This is a question for the chemists out there. I know we have a few.
Recently looking at the Cerex web site, I noticed this page that makes an interesting claim: that Nylon 6,6 actually bonds chemically with epoxy.
I’ll try to link it here: http://www.nfusionveils.com/docs/NfusionEPOXYadvantage.pdf
This is the first time I’ve heard this, but I don’t have a great working knowlege of epoxy chemistry.
So, what do you think? Does this claim have merit?
thank you,
the other drew
Lemat is the guru on this subject…
Yeah, I’m hoping he’ll chime in. Greg Loehr, too, though he may need to refrain from making any endorsements even if it’s true.
How do you define “chemical bond?” The strongest chemical bonding is covalent or ionic. The weakest bonds are dipole-dipole interactions and hydogen bonds.
Your link is talking about “hydrogen bonding” between epoxy and 6,6 nylon.
A hydrogen bond is what causes water molecules to form a liquid. The hydrogen and oxygen atoms in water molecules are attracted to one another because of their partial positive and partial negative charges. Hydrogen bonds are not “covalent.”
“A hydrogen bond is the electromagnetic attractive interaction between polar molecules, in which hydrogen (H) is bound to a highly electronegative atom, such as nitrogen (N), oxygen (O) or fluorine (F). The name hydrogen bond is something of a misnomer, as it is not a true bond but a particularly strong dipole-dipole attraction, and should not be confused with a covalent bond.”
“A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding.[1]”
So simply put, it is a chemical bond. As opposed to a mechanical bond, where one part wraps around and covers another part, but doesn’t really bond with it.
In surfboards and simply put, nylon 6,6 gets glued really well by epoxy, and lasts a long time, even through impact.
Fiberglass only bonds because it has a coating on it. It seperates from the resin kind of easily. Look at all the little fractures around a pressure ding.
Polypropeline is awful. Epoxy peels right off it. It does work as a release sheet, and that is exactly what you don’t want in your surfboard.
So why do some brands add polypropylene to their laminations? Because it is super cheap, and looks kind of cool.
Water moleucles do not adhere significantly to anything with their hydrogen bonds. The the oxygen and hydrogen atoms within the water molecule itself are held together tightly with covalent bonds between the atoms.
I suspect the most important aspect of epoxy bonding with fiberglass cloth or 6,6 nylon is the “mechanical bond” created when the epoxy surrounds the fibers and hardens. This is why good saturation is important.
Saturation will be influenced by hydrogen/dipole bonds.
I’m no science dude… But my experiences are similar to what everysurfer is saying.
When I started playing with nylon I first did some test samples on sheets of eps…
One of the tests I did was doing all types of skins hand laminated onto the eps… Once dry I would try to rip the skin off the EPS.
Results -
fiberglass would rip off quite easy with min beads stuck to the fiberglass…
Nylon (all nylon not just 66) would rip off with a layer of EPS attached…
Don’t know why… But I think that means that it stuck better to the foam… Just my 2 cents…
Stoneburner, a question for you. With a smooth sheet of nylon 66 and no texture for mechanical bond, is there a significant bond? How much force is required to separate the two? At least my real world testing says the two bond quite strongly. At least strong enough for a surfboard.
Are you saying 6,6 nylon has no porosity?
Does 6,6 nylon saturate with resin?
Hydrogen bonds are weak in the grand scheme of things. You could compare bond dissociation energies to H bond energies, although I’m not sure one for H bonding in this instance is available.
Also, don’t underestimate weak interactions. I’ve got no idea if this one is significant, and now I’m rather interested and will look. But kevlar, for example, has a ton of h bonding going on too, which supposedly helps it achieve it’s properties. Don’t forget you’re working with atoms. So one h bond at a low strength times 10^23 or some huge number of atoms can have an effect.
I think I heard that the short range attractive forces, like vdw forces or induced dipole interactions or whatever, aid in holding eps together.
Also is anybody on here a practicing chemist? I just graduated with a bs in chem so I’m super stoked a chemistry thread came up.
I agree with stoneburner though. The mechanical bond is probably the big player. If the resin is attracted to the fabric by h bonds, then ease of sautration might be enhanced.
Again in my experience
Nylon saturates but I don’t know why this would be better bond than fiberglass… Does anyone know the different saturation points of each fabric?
Take a piece of extruded nylon 6,6. Granger sells it. No porosity, no saturation. Do the same with sheet glass, and sheet polypropylene. Cure some epoxy on it. Peel it off all three samples. There’s your answer.
In the real world of surfboards, cordura nylon is like nothing else. Not even close. Then add a little twaron and microbaloons slurry. More to come soon…
Are you saying that Cerex nylon is superior because of the hydrogen bonds (chemical bonding) as described in the OP’s link?
I would never say such a thing…
I would have to ask a chemest about that. What say you stoneburner? Is nylon 6,6 in a woven fabric superior to spun glass woven into fabric?
Oh, by the way, cerex nylon non woven is a good bonding layer/ sealant layer between foam and skin, Cordura nylon 6,6 is for laminating.
I do not know whether Nylon 6,6 is superior to fiberglass for building boards. I have never used it.
I have been discussing the OP’s question about the information found at the link he posted. This is what stands out most to me:
http://www.nfusionveils.com/docs/NfusionEPOXYadvantage.pdf
“Hydrogen bonding …Nylon 6,6 which ‘improves wetting efficiency’ and gives a resin-rich surface,” addressing thermosetting resins.
Do the Nylon 6,6 products you use for building surfboards saturate with epoxy resin. That is, after wetting out, does the resin penetrate from one surface of the fabric to the other when you laminate it to the board?
I use different nylon 6,6 products. Cerex n fusion wets out pretty easy. 160 denier cordura wets out with a little effort. 330 denier cordura saturates with great effort and a little xylene to thin it. But they all wet out.
I am not a chemist but and mechanical engineer, and what i know is that nylon as all other thermoplastic is a shit to glue. If you take a smoth surface of nylon, nothing will glue on it, that’s make an excellent realased vaccum bag (http://www.acpsales.com/Nylon-Vacuum-Bag-Tubes.html).
Bond of resin and fiber always a problem in composits tech. Every material designer claimed that their product have good bond. Every part designer need to test it (protocole of building, final resistance) to be sure (it’s wrong again LOL). As for kevlar, diolen, xynol, dyneema, spectra, innegra, etc chemical adhesion is really poor and negligeable relative to mechanical bond. Glass “chemical” bond is slightly better because of sizing.
Hand peel test of nylon lam with current surfboards epoxy on eps, like other stretchy fiber, seem superior because those fiber have a high elongation to break and low stiffness modulus, so when you peel the skin it deform and break while you tear out eps bed. Do same test but peel the skin with a dynamometer, what you see is you need more forces to tear out glass skin but glass skin stay in one part so you think it delam. Look under the skin you sea eps bead glued, eps tear out. Peel test resistance is a foam problem. If you want to increase noticeably energy to peel resistance increase shear resistance of foam (this is the main principle of hydroflex root fiber). Or use a stiffer skin that take more load before tear foam bed (that’s “sandwich skin” principle).
Never forget: resin must have and higher elongation to break than reinforce. Reinforcing fiber only reinforce in tensil toward fiber lenght, resin take all other loads.
Sorry for my frenglish.
Almost perfect lemat. The fibers tensile strength is one area where the fiber is more important than the glue. Glass as a material is brittle. Spun in a fiber or in a window pane, it fractures on impact. Once the glass fractures, you only have the glue’s strength. Nylon, mixed with twaron has higher tensile strength than glass. Nylon isn’t brittle on impact, so it doesn’t fail on shock. There is much more to a fiber than just tension and compression.
If a fiber has zero elongation to break, but it has such strong tensile strength that it never stretches, it will work fine. Twaron is an example of a fiber that doesn’t stretch, but works really good in a laminate.
Ok I have a question… For lemat and everysurfer… Kevlar and glass woven into a matting has anyone used this? I know it’s expensive… But would that be the best of both worlds? Impact strength and stiffness of fiberglass?
The nylon I’m using… doesn’t fell like it stretches? And the board I’m almost finished … doesn’t feel like it’s any flexier than a normal E glass board but a hell of a lot stronger? But until I ride it … I won’t know… But my feeling is that I’ve found the best alternative to fiberglass so far… But cheaper!?