quote=ondarvr;316083]PAR

Second point is, that Epoxy curing is much better (predictable) to handle, than Poly. This makes a far superior layup in the average manufacturing process.

Not exactly, one of the big reasons polyester is chosen to be used so often is because of how easy it to use in production, the gel time, cure profile, visc and thix can be adjusted easily to conform to most any need. Gel times can be from 2 minutes to more than a day if needed depending on the formula and catalyst. The laminate can be very thin, at less than 20 mils, or many inches thick and be done all at one time. In a laminate polyesters tend to stay in place and not drain out, so they are much easier to work with in a vertical application.

You adressed this wrong, it was´nt PAR, I made that statement.

And it is completely valid, though I was not talking about infusion and did not talk about special applications. What I had in mind was a amateur build.

We are not in the "Industry has a question" sector here. A novice asked for help!
And it is 200 times easier for a novice to completely fu.k up his job with poly then with EP.
Just the fact that your layup schedule in EP is easier to fix and handle makes the difference between producing a onion or a boatskin. Right?

Regards
Richard

[pamarine]

Oh, and you asked for a comparison:

Comparison of Boat Building Resins

Originally Posted by pamarine

Oh, and you asked for a comparison:

Comparison of Boat Building Resins

Thanks!
though I did´nt ask......I know.

[ondarvr]

Originally Posted by apex1

Ondarvr
you think DCPD´s are still the most used resins? I thought even my dumbest competitor would have given up on that crap!?

Yes they are, and by a large margin.

Part of the problem was created by the industry itself. There were agreements made with the regulatory agencies to reduce HAP (hazardous air pollutants) content to lower than 35%. Most resins aren't very user friendly with this level of styrene (or other products), they're thick, poor curing, difficult to roll and spray, don't saturate the fabric well and have other issues. If you blend Ortho, ISO or VE with a DCPD you gain back some the good handling aspects and can get below the 35% mark, but you also end up with a lesser product. Right now the 35% level is sort of limiting which products can used in production, although some companies can get around it, it can be costly to do so.

[pamarine]

Originally Posted by apex1

Thanks!
though I did´nt ask......I know.

that was for Fanie, you snuck a post in between

[ondarvr]

apex1

This is getting so busy its hard to keep track of who you're responding to, but is fun.

Originally Posted by ondarvr

apex1
This is getting so busy its hard to keep track of who you're responding to, but is fun.

Oh,
I´m on track, do´nt worry...
And producing in Turkey we do´nt know about regulations. That means WE set the standards, and they are worlds ahead of the average US sweat shop, like See Räi and other horse bucket manufacturers.

Coming from plain wood Epoxy building (which remains to be the biggest part by numbers), we just recently went to VE for the larger formats above 32meter. So we had to build completely new, and had the opprtunity to build the shops to proper standards.

[ondarvr]

Just so its clear, I have no argument that epoxy is a superior product to polyesters and VE in most ways. The problem is that many think epoxy is "the" only resin that can be used to build many products and they use the standard "see it failed in this application one time" argument and discount its use in most any application.

Most people here use epoxy and it is the product they should be using for what they build and their clientele, but epoxy isn't the only resin that can be used successfully in the marine industry. Most of the failures are from a poorly chosen resin based on a few cent per pound difference that isn't even recommended for marine use. Then using untrained and under paid workers with little supervision to build a poorly thought out design with incorrect methods. When it fails in some way they blame it on the junk poly-stuff that smells so bad.

As PAR has mentioned before, there was building boom that took place where everyone though polyester would work very well over a wooden hull. As many of these hulls began to fail for one reason or another, many just from poor workmanship, the line of thought swung the other way and epoxy was the only product to use in every application. As time goes on its now beginning to swing back a little in the other direction and people are re-examining the data to find that other resins will fit in and when used correctly the result can be very good.

[Fanie]

You guys can believe what you want, but here is another reason for using polyester resin.

MCRS uses polyester resin to build their aeroplanes with. This includes the Express, Tango, Kiss cruiser and the MCRS series. The reason - polyester resin is more fuel resistant than epoxy and leave less micro holes.

Also do yourself a favour. Get some spec sheets of polyester resins (you get different grades) and compare them with that of the epoxy range.

You guys seem to forget another very important factor. The glass you use is either prepared for polyester resin or for epoxy. This glass coating is what allows the binder you use to work optimal with that glass. If you use the wrong type of glass or use uncoated glass you will have a less strong layup.

There is very little, if any difference between a polyester resin layup or an epoxy layup. The important factor is the method of application.

[pamarine]

Originally Posted by Fanie

You guys can believe what you want, but here is another reason for using polyester resin.

MCRS uses polyester resin to build their aeroplanes with. This includes the Express, Tango, Kiss cruiser and the MCRS series. The reason - polyester resin is more fuel resistant than epoxy and leave less micro holes.

For any aircraft manufactured with polyester resin I can show you 10 manufacturers using Epoxy Resins. In Fact, the FAA doesn't even mention using Polyester resins on certified aircraft repairs. And I should know, I'm a certificated Airframe & Powerplant Mechanic with an Inspector Authorization.

Not only that, but it is recommended that polyester resins not be used on wood due to the risk of fire from the extremely unpredictable exothermic curing reaction. (unpredictable in the field due to the less-than precise resin to catalyst ratios used by most repair technicians.)

Also do yourself a favour. Get some spec sheets of polyester resins (you get different grades) and compare them with that of the epoxy range.

You guys seem to forget another very important factor. The glass you use is either prepared for polyester resin or for epoxy. This glass coating is what allows the binder you use to work optimal with that glass. If you use the wrong type of glass or use uncoated glass you will have a less strong layup.

There is very little, if any difference between a polyester resin layup or an epoxy layup. The important factor is the method of application.

See my post above for the variables that affect the strengths of a composite layup.

if you want to use Polyester Resin, then that is your choice and for most boat-building applications it will be adequate. But generally speaking, even though Polyester Resin may be good enough for a given lamination, epoxies will outperform them in the same use.

Originally Posted by Fanie

You guys can believe what you want, but here is another reason for using polyester resin.

Fanie

just say you love the smell................ ok?

The other "arguments" are in favour of Epoxy.
And be sure, we know the many many different treatments of glass and other fibres, on the market.
We make our business based on such knowledge.

Regards
Richard

[PAR]

I have no idea where you're getting you information, but it is direct conflict will known testing and facts Fanie. It could be that we are all wrong (even though I've been beta for these tests on occasion) or that you are grossly misinformed about the abilities of 2 dimensional resin systems (polyesters). You may be a fan of polyesters and they have a place, but your statements can't be supported with facts or testing.