Polyester VS Epoxy Resin comparison test - carbon / glass. Expedition lifeboat conversion.Ep102 [4K]

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EPISODE 102
I need to do a lot of composite lamination work for an upcoming project building leeboard fins for Alan the lifeboat. So, here I'm testing whether the cheaper polyester resin is a viable choice when using advanced carbon fiber / fibre fabrics, or whether sticking with standard GRP or a carbon / epoxy mix is better.
Materials from: www.easycomposites.co.uk/ and www.ecfibreglasssupplies.co.uk/
Feel free to ask any questions in the comments!
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[@davidbroman8391]

I am a Certified Prosthetist. When making prostheses that must be strong and light we use epoxy resins. The issue with using polyester and carbon fiber is that the resin does not bond very well to the fiber. Resins have a hard time bonding well to carbon fibers that’s why it snaps. They have developed surface treatments and sizings that are only compatible with epoxies . The weakest link is the polyester resin. Polyester is also a great health hazard so ventilation and safety precautions should be considered. Carbon fiber can be used with polyester, but must be suitable for the composite properties. For carbon/poly composites, the best applications are those that are lightly loaded (maybe just stiffness critical) and/or in pure tension (compressive and shear properties will be compromised using polyester). The lay up is also a factor. If you have carbon fiber separated by layered of fiberglass or matting, the lay up is much stronger.

[@PeterPan-fu2zj]

Helpful for my bow thruster installation later this winter. Thanks!

[@AlexHibbertOriginals]

Just remember that epoxy has better mechanical bond performance to cured GRP than most polyesters.

[@PeterPan-fu2zj]

@@AlexHibbertOriginals I am aware of this, thank you!

[@MCallsen]

Vanguard rings a bell (nudge nudge - wink wink) - great storage :)

[@davecoz4227]

Say no mooore!

[@AlexHibbertOriginals]

There was me thinking I slid Vanguard in there without anyone noticing.

[@lv_woodturner3899]

Very interesting. I am not likely to need this knowledge, but it is still interesting. I use resin to fill cracks, gaps and voids in my wood turning projects so just the resin. Not a relevant use case for your needs. For my wood turning needs, I am not fond of the polyester resin which is e.g., 1 drop of MEK hardener to x oz of resin. I often need small amounts of resin, much less than an ounce so it can be a challenge to get a smaller drop. Too much or too little MEK can mean the resin does not cure. The epoxy I use is a weight based mix ratio, so easier to mix small amounts of each component based on a digital scale with appropriate resolution. I look forward to seeing how you will be using the interesting tape in the future.

[@KnightsWithoutATable]

The polyester was not bonding to the fibers as well. This was what I expected when you told us the known properties of the resins. The lower bonding to the fibers can be seen in the polyester as it is bent as the fibers separate and cracking can be heard and seen in the material. The exact forces needed to break each is the real question. Mechanical fatigue and the type of fatigue is likely different between these two composites. You are not going to find reliable data on it though, even if you look it up, as that topic is currently in the academic research realm since composites and their uses are still fairly new technology while the variables can be very dramatic, just as this experiment has shown.

[@strider2175]

Interesting to see the differences in brittle fracture vs ductile failure between the different test pieces.

[@Factory051]

I've become a materials geek. Thank you mummy.

[@gafrers]

Interesting and in line with some papers i read

[@MrButtonpresser]

Underground at Westminster. Did you see and barrels of gun powder laying about?

[@Whitburn.Surfboards]

Insightful video. The other thing to consider is that polyester resin becomes more brittle over time compared to epoxy, or so I've heard. I also prefer using it as it's not kicking out the same fumes as polyester

[@skaraborgcraft]

The important part is bonding to the existing laminate. I have used polyester in conjunction with G4 as a primer with no failures with a glass overlay. Its unlikely your hull/deck joint is ever going to bend 180 degrees, so your simple test would imply that polyester is good enough. I would not lose any sleep.

[@AlexHibbertOriginals]

This wasn't an adhesion test, which is a rather different question. This test was for a standalone part. Interesting on the primer though, vs using epoxy direct.

[@skaraborgcraft]

@@AlexHibbertOriginals Last video i saw was you considering laminating the inside/outside of your hull joint, ergo i jumped to a conclusion. Without knowing the purpose of what you may be constructing, hard to say which resin would be more appropriate. At least you do your homework before investing time and money.......some dont.

[@AlexHibbertOriginals]

Yep the fender strip join repair will be a simple glassfibre and epoxy job.

[@Zigge]

You should try out a laminate with polyester and S-glass fiber. It will perfrom as high grade carbon and the weight peanealty is minimal for hand layups.

[@tikunshana784]

I think the stronger glass variety is called S2.

[@AlexHibbertOriginals]

I actually had an e vs s glass test planned, but it got buried with other videos....

[@thelatemickb6927]

ECF best serice..Feck epoxy/ Poly for me all year round. Nice garage. very clinical.

[@colinbolton5415]

How long did you leave the resins to cure before testing? I'm not an expert in composites, but I have spent 40+ years working with aerospace paints & coatings (mainly epoxy & polyurethane). We would not perform mechanical tests until the film had cured at room temperature for 7 days. Partially cured films are likely to exhibit greater flexibility.

[@davidrumbelow]

Most interesting

[@AlexHibbertOriginals]

A stretch, but thank you

[@glennrainey1227]

Did you state what the build objective is? If repair of a polyester layup then epoxy is preferred material. Is there a good reason to even think of using carbon in Alan? Dont forget electrolytic corrosion issues if metal amd saltwater in the application. The cloth manufacturer should specify approp resins Gloves, at the very least, highly advised with these resins esp epoxy as high allergenic potential and permanent health consequences. Peel ply is critical, not just to control sharp fibres but to help optimise resin ratio, to optimise bonding surface of the cured composite, and to deal with the amine blush problem with epoxies, something which hinders surface finishing incl paint adherence. Epoxy composite will only achieve optimum strength with post cure at higher temp as specified, certainly room temp cure is inadequate. post cure for a day or so inside a car on hot summers day works well, for small layups. Dont use / keep silicone materials in the same postal code as your composite layup work, or risk serious loss of bonding performance.

[@S7ARK_]

Here are a couple of suggestions: It might be beneficial to maintain a specific room temperature and humidity level during the laying up and curing process according to the epoxy data sheet. This will have a positive impact on the final results. Epoxy, for example, is known to be sensitive to curing conditions, so ensuring proper post-curing by applying heat for several hours or natural curing over several months can make a significant difference. The waxy texture you've encountered could potentially be attributed to high humidity levels. All these values will be in the resin data sheets. When performing hand layups, consider using peelply. This can be particularly helpful in creating a strong bonding surface for later stages, especially after a thorough 150-grit sanding when you remove the peelply. It also helps with proper resin saturation. Additionally, you might want to consider suspending the test articles like a suspension bridge during testing. This involves having both ends off the ground and then applying pressure in the middle. This method can potentially lead to more consistent results, as you can apply pressure using a scale or pre-weighted weights. Manual testing by hand introduces to much variability in the final results. Good luck!

[@AlexHibbertOriginals]

I referenced a lot of this in the video. Some resins require post-cure, or can benefit from it, and others don't. I kept the conditions constant for this test. The waxy surface is normal for parts that have cured exposed to air, hence the need for PE pags, peelply, or silicone paper. Peel ply would still have needed the silicone paper here as it's permeable, and would just have soaked up a little excess resin and left a rough surface for later bonding. If I were measuring deflection or exact failure values, I'd have hired a 'suspension bridge' press as you say, but this was an observational test.

[@noahgossett6134]

Just for everyone out there to not forget the 2 types of strength. Rigid amd flexible.

[@nraynaud]

without whatching all the video, I'm with you on the tiredness of carbon fiber snobs, for example carbon fibers have a very low coefficient of thermal expansion, so it make sense to embed them in very ugly and pedestrian polymer concrete for some applications.

[@kevingardner1658]

Alex I would love to be angry with you because I love working with Epoxy - unfortunately I can't as I appreciate the amount of research and work you do -So - keep calm and keep epoxying (is that a word?) cheers mate.

[@goiterlanternbase]

I found it interesting how much flex the single layer had. I would like to see, how two single layer with a foam in between compare to a double layer, when it comes to blunt impacts, like with a 400g mallet.

[@AlexHibbertOriginals]

Yes, unidirectional carbon is incredibly flexible when thin. For sure, a sandwich would stiffen it dramatically, but not help much in a point impact.

[@jmwintenn]

all the fiberglass yacht builders use vinylester, not poly. poly will absorb water at some point. i'd just use s-glass instead of carbon stuff. the lifeboat is fiberglass so s/e-glass will bond with it no problem.

[@AlexHibbertOriginals]

Oddly, via my suppliers vinylester is only a little cheaper than epoxy. Perhaps in commercial quantities it's cheaper.

[@garyphillips7993]

Would extreme temperatures have any effect on their snapping properties? I’m thinking of the cold & the way it makes things more brittle?

[@AlexHibbertOriginals]

Cold has very little effect. @easycompositestv tested this in their lab. I've never found the cold to damage my Arctic sledges.

[@minisculesix4786]

I wonder if it would do anything different when saturated with water

[@teeanahera8949]

Could it get saturated with water, I would have thought the lot to be impermeable?

[@poepflater]

I've heard epoxy keeps getting stronger... ould be nice if you can keep samples to test after a year... I wonder if the way one tends to need more epoxy than polyester to cover the same footprint has something to do with the differences..

[@mongoliansheepfarmer1097]

The carbon bike industry uses fiberglass and carbon together in key areas of the bike frame that require machining down to tight tolerances, to save cost as well as its hard to machine carbon on its own

[@AlexHibbertOriginals]

Yes, it's often also used to make cheaper fishing rods, poles etc. I suppose it would also buy a little leeway in terms of reducing brittle failures too. Top bikes are weaving in some Innegra now, again to limit the risk of a straight up snapping incident.

[@teeanahera8949]

@@AlexHibbertOriginalsyour comments remind me of a couple of the carbon fibre foiling yachts in the round the world race, massive cracks developing along huge structural areas under the constant pounding of the hull on the waves. I imagine there were flexing forces from various directions. Alan has yet to sprout foils for those 40 knot down hill runs with the Bukh champing at the bit in big waves so you should be just fine. 😅

[@TimoNoko]

Carbon and polyester do not mix too well. I had weird technique -- I worked a ball of carbon-epoxy in my hand like clay until it was thoroughly wet and used it to strengthen parts when needed. I have huge roll of single strand which becomes like wet paper when masticated long enough.

[@pete.b4197]

Put epoxi in fiber and then vacum!! That is many times stronger what you makes! Sorry i'm nosey!☺️✌️

[@zolar7a]

In keeping with the spirit of the channel you should have chilled the samples to -40 prior to testing.

[@AlexHibbertOriginals]

The heroes at @easycompositestv actually already did that when we collaborated. Performance v v similar at low temps.

[@klaasbloem]

Epoxy bonds far better to the underground, does not shrink, is stronger and can be applied without respirator.

[@Agnemons]

So, which is better? Well, as usual, it depends.

[@AlexHibbertOriginals]

Epoxy is better without doubt. It's just 3x the price.

[@LorenTedford]

Here is a thought.. I am only saying this from watching years of carbon fiber youtube videos on manufacturing process.. Try this process again but this time put your carbon fiber pieces once wet in Epoxy inside a Vacuum Chamber let it set over night then repeat the test you will see that you will gain even more strength.. It has some thing to do with Air and epoxy and bonding to the carbon fibers all some thing that is above my understanding and knowledge.

[@LorenTedford]

Some vehicle manufactures actually layer the carbon fiber tubs and then let them set inside the vacuum chamber for 72 hrs before relaying more carbon fiber and epoxy also it seems everyone has there own recipe when it comes to how much hardener as well..

[@AlexHibbertOriginals]

Professional carbon layups with prepreg are certainly a different category. They consider a 1% increase in tensile strength to be worth the added investment. I'm not sure about the air being the deal. Generally epoxy curing with air means a tacky surface.

[@LorenTedford]

Yeah its like vudu magic or some thing.. I will continue watching but A channel to check out is Mike Patey I watched him build a few planes now in carbon fiber you can kinda see how he did his stuff but I still can't find the name of the channel that had the giant tomb vacuum chamber for curing carbon fiber vehicle tubs. Its all interesting stuff just wish I understood what is happening on the chemical bonding level.. @@AlexHibbertOriginals

[@LorenTedford]

I was always curious what if you created your boat out of fiberglass then wrapped it in carbon fiber for penetration strength. Idk just talking here..

[@AlexHibbertOriginals]

That wouldn't be a goer as carbon is poor for point impact. Plus, you'd need to work out how a mechanically bonded carbon skin would behave. My guess is over a GRP shell - poorly.

[@AndyMcCavish]

The biggest revelation is that you have a label machine and you haven't gone mad with the power and labeled everything on Alan, or does he not like that sort of thing?

[@AlexHibbertOriginals]

Imagine if I did that, returned to Alan one day and found he'd swapped round all his labels.

[@crissb852]

just an FYI, polyester and vinylester resins don't bond very well to epoxy. Epoxy resins will bond to poly or vinyl.

[@AlexHibbertOriginals]

This wasn't an adhesion test, which is a rather different question. This test was for a standalone part.

[@ptonpc]

A case of, there is no 'one size fits all'.

[@SpockCycles]

Epoxy for Carbon, Polyester Resin For Fibreglass. 👍

[@chadstinson9886]

Watching and suddenly I went colorblind.

[@AlexHibbertOriginals]

Trust me, the alternative was worse.

[@gentrynewsom2080]

Laminate two plys of each clothe & resin system in a hydraulic press then test them..wet layup is outdated and weak

[@davecoz4227]

A completely uninformed idea - vacum bag. There's a channel called The Duracell Project and the lad there vacum bags all the laminates he does, be ot fibre glassing the boat or construction of carbon fibre chain plates for the sales. I dont know why but I assume it gets the epoxy or glue into all the spaces a heavy weight on a drying piece fails to reach

[@AlexHibbertOriginals]

Vacuum bagging, whether after wet lay or with infusion is good, sure. But it's not going to affect the comparison shown here.

[@glennrainey1227]

vac bagging makes excess resin leave the layup before cure, bleeding into a sacrificial matting material, so the cloth to resin ratio can be optimised. This is needed for optimum light weight components which is applicable in aerospace, or F1 car. You can get close with good technique and using peelply to soak up excess resin. Vac bag also helps to achieve layup conformity with mold, and to prevent gravity pulling everything off a vertical or overhead layup, which is really annoying.

[@AlexHibbertOriginals]

I'm not sure how this relates to my reply. No-one claimed otherwise.

[@_r_ma_]

Lots of good points, but...your test is really just comparing resins, not the resin's effect on fiber choice. With a hand layup wet out, the fiber:resin ratio is extremely low, especially without peel ply. Likely ~20-25%. So you really aren't testing the fiber properties when the matrix is primarily made up of the resins. Your test shows exactly what we'd expect of just laying poly or epoxy resins on a flat surface without any fiber. There's no reason that poly can't create a carbon fiber composite, the question is more, why bother? The only reson to use CF (and pay $$$) is because you need the extreme material properties that it can provide. But to achieve these properties, at a minimum, the part must be vacuum bagged, or better yet, infused. Otherwise, the resin ratio is too high and the matrix wont reflect the ideal properties. Going through all the extra expense and effort of these techniques seems silly if you're using a relatively flexible resin like polyester. If your part is designed to flex, why consider CF in the first place? FG will flex plenty without the brittleness and cost an order of magnitude less. TLDR: dont use carbon unless you absolutely need it and are willing to do it properly! --> $$$

[@AlexHibbertOriginals]

Likewise, you make some good points, but: 1. 20-25% is very pessimistic. I mixed up a set amount of resin, taking into account brush wastage, and there was still some resin overspill. So the laminate was not 75% resin. It was near 50:50. I agree that some infusions/prepregs give you >50% fabric, which is great. 2. Carbon is often used in applications when they need to flex. Case in point, these unidirectonal-dominant laminates can bend back on themselves before they start to snap. Thick carbon laminates are indeed stiff compared to glass, aramids and so on, but not in thinner layups or across wide spans.

[@Ian-the-real-person]

🙃 first