What is difference between Epoxy & Polyester Resins

PAR

 

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.

 

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.

 

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.:idea:

 

Oh, and you asked for a comparison:

Comparison of Boat Building Resins

 

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

 

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.

 

that was for Fanie, you snuck a post in between

 

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.

 

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.

 

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.

 

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.)

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.

 

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

 

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.