:: View topic - Experiment Poly-U Glue vs Epoxy

Since skiing is over for me this season I decided to run some tests in the off season. The objectives for the tests are:

1. Compare the strength of different layups materials.

2. Determine if Polyurethane Glue (Gorilla Glue) is a suitable bonding agent.

3. Compare strength differences between epoxy and Polyurethane Glue.

Hopefully youll find this information useful.

I started the tests with poly-u glue first since I wanted to see how well it bonds. The reason I chose a cork layup is because someday Id like to start using it in a ski, perhaps a green ski to provide a dampening effect.

All materials below measure 3in wide x 36in long (76.2mm x 914.4mm). Each sample contains 2 layers of maple veneer for the core. All samples were pressed separately without heat.

I plan on conducting more tests with other materials as time goes on.

Material list to date:

FG - Triax 20 oz with 7 carbon fiber strips

Core - maple 1/16in thick (1.6mm)

Cork - .8mm (www.corkstore.com)

AL - .24mm thick (sanded using 80 grit to increase adhesion)

Epoxy - QCM EMV 0049 resin ECA 032 hardener

Polyurethane Glue - Gorilla glue (approx 14 fluid oz used in the 3 tests).

Water - I dampened all the materials before layup as suggested by the makers of Gorilla glue.

VDS

Ptex base

30lb weight (13.6 kilo)

Wixey Digital Angle gauge model WR300 to measure angle of deflection

Layup Samples:

Observations:

As expected the metal layup was extremely firm. I used VDS with the AL to provide better adhesion. It retained 5mm camber where the others had little or no camber. The FG layup was the next firmest with the cork being the softest. No surprise here.

Bonding Results:

No problems with the bonding of materials using Polyurethane glue. As expected the Fiber Glass layup required the most amount of glue in order working into the fibers.

The glue expands 4-5 times when curing. I wondered how this would affect the bonding of the materials. But all the layups bonded firmly.

Torsion testing:

I set up a simple torsion apparatus similar to the ones used in the links below: http://www.skibuilders.com/phpBB2/viewtopic.php?t=407&postdays=0&postorder=asc&start=90

http://www.doctorsnowboard.co.uk/?page_id=305

I noticed during my testing the position of the torsion apparatus in relation to the samples is important as the measurements could vary during the tests if the setup was not consistent from one test to the next.

I conducted torsion tests at a single 6in interval on each sample using a 30lb weight to twist each sample. I zeroed out the Angle meter before conducting each test and then applied the weight.

Im considering on designing a more reliable torsion apparatus. I noticed as was I testing the sample layups were also bending upward slightly. While I did not want that to occur, I couldnt prevent it so I had to be as consistent as possible with the setup and positioning of the apparatus.

Torsion Results:

Looking at the numbers above, the metal sample is twice as firm as the FG sample and nearly 4 times more firm than the Cork sample at the 6 inch mark.

Deflection testing:

Each sample layup was clamped 6inches from each end to work tables. A 30lb weight was suspended from the center of the samples. I measured the amount of deflection in millimeters at the center point.

Deflection Results:

Here's some pics:

Fiber glass layup:

Metal layup:

The pic only shows 1 layer of AL but there are 2. One is on the bottom.

Poly-U glue expands:

I was little surprised by the amount the glue expanded. Thought this might weaken the layup but all seems fine.

The sample layups:

Testing Cork:

If I didn't clamp the ends down the cork layup would have folded in half. I did all the Deflections test like this. Notice my high tech weights

Random test:

Wanted to see what epoxy, poly-u glue and wood glue look like when applied to fiber glass. Wood glue is useless. The fiber glass almost cracked when I flexed it. The Poly-u sample flexed evenly like the epoxy sample but seemed to flex easier. The epoxy gave a nice firm even flex.

Over the next 2-3 weeks I'll repeat the sample layups using epoxy and then compare against poly-u glue.

That is incredible test work SD. Thanks for the valuable info.

SD some nice work there. I have really enjoyed reading many of your posts on this forum as I have recently decided to start researching building techniques and to move forward with pressing some of my own skis. I have a few questions for you in regards to the aluminum, if you'd be so inclined.

What type of aluminum did you use for the test? Did you have any bonding issues with the aluminum? Did you have any permanent deformation of the materials from your testing?

Thanks guys. I had to do something w/ the left over material

btw- I updated the Deflection chart with correct numbers. I realized today I didn't have the full 30lbs of weight when I did the test, I was short 1 brick.

The AL I used was metal flashing, something you can get at the home center. Pretty thin stuff but it made the samples quite a bit firmer. No bonding issues yet. I haven't tried to ripped it apart yet. I'm sure with enough force I could rip it off. It does flex w/o and noticeable weakening of the bond or delamination.

I that case, I'm thinkin' that if you had a time machine, you would go back and convince yourself that cork is not a good choice?

Cork certainly does make for a soft board. But now I know how soft. Still not ruling it out just yet. Given the thickness of my samples they're basically about the thickness of a tip/tail will have on a ski. Mixed in with a real core of say 2-10-2 or 2-12-2 may work. I'm thinking of making another sample, replacing a layer of cork w/ another layer of veneer.

Trying to determine if cork works as a dampening element as well, given the right mix.

Awhile back I contacted a guy from Cork Core. I think he told me that Burton was interested in cork. Not sure if he told me that or if it was Dr. Delam. Either way, never heard back from Core Cork.

but your cork core is half the thickness .8mm vs 1.6mm?

I see some inconsistent results do to inconsistent baselines. Am I missing something?

I think a heat cure would yield dramatically different results with the epoxy.

wait and the cork has no composite?

seems as though you are testing several different things that are not comparable?

Yup the cork is .8mm and the veneer is 1.6mm and it's plain cork like a cork bulletin board. I would consider my baseline the FG layup. All the skis I've made so far except for 1 or 2 all had the basic FG layup (wood core, FG above and below, VDS, etc) with various wood core dims. I have a pretty good feel for that and now I have some basic numbers for that kind of layup.

The idea of cork came about when I made the "going old school ski" that was all wood. It has a typical wood core, then I re-enforced it with layers of wood veneer, even a wood base and used Poly-U glue. The ski was very firm. I never really got to rip on it because of the wood base, very slow.... But I'm assuming if I did I'd get some chatter on hard pack at high speed because it's all wood. So I thought cork may absorb some of that vibration, so take a layer of veneer out and add a layer of cork, making it a little softer and maybe absorb vibration.

On my GSComp 180 ski I used for racing turned out quite good but when I really jammed on it on an icy course the ski would chatter/hop a bit. Cork to the rescue? or Metal or something else? maybe just a metal plate on top (read about that in the forum somewhere, adding a 3mm metal plate on the top w/ double stick tape reduced vibration when placed 30-40cm from the tip)

Like many others I'm toying around with the idea of making skis (on the side) for sale at a very low volume (10-20 a year at most). I'd like to offer a "greener ski" using wood veneers, cork or some other materials for the environmentally conscious, maybe include hemp in the experiments, Entropy resin, Poly-u glue,.... etc. But I need some idea of what the ski will be like, if the glue will hold and how well, will it be in the ball park of a typical FG layup in terms of durability and performance.....

So comparing the cork layup to the metal layup may seem off base, but it still gives me an idea of the difference between the 2.

At this point I now know the cork layup as it stands is way too soft in every direction, even for a beginner skier. But perhaps using epoxy will make it somewhat firmer? I won't know that until I start making the same layups using epoxy. But my guess is it will still be too soft.

The metal layup would make a really hard/firm ski and I was surprised by how much firmer it was compared to the FG layup.

As for using Poly-U glue... It says it can bond to all sorts of stuff most of which can be found in skis so I figured I try it. The biggest unknown was how it would bond to FG but so far it seems pretty good. It's easy to use, readily available, cheaper because you use less (per ounce it's more expensive but you use less, I estimate 16-18 oz per ski), not as finicky to work with as epoxy and it's less hazardous (so it says).

I agree that a comparison between an epoxy layup and a heated epoxy layup would yield different results too. But I'm not using heat yet. I've been watching all the heat blanket threads so I'm taking notes on that, maybe this year I'll have a heat blanket.

Been pretty lazy lately when it comes to laying up the epoxy test pieces. Finally got around to it today/tonight. I'll give the pieces a few days to cure. Tomorrow is expected to be a warm day so I'll let them bake in the sun all day to help cure them.

I'm going to add a new test for torsional rigidity. Basically the same as the other but using a different method. I bought a torque wrench. I'm going to use the torque wrench in conjunction with my digital angle gauge and measure torque vs angle of deflection.

I'll retest the gorilla glue layups as well and re-post the results.

BTSR 3:1

The results of the epoxy tests compared to the poly-u glue test surprised my a little bit. Overall I think Poly-U glue works just about as well as epoxy. Poly-U Glue bonded to all the materials in the test just as well as epoxy. I expected the epoxy samples to be more firm/ridged. The only big difference between the samples is the epoxy test pieces retained much more camber than the Poly-U glue test pieces.

I will build a ski with FG this year using poly-u glue.

The cork performed poorly in both samples. Not sure if cork will provide the damping effects I thought it could. It definitely does not provide any re-enforcement of any kind. It was super wet noodle boingy boingy ( ie no pop, just flop).

One side note. In the FG epoxy sample, the FG was not thoroughly saturated with epoxy in the area I first measured and it gave a soft reading. I then measured the other end of the sample that was thoroughly saturated and the measurement was more in line with expectations. So lesson learned, always wet out the FG 100%.

This wasn't a problem w/ Poly-U glue since it expands in all directions when it begins to setup.

Here's the technical data:

Comparing all 3 torsion tests:

Comparing the Deflection tests:

so elan really could be using a bio based polyurethane adhesive?!

double post

triple post!

(...damn forum)

It seems possible. The glue bonds to all the materials just as well.

a ceo of capita snowboards has confirmed that elan is using a polyurethhane resin to build their boards in this interview: http://business.transworld.net/81120/uncategorized/201213-snowboard-hardgoods-preview-capita/

pretty big news.

I tumbled upon this video on youtube and find it interesting how they do layup. Perhaps someone her gets it, as I really dont get the following,

- around 1:55min in the video they show the base with edges. It seems to me as the base is not cut exactly to the shape and is extending under edges?

-at around 2:04 they put glass fiber on top but there is non shaped black layer below seen, is this perhaps VDS?

- 3:04 and forward, cutting the ski on a bandsaw. the bottom is all black. is this the base, or perhaps the VDS extending past edges?

video link: http://www.youtube.com/watch?v=Gkbr5Djtie8&feature=related

Cheers,

The base always sits under the edge tangs/fingers, all the way to the skiable (visible bit) edge.

They just missed the step of putting the vds over the edges - this is the "black layer" you are seeing - it is just sitting on top of the edges, it's generally wider than the edges and sticks out both sides.

good eye. Not sure what that is at 1:55. VDS doesn't normally go under the edge although I guess it could.

I think at 2:04 you're seeing VDS.

At 3:04 it's interesting to see the ski at the bandsaw because it looks like the base has a slight separation already from the flashing. Perhaps this goes back to what we saw at 1:55.

At 2:54 bit of editing out of sequence too. After the ski comes out of the press they show epoxy dripping out of the layup. I'd freak at this point and put the ski back in the press.

Yeah I've always wondered about that extra back that seems to be underneath the ski. I wondered if they had used the left over base material outisde the edge to support it and keep it pushed in against the actual base.

I think though it might be a masking layer to help affix the base to the mold (+/- stop epoxy from getting on the base).

Any other ideas?

It's just tape to help keep epoxy from getting under the base. Probably a super thin double stick tape. Not a bad idea.

I have always wondered what they are doing at 1:47. I cant tell what I am seeing.

At 2:19 you can see a red pad installed around the front of the binding area...first mode vibration damping? I would be interested to know what it is and if he notches the sidewall to receive it. I guess it could also be a thin phenolic sheet for binding retention...ooh, I think I like that guess better.

As falls said, I think the full black base is due to the excess base from cutting out with a draw knife being used as alignment. This would mean your cassette only needs straight sides for aligning the flash (could be the same for all skis).

1:47, is it some edge bending machine?

they have an eastman. they cut the base perfect.

I think they have vds under their edge. I have seen this in bigger euro factories.

The red part is a mystery

Do you mean they have place vds on the base before edging? In the video you can see what looks like black flash, which means the lower cassette does not have a pocket....which means the edges must be pre-attached. How would that work with the VDS in the cyano seam?

this blew my mind... look at all those pieces in a ski.

http://www.skinet.com/ski/article/anatomy-ski-base-topsheet?cmpid=enews091712&spPodID=030&spMailingID=8167828&spUserID=MzQzODM2NjkxNzYS1&spJobID=205113447&spReportId=MjA1MTEzNDQ3S0

Yea I read that too. Looking at the diagram and the mini-blurbs in the article, you'd think, "can't be that hard".... hahaha.

Stainless steel edges??? Sign me up.

You can order that from CDW... that might cost a lot though...

Wow cool! Just remember you saw it here first

From what I've read about Capita they're using it for many of the same reasons I started looking at it, ie cost, environmentally friendly, lower cost of energy consumption which I take to mean it doesn't need a heated press.

But I'm guessing there are many types poly-u resin also.

well, the tech doesn't seem to come from capita themselves, but was developed at elan snowboards, who do all of capita's production here in austria.

i've seen quite a few hints around the web that pointed to the use of polyurethane resins in their boards long before this interview. it's called envirobond, which seems to be a name they made up. they claim that it's comprised of 60% renewable agricultural materials, uses no water and leaves very little waste during its production cycle.

i guess i'll have to call my polyurethane expert guys and ask for suitable products.

I agree, I think there was some buzz before in the forum about Elan using poly-u resin.

Let us know what you find out.

Nice research project.

I am an expert in adhesion and adhesives. Gorilla glue is a great wood glue, better than standard wood glues made with Poly Vinyl Alcohols. It just isn't structural with other materials.

Polyurethane adhesives that are structural are blends of polyol and usually an isocyanate. There are a few hundred thousand ways to make epoxy, there are at least 10 million ways to make urethane.

Urethane is very tough but for the most part do not have the overall high strength bulk properties of epoxies. They especially do not have the flexural modulus that make epoxies stiff and lively.

In the past decade or so, Bayer and Huntsman have been experimenting with plural component, high flex modulus composite urethane resin systems.

They are great products, I have used Huntsman's formulations for a pultruded product that is simply impossible to destroy in the heavy duty industrial application it is used in.

I am working with Huntsman on a formula that may be useful in ski building.

Let me add my results to yours (if they turn out to be usable).

Meanwhile, I suggest that epoxy or bis A vinyl-esters (Ashland 8084) are going to give you the best results.

Aluminium needs to be pickled in phophatic acid and then primed to give good adhesion, easily done but a pain in the butt.

Cheers,

Bloefeld

It is a soy based polyol developed by Bayer I believe. Processing is not for the faint of heart.

Cheers,

Bloefeld

how come? in their videos they have dispensers for the stuff hanging from the ceiling and they do layup without masks. have a look at this video at 1:11 min you can see what i'm talking about.

http://vimeo.com/24935335

Bloefeld - Thanks for you input. It's the research that makes ski building rewarding and fun, doing the "what if". I did have the suspicion that polyurethane glue would not have the structural/flexural properties of epoxy. This is evident just by the fact that the epoxy cures to a very hard material and the poly-glue not so much. It does seem to bond to everything just fine, so far.

This research is about finding a product that's readily available, easy to use, cost effective and a little less demanding than epoxy yet still provide good results for DIY'ers. But at the end of the day has to work.

As for liveliness, I'm relying more on a full wood core than anything else to provide the liveliness.

I have a ski made and just about ready to ski on. I'll post an update on the build at the following thread, http://www.skibuilders.com/phpBB2/viewtopic.php?t=3188

by the end of the week.

I'm going to give the 8084 a look. Thanks.

I completely agree, its like a grade 9 science fair for ski nutz.

Here is a source of information on 8084.

http://www.google.ca/search?source=ig&hl=en&rlz=1G1SNNTCENCA423&q=Durakane+8084&oq=Durakane+8084&aq=f&aqi=&aql=&gs_sm=e&gs_upl=1902984l1908359l0l1909671l13l12l0l4l4l0l182l986l2.6l8l0

If you key in Durakane 8084 on Google you will find a bunch of suppliers and more technical data.

The main drawback of this product is that it contains styrene and is smelly. However if you wear a mask with an organic filter on it you will not be breathing in any of that.

That said, take a look at the physical properties you obtain and the various ways in which you can manipulate easily the pot-life, gel time, and cure cycle. This product is great, but it will shrink a small amount.

I'm looking forward to the test results. The cork will not work, but will give you a very damp ski.

Cheers,

Bloefeld

I spent the better part of an hour speaking with my main contact for polyurethane resin systems for composites.

If you don't want to read the gory details, I can give you a very short answer as to their suitability for non-production ski makers. Forgetaboutit, they won't work.

The long answer is related to a whole bunch of things.

1) Visco-elastic properties. The more glassy the resin the more issues surround handling and cure heats. For composites 400,000 plus modulus, a glassy resin is needed. This is why most epoxies work pretty well;

2) Moisture. 0.2% moisture content in the materials will cause the polyurethane to foam. By foam I mean like house insulation foam. It takes a great deal of care and heat to drive the moisture from the materials. In the case of the wood core, it is next to impossible to do;

3) Mixing. As I pointed out earlier, mixing must be done by relatively sophisticated plural component mixing systems. The polyol and ISO should be kept under a nitrogen blanket in the tanks and the tanks should have a desicant filled dryer attached to it. ISO is great at dissolving gasses, so it sucks up water vapour like crazy. So even if you to everything more or less perfectly, you can still have a pile of foam as the ISO picks up air as it is mixed at the gun head;

4) Heat. To eliminate many of these problems, the cure should be initiated with correct levels of catalyst and a bunch of heat. This however cures the resin so fast that it will not flow into the fibre. Urethanes have been used successfully in resin transfer moulding (really tricky set-up) and I have used them with great success in pultrusion.

5) Post cure heat. This is a topic for both epoxy and urethane. Unless the resin is cured to nearly its glass transition temperature (Tg) it will not properly consolidate and achieve its full properties. Usually this requires a specific ramp up of temperature over time. For example 1 degree C per minute from ambient to 180C and hold for two hours. Then cool at half the rate. This gets complicated, but the most important thing if nothing else is done is to bring the resin to a temperature close to its Tg. Even if only for a few minutes you will get better results than just picking some random number to heat to and leaving it.

These are issues that can and have been sorted out in many instances, but for things like wet lay-up or vacuum infusion the technical issues would require many thousands of dollars to resolve and much more in testing.

My recommendation is to stick to epoxy or epoxy vinyl-ester products and give urethanes a pass unless you want to go head to head with Head.

Cheers,

Bloefeld.

Yea I realized Cork was not going to work. It was damp alright. I'm still thinking of working cork into all all wood layup ski as a damping system. I made a ski with a wood core and layers of wood veneer in place of the fiber glass. It actually skis very nice. Not sure I did a write up on it... I'll have to check my journal.

As for Head, I don't think they have anything to worry about.

Bloefeld man, thanks for all the great info!

A few years ago I was looking at alternatives for end-grain balsa for a giant panel we build. We looked at cork from Portugal. It had some great properties. Damping may actually be enhanced with it.

However I think there may be some more visco-elastic materials that may be much better. We have used rubber forever and just haven't thought enough out of the box. Bad habits that guys like you think about.

I'm thinking of some polyurethane gel materials. Spectra fibre is very damp, but needs to be treated in Fluorine gas to create functional polar groups to bond. F2 is not a home use gas. It melts your bones, so no fun in the garage shop.

There are also some low hysteresis polymers that could be used, the trick may be adhesion in those cases.

Finally, polypro honeycomb core has essentially no natural harmonic. Again though it has to be treated in F2. I can probably get that done and sell it.

I can see a pile more experimentation needed here.

Cheers,

Bloefeld

Now you're getting it! Experimenting is what we do. This is probably one of the few open source sites on the web where successes and failures are documented and shared. The variables are endless.

@bloefeld: elan also states that they use less energy now because their polyurethane system cures at room temp. seems like there's something we're missing, or it's just marketing bs.

I think we have to come up with some standards like ASME only without the need for crazy expensive equipment.

One can learn a boat-load about a composite sandwich by doing a 4 point bend test. Essentially every load dynamic can be calculated by this single test.

Maybe I have to look into some better FEA software for my Alibre CAM!

Cheers,

Bloefeld

Update on the Poly-U glue experiment.... I made a pair of all wood skis the other day using Gorilla glue, no FG in the layup. The core was vertically laminated and then I used a layer of poplar veneer above and below the core. I also use a thin layer of cork on the base in between the edge tynes as a filler and to see if it would any effect as a dampening agent.

But, the reason for the update in the glue. yes it still bonded fine, HOWEVER, after pressing the ski for at least 12hrs, some of the glue still had not cured but I did not know that. The ski looked great when I took it out of the press. I left it on the work table and then came back to it a few hours later only to find the base had small bubbles every where. The bubbles were not there when I took the skis out of the press. The bases were dead flat.

I'm assuming some of the glue had not cured, then started curing on the work table, and Gorilla glue expands when it cures.

I put the skis back in the press for a few hours and it did help, most of the bubbles did press out, but a few did not. Not sure I can grind or file them down w/o going through the base. The skis will be ok for personal use but they were supposed to be raffled off for our race league.

So word of caution if you decide to try using Gorilla Glue. I'll look to see if there is a poly-u glue that doesn't expand. It bonds great for all wood layups even when using p-tex and VDS.

Gorilla glue is moisture cured and a polyurethane. Polyurethane turns to foam in the presence of moisture. Gorilla glue could care less about the amount of heat and pressure you put on it. As soon as the pressure is released any uncured material will hunt out some moisture to cure and foam some more.

Heat has nothing to do with the cure process, Gorilla clue is a single component moisture cure adhesive meant for use with wood and other materials that absorb moisture. It does not have the mechanical properties to make a composite material suitable for use in skis.

Cheers,

Tony

Yup that's what happened, the glue found places to cure and it did. I did not use heat during the pressing and from what you said it wouldn't have made a difference.

Tony, I know you are an expert in adhesives, so help me understand why poly-U glue will or should not work (outside of the problem I had ) especially in an all wood layup of a ski? I have used it in other all wood layup skis with success and a FG layup. I realize that using it in FG layup is a real stretch but, it did bond fine and it's a ski I use racing w/ very good results. Is it a matter of time before the bond starts fail and delams?

The glue says it will bond to wood, metal, plastic, etc. I know some use it to glue UHMWPE to wood cores with success.

I've used this glue when making ski cores and in more typical applications (furniture, etc). Granted the furniture just sits there, where a ski is dynamic and constantly bending and flexing.

Thanks

If you look on page 2 you will see notes with my polyurethane expert on the topic of using polyurethane for application in skis by non-volume users.

Adhesives are not the same as composite resin systems. They can be similar but do not serve the same purpose.

In the case of Gorilla Glue it does not have the bulk properties to make a composite. No matter what you do, it will not help you create a good fiberglass matrix of enough strength to be useful.

It is great for bonding your core but there is no structural adhesive of any sort for less than $300 per gallon that will bond with UHMW. Some PU adhesives are gooey enough to sort of stick to the surface but will never cure and create a true bond. The reason is that UHMW has a very low surface energy and the adhesive has to have a surface energy of at least 10 dynes less than the plastic to bond.

I am surprised that you ever got Gorilla Glue to work in a FG layup and got decent performance from it. It has way less than half the bulk properties I would even consider for use in composite construction. I expect that the fiberglass had enough moisture content for the glue to cure. It does have excellent adhesive properties so with the combination of enough moisture and the press pressure I think you got lucky and it worked.

I like urethane resin systems a great deal, but I have only used them in making pultruded products where the cure process is subject to a great deal of control and the moisture is dealt with by preheating everything in the part.

I think there may be some polyurethane/epoxy hybrid products that my be useful, but the ski epoxies that are commonly used by people on this site are in my opinion excellent and I can see no reason not to simply use them.

Cheers,

Tony

As for bonding of UHMWPE with PU glue. It is only being used to provide enough of a bond to attach the sidewall to the wood core long enough to get the core profiled and into the laminate. To achieve even this bond, it needs to be abraded and flamed to get the PU glue to stick. Once the profiled core is in the layup the PU glues does little to nothing as far as structural integrity goes. As you point out the real strength comes from the epoxy and fiberglass matrix.

If I could figure out a way to heat cure the epoxy and not have the clamps in the way I'd use my regular epoxy to do sidewalls. But at a room temp cure with my epoxy it would not be feasible to do this.

This is a very complicated topic as it refers to surface science and the necessary and sufficient conditions of all adhesion. It is at the core of adhesion science.

To my knowledge their are 3 common methods and 2 not as well known methods to allow UHMW to meet the requirements for adhesion.

Crown plastics apparently abrades and flame treating.

Honeywell uses plasma to treat Spectra as does Dyneema.

The other common method is to corona treat the plastics.

In all cases the surface energy of the plastic is lowered and polar bonding species are temporarily put onto the surface of the plastics. In each case, over a period of time this effect is lost. Don't buy too much base material and not use it.

The other two techniques are sulphination and fluoro-treatment. Both are permanent but require sophisticated process equipment and control to perform. I have samples of fluoro-treated UHMW that are nearly a decade old and are still excellent for adhesion.

The problem you face is that flame treatment is very difficult to do properly and well. Bad treatment results in very inconsistent adhesion.

If there was enough demand for sidewalls, I could arrange to have some UHMW PE fluoro-treated.

Cheers,

Tony

Flaming is not hat hard to do, but yes to do it right can be tricky, ask most any of the builders here who do it, but it can be done successfully, ask most any of the builders here who do it.

Abrade with 60 grit belt sander, flame with a propane torch using the hottest part of the flame but carefully not to scorch the material, Do it less than 30 min before layup, and redo and previously factory treated plastics as well, for the reason you state. Test with a water drop test to make sure the surface tension has been lowered.

Abrading gives you mechanical bonding by making th surfaces hairy, the flaming gives you an oxidation layer for chemical bonding.

Complex science is not always complex in practice.

The water test is a good approximation for surface energy, use distilled water for best results, but don't always assume that because a plastic passes the water test that it has low enough surface energy to bond to any and every adhesive.

Abrading only gives more surface area for the flame treatment to react with, it does nothing in this case to improve adhesion, only the carboxyl's created by the flame treatment give you anything to bond to. The slight intertwingling of the abraded surface will only give superficial adhesion.

You are correct, it can be done and done well with practice.

The bond is not great but probably good enough. In fluoro-treated UHMW PE the plastic always failed before the bond in ASTME tests for adhesion.

I feel certain that you would agree the UHMW makes much better sidewalls than ABS.

Cheers,

Tony

Good tip on the distilled water.

Good point about the increased surfaces area for the flaming, I still feel like the abrasion does improve the mechanical bonding to some extent.

A good article on gluing plastics and the resource for my statement on flaming within 30 min of layup.

http://www.epoxyworks.com/26/pdf/Gluing_plastic_Gflex.pdf

Although this article indicates an alcohol wipe before flaming improves bonding. What's your though on that?

Des sorry for the hijack.... I may repost some of this in the uhmwpe bonding thread if it seems worthy.

No worries. It's all good info.

The point of the experiment was to find another adhesive/glue/bonding agent that was relatively in-expensive, easy to get, easy to apply and bond to the materials we use in skis/boards.

The bubbling was a real disappointment. Even though I had success of sorts w/ poly-u glue, I think it's over.

Vinman, G-flex is expensive. An alternative approach is to flame treat the plastic - 6 inch width and lay it up over a similar sized thin piece of wood, say 5 mm think. Put in the oven at the usual heat and pressure, remove, cut and bond wood to wood. I'm not the author of this method, but I can say it works.

I'm not using gflex, I just thought it was a useful article about bonding UHMWPE, specifically the flaming method they describe.

That is an interesting idea, bond the Ptex to the wood prior to ripping it into sidewall strips.....hmmm might have to think about that.

Upon reflection I think that abrading the plastic and then flaming will just give you little chunks of carbon that will break off from the plastic and decrease adhesion. So the alcohol wipe makes sense and clearly gives better bonding.

I am fortunate in that I can get a couple of strips of UHMW treated with fluorine at anytime at no cost, so I get 6,000 or so psi of shear adhesion (the failure of the UHMW)

There is a great book out there called "Adhesion and Adhesives Technology, An Introduction 2nd Edition" by Alphonsus Pocius, published by Hanser. Al gives a great description of all of the mechanics of bonding and gives a good explanation of all of this stuff. No doubt there are library copies all over the place. It is worth the read to give a good grounding in adhesion science.

Cheers,

Tony

I was going to ask about using G-flex on gluing sidewall and edges.

Looks like good product for the job. Why not use it?

As far price. It a little bit more money compared to gorilla glue but definitely cheaper per Oz compare to loctite superglue

http://books.google.com/books?id=RqCWC0j1hqQC&pg=PP1&lpg=PP1&dq=%22Adhesion+and+Adhesives+Technology,+An+Introduction+2nd+Edition%22+by+Alphonsus+Pocius&source=bl&ots=JjiCxtJtGG&sig=WVv4NxOl7vhm93_UgQ_zDZOvjzk&hl=en&sa=X&ei=SetUT4LpKMLfiAKa2cy0Bg&ved=0CC0Q6AEwAA#v=onepage&q=%22Adhesion%20and%20Adhesives%20Technology%2C%20An%20Introduction%202nd%20Edition%22%20by%20Alphonsus%20Pocius&f=false

Smooth UHMWPE would not hold well IMHO. the abrading is necessary. The a

Alcohol wipe may help. Might have to test this for myself before using it tHough. The current consensus around here is no solvents on the plastic due to the possibility of residue creating a poor bond and delam. I have a buddy in the industry I'll ask him what they do.

Nice MM. I did not know this about corse grit abrading. Thanks. I'll keep it to 80 grit from now on. This info should be in the bonding thread...

so i could just buy regular untreated uhmwpe, wipe it down with alcohol and flame treat it and it would bond better than the abraded stuff we get from isosport/crown/etc ? (given the wiping and flame treating is done properly)

YMMV. But I dont think so.

Every shop I have been to that laminates plastics has some level of abrasion and not smooth.

MR - I haven't used it. I made enquiries a while back, but then I was told about the press method. Given that I am using ski epoxy, I am assuming they designed it with these challenges in mind.

Given how critical the bondline between the core and sidewall to the failure of the planer process, I would jump on Tony's offer.

Grit levels for base material I have seen quote 120 grit. One problem is that grading is inconsistent within the paper industry. There is a research paper out there where they show a huge divergence according to brand - as seen under a scanning microscope. I think Norton came up well (from memory), whatever, it is probably worth saying that if you find a brand (AL oxide) and it works, stay with it.

ha, it just dawned on me why the poly-u failed on the last ski. My BTSR was zero!

Ha! Easily rectified!

Resurrecting this thread. After a long hiatus from experimenting I have

another experiment I hope to be performing this week. Waiting for some

9.4oz Uni Carbon Fiber to arrive. I'll create a similar layup using CF this time.

I may also make a layup of FG and CF and test them like I did for the other

test samples.

I will not be using poly-u glue this time around. I had some good results

using poly-u glue and raced on the poly-u ski all last winter. But I also had a

problem on another ski where the poly-u glue did not cure 100% before I

took it out of the press. The ski was dead flat out of the press, but then the

uncured poly-u glue started to expand under the base and tiny bumps

formed. I was seriously bummed out. Anyway I haven't totally shelved the

use of poly-u just yet.

The new Capita Snowboards homepage also says that it's a polyurethane resin they're using to build their boards at the Elan factory. I'd love to know who makes that stuff and how it performs.