Thought id post about our recent success in incorporating doped graphene nano platelets into sla resin on our form 2.
We have been researching graphene for the past two years making our own, today we were able to incorporate it into black v4 resin at a ratio of 1%.
From the first tests the loading of 1% was too high, I suspect you only need about 1 gram per litre also we used black resin but we wanted to see the effect on dispersion with the hardest to cure resin (in our experience). In our test we used 100ml and a 1ml of additional photoinitiator. Should also note that we had to cure with open mode set on castable as our machine has a weak laser.
Shall be trying HT soon at lower percentages. Will be interesting to see the strength and temperature performance increase.
We used ultrasound to disperse the particles. Ours is quite expensive but I’m sure a bath sonicator would also work, just take longer and heat would need to be monitored.
If anyone is interested in trying let us know, would be interesting to see others getting involved in having a go.
Cant post the videos there too large but if you wanna see let me know.
Neat! Can you tell us a little about how strong the parts are compared to vanilla resin?
We just got them off the printer so will do a like for like once we get a new batch of black resin to test the control against but there will definitely be a strength improvement we normally use our graphene in PEEK and it’s as strong as steel.
The HT resin will be better to test for strength as there is no carbon filler like the black has will post results on that next I think. It will be more night and day.
Interesting! I found HT very brittle… will be curious to see how it impacts. I wonder if one of the Tough resins might be another cool one to play with.
I agree it is, the graphene would definitely make it more resistant to breaking.
We had a markforged mark 2 carbon fiber printer it produced great parts but our thinking is if we use the HT resin as the base with the graphene we may get parts that are comparable to the markforged system, which would be really exciting.
Yea and tough your right might be a case of just incorporating into the right chemistry good idea.
Cheers, we are eventually gonna be selling it at some point but at the moment we would like to get more data if you have a bath sonicator and would like to try it on a particular resin we could send you some if you let us know the results just pm me
The Mark 2 prints with a continuous fiber strand, right? Do you have any experience how much you lose in the way of properties when you step down to their chopped fiber mixtures? (I realize pathing and how carefully the continuous-strand part was designed will factor in). I’m assuming this project is expected to fare somewhere below both of those… but can’t wait to see. Hope you beat Formlabs to a fiber-infused resin option ;-).
Also how’s the toxicity / handling considerations of the nano platelets?
Correct Markforged prints continuous carbon fiber, however the nylon they use is not a thermoset only a thermoplastic so there can be issues of delamination from our experience. There chopped fiber nylon is really just a standard nylon with 25% chopped strands it does enhance the properties of nylon but really isn’t structural. So its a big step down. But saying all that its a wonderful machine and never failed us once defiantly worth the big price tag, just a tad out of the average makers price range
In our PEEK mix we use longer strands with Graphene and the strength enhancement is far beyond what they have but it is injection moulding material.
No we hope our graphene would fair very well against an FDM as the resin once cured is set and shatters before it bends. Theres no need to use fiber in this case the graphene itself is the reinforcement.
Its only carbon one atom thick so not toxic however you really don’t want to be breathing it in, it can become airborne as its so light.
Update on strength, it was an adhoc test but I loaded 20kg on the end of a 12mm thick dog bone in the shop press and not a budge and this is black resin. It’s also not yet fully cured most likely.
I hung off it there putting my entire weight on it and I’m about 70kg and snapped after a few seconds of me pulling on it. So floating around below that weight at that thickness. But this is only the Standard black resin.
looking forward to trying HT with it.
Will post pics as soon as I can compress them.
If your tensile dogbone was ASTM Type I with a cross section of 12.7x3.2mm, then 70kgf at break would work out to an Ultimate Tensile Strength of about 17 MPa
If you have access to a tensile testing machine, it will really help with with making consistent quantitative comparisons. Also, you should be able to print your tensile dogbones vertically on the build platform to avoid any issues with early-layer flashing or flaring in the gauge length of the doggone.
Didn’t test tensile strength was flexural but thanks for the link. Yea I printed vertical. W12mm x H12mm x L100mm and had me on the end of it so a lot of leverage would be hard to quantify the exact force without a machine like you said even knowing my weight.
I’ll just run the same test without graphene to get the control.
I suspect HT will be better as it has a lower bend percentage much like epoxy systems. I assume it’s some form of epoxy acrylate.
Would be cool to send you guys some if you wanna try it for yourselfs
If you can hang off of it in a 3-point bend configuration with a known span, you could estimate the flexural strength that way!
I just did a leverage force calculation and got the distance from the fulcrum (1 inch) and the weight (me). Force exerted should come out at around 210kg. Because it was static in a press I can assume the calculation is somewhat accurate in terms of leverage force being exerted over the part. But again thanks for the suggestion shall do and post results.
In that regard it’s like Carbon FIber dust. Which definitely isn’t characterized as “non-toxic”. If breathing it is bad, it’s toxic. It’s not just about eating it.
Do you have a MSDS for the Graphene?
Well with regards chemical side reactions carbon is inherently inert is what I meant but I understand what you mean it can become airborne and that can be a hazard like I said. So yes would have to be classed as a D2B which would be the same class as asbestos acetone etc.
Perhaps we could disperse ourselves in the resin prior to shipping to avoid the worry. Good suggestion.
We haven’t published the msds yet, we aren’t selling any for the moment. Still testing.
I thought asbestos is D2A which I think makes stuff one notch less hazardous?
Your right I just had a look again asbestos would be in D2A and not D2B. This would be D2B.
Classified more as an irritant. Still “toxic” tho
I’m interested in seeing where this goes. Please keep us updated.