Carbon, resins, and sunlight.

[William]

I'm currently reading "Oceanography and Seamanship" by William Van Dorn and I came across a passage on construction and the use of composite materials and am curious if and how this might apply to CF frames, wheels, and parts construction. Obviously they utilize resins as well.

" It's not commonly realized that resins almost never cure absolutely, but continue gradually to stiffen and embrittle over the years. The process is accelerated by sunlight (ultraviolet rays), and thus decks and cabin roofs are first affected by the appearance of crazing, or small cracks, at inside corners or at other points of stress concentration."



William

[beungood]

Big guy, are you trying to tell me something....... :no:

[Kevan]

I can tell you that the clearcoats they use are UV preventive. It's up to the user whether they want a clearcoat applied to their CF frame, but if they choose not to, to go nude... the recommendation is that the owner periodically throughout the year (3x, I think) apply what basically is suntan lotion for CF. The product recommended by Calfee is in fact meant for marine use.

[SoCalSteve]

out in the damaging UV rays 24/7/365???

Boat surfaces are exposed to this and other damaging stuff (salt air,etc) all the time.

I would think that you'd have to leave your CF bike exposed to the elements for many years, 24/7, for this to start happening.

Just a thought (dont know if its a good one)

Steve

[William]

out in the damaging UV rays 24/7/365???

Boat surfaces are exposed to this and other damaging stuff (salt air,etc) all the time.

I would think that you'd have to leave your CF bike exposed to the elements for many years, 24/7, for this to start happening.

Just a thought (dont know if its a good one)

Steve

My thoughts weren't so much about the UV rays (accelerant), but more curious about the "resins almost never cure absolutely, but continue gradually to stiffen and embrittle over the years."


William

[Spicoli]

IMHO you will probably toast them hitting a few potholes before any of that could happen, I think?

[vaxn8r]

Not many people on this forum wear their bikes out...I would guess. I'm trying though.

[William]

I'm not inferring that carbon bits are going to crumble in a few years. But along the lines of what Van Dorn wrote: will a carbon frame still be around in 25 years like my old Super course fixie? Just wondering.



William

[SoCalSteve]

Tube amps are still around...so is vinyl.

But, CD's and MP3 players are much more prevelant.

Steve

[Kevan]

mid-late 80's CF bikes out there proving they can survive.

[bluesea]

" It's not commonly realized that resins almost never cure absolutely, but continue gradually to stiffen and embrittle over the years.
William

There is some truth to that statement, but it seems too far-reaching and somewhat misleading.

[Serotta_James]

I had a long talk with Mike Lopez yesterday. He is the chief composites engineer for Reynolds and claims that the concern about sunlight and UV rays negetively affecting carbon is completely unfounded.
I for one believe him.

[Fixed]

Tube amps are still around...so is vinyl.

But, CD's and MP3 players are much more prevelant.

Steve
bro I like this dude cheers :beer:

[bluesea]

Tube amps are still around...so is vinyl.

But, CD's and MP3 players are much more prevelant.

Steve

non sequitur (did i just say that?)

[William]

I had a long talk with Mike Lopez yesterday. He is the chief composites engineer for Reynolds and claims that the concern about sunlight and UV rays negetively affecting carbon is completely unfounded.
I for one believe him.

Again, I'm not as curious with the UV part of the statement or equation then I am with the resins used in laying up the carbon fiber. The claims that "resins almost never cure absolutely, but continue gradually to stiffen and embrittle over the years" are what interests me.
I don't beleive there was a claim here that UV adversly affects Carbon fiber. It's about the resins used.

Just like when you lay up fiber glass, you have....

Fiberglass weave & the resin you lay it up with.

Carbon fiber weaves & the resins you lay it up with.


Time to put on my science mask and dive into the murky science waters and see what I can find. :)


William

[wanderingwheel]

It is true that carbon fiber and fiberglass composites act like concrete and can take a while to finally cure. However, if the part is baked at a high temperature (300-500 F), it will cure completely before it arrives in the users hands. Nearly all composite bikes, parts and frames, are heat cured. Most boats are not because they are simply too big.

[bluesea]

It is true that carbon fiber and fiberglass composites act like concrete and can take a while to finally cure. However, if the part is baked at a high temperature (300-500 F), it will cure completely before it arrives in the users hands. Nearly all composite bikes, parts and frames, are heat cured. Most boats are not because they are simply too big.

I know this is off topic but state-of-the-art carbon/epoxy racing yachts of *all* sizes are vacuum bagged and cured in full-sized autoclaves.

[OldDog]

Big Willi - I work with composites which are a laminated product with canvas as the substrate and the resin being a phenolic. The product is cured under intense pressure and heat. The resin does continue to age however it does not become embrittled, simply changes to a darker shade over time. I have seen many of these components that have been in service 30 - 50 years with no concerns as to failure due to resin issues. I speak of this resin only. There are many, many forms of resins, for phenolics carbons, fibreglass, etc. I would have to think that carbon fibre, origianlly being engineered as an aerospace product, has a variety of resins that have been tested for application in extended life products. Chemistry, particulary plastic engineering, is an amazing science.

[bluesea]

I always assumed that with bicycles its all carbon/epoxy.

[William]

Thanks OldDog. :beer:

Is there a standard resin mix used in laying up CF, or are there different mixes used by different manufacturers?

I always assumed that with bicycles its all carbon/epoxy.

Is it resin or epoxy? I thought the epoxy was used to join the tubes, resin was used in the lay up?


William

[lnomalley]

different mixes by different manufacuterers as well as different mixes within a single manufacturer's line. Easton's bit about nano-tubes refers to the resins and not the carbon, and sometimes the deadness of some frame comes from too much resin in the mix. it's as much about the resins as it is about the carbon....







Thanks OldDog. :beer:

Is there a standard resin mix used in laying up CF, or are there different mixes used by different manufacturers?



Is it resin or epoxy? I thought the epoxy was used to join the tubes, resin was used in the lay up?


William

[bluesea]

Is it resin or epoxy? I thought the epoxy was used to join the tubes, resin was used in the lay up?


William

Basically the same thing. Epoxy is used as a glue or a resin. Glues can be mixed with fillers to enhance gap filling properties. I wonder if they use liquid epoxy or PREPREG epoxy in bicycle frames?

[nicrump]

Basically the same thing. Epoxy is used as a glue or a resin. Glues can be mixed with fillers to enhance gap filling properties. I wonder if they use liquid epoxy or PREPREG epoxy in bicycle frames?

both the tubes and joints on my frames are prepreg epoxy/carbon. cured at 250f which qualifies at "post curing" of the tubes. i do work with "wet resin EPOXY" for some repairs or specialty work.

http://crumptoncycles.com

[Kevan]

has only failed once.

Sandy, care to share with us your sad story?

[vaxn8r]

Big Will, why do you care about CF so much all of a sudden. Purchase plans? Or just concerned for our welfare? :)

[William]

Big Will, why do you care about CF so much all of a sudden. Purchase plans? Or just concerned for our welfare? :)

...I LOVE YOU GUYS!!!


That passage in "Oceanography and Seamanship" got me to thinking about the topic as it relates to cycling. Obviously he was talking about the use of composites and how it performs and relates to heavy sea events. He explains how weakened and/or poor designs and construction methods can lead to catastrophic failures in even moderate sea states.
As a parallel, he talks about racing boats and the trend toward lighter designs and materials and how they are dangerously pushing the envelope compromising design strength (= lighter weight) in the name of speed. Sound familiar? ;)


William

[bluesea]

As a parallel, he talks about racing boats and the trend toward lighter designs and materials and how they are dangerously pushing the envelope compromising design strength (= lighter weight) in the name of speed. Sound familiar? ;)


William

Yup, the French--competitive single-handed globetrotting men of iron, par excellence. Insane. There have been a number of spectacular failures, often occuring in the Southern Ocean.

[davep]

Yup, the French--competitive single-handed globetrotting men of iron, par excellence. Insane. There have been a number of spectacular failures, often occuring in the Southern Ocean.
Yes, based on competitive ocean sailboat racing, bicycles are designed quite conservatively. If bikes pushed the edge as these boats do, there would be a broken frame or fork in just about every major race.