New Filaments - Heavy Weight, Rubbery, Conductive, Semi-conductive

This is very interesting, im sure a lot of people are interested in testing your products and I'm one of them!

If by chance you still need ppl to beta test and help iron out the kinks I'm in.

Because he/she/it is a spam account?

Hurr durr. Thanks. My bad.

Guys,

I am a chemist with experience in development and testing of polymer thick film "inks" (pastes) for electronics applications. Also, development work (resulting in a patent) on making oxidized metal poweders highly concuctive for use as conductive fillers in various thermoplstics for injection molded conductive plastics.

Take my experienced word for it: you cannot simply mix the various fillers that are listed in these posts into a polymer melt and expect a suitable bond to form between the filler and polymer. Some fillers simply cannot work with some polymers. Most fillers that can be made compatible with the polymer require either a chemical coupling agent applied to the filler, or at least mixed with the polymer. It typically requires some trial-and-error experimentation to find a cost effective treatment, if one can even be found.

In addition, the mechnical properties of the polymer are altered with filler addition. The goal is normally to improve a specific property. However, this usually comes at the expense of some other property. Also, there is simply a physical limit on the filler load that a polymer can take before the mechanical properties are so comprimised as to make the composite material unsuitable for any practical use.

When the filler does not have good compatibility with the polymer, stress, including mechanical, thermal, electrical, water and/or chemical exposure can result in catastrophic failure. I don't think you would want a polymer object printed with a filler to crack or even shatter when dropped if the unfilled object is able to withstand the same drop unharmed. Liikewise a filled object to show moisture damage due to water absorption during a humid summer when the same unfilled object is unaffected.

I think you all get the point by now.

DrDave

martinprice2004 Wrote:
-------------------------------------------------------
> This is a very interesting development. I have
> been considering developing an extruder which adds
> filler to ABS filament in the extruder head. Ready
> made plastic filament just takes this one stage
> further, but does fix the plasic / filler ratio
> which means you won't be able to print parts with
> varying properties very easily.
>
> I think adding a non melting filler to ABS would
> potentially eliminate the shrinking / warping
> issues meaning that large cheap prints might be
> possible. I was thinking of carbon powder, wood
> flour etc. and using the plastic filament to drag
> the powder through the nozzle.
>
> One further problem is that if you use stone,
> glass etc. the brass nozzle would be wear very
> quickly.

I would be willing to BUY some rubbery filament for testing; I've got jobs for it right now! Please contact me at sham pine1 at slb.com (take out the spaces before mailing ;-)

Thanks,
Rod

You can buy elastic, extrudable filament right now from Orbi-Tech. It's called TPE (thermoplastic elastomer). It's just somewhat tricky to extrude, being elastic and all that... likes to make a pretzel after the driver bolt if there's any extra empty space there (which most extruder designs have.) But it works rather nicely if you can just get it pushed through the extruder.

I contacted Ori-Tech and they told me that they aren't willing to make me 1.75mm TPE filament, even if I bought 5 kg! Frustrating!

... when I've first contacted them for 3mm-filament five years ago there was exactly the same answer - they changed because of the huge demand ... so wait a while

---

Viktor
--------
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Call for the project "garbage-free seas" - [reprap.org]

Simba, what are the specific resins you're looking to extrude? I'm always interested in testing new materials, but knowing specific material properties is pretty important.

---

[haveblue.org]

Have Blue Wrote:
-------------------------------------------------------
> Simba, what are the specific resins you're looking
> to extrude? I'm always interested in testing new
> materials, but knowing specific material
> properties is pretty important.


Hey guys, sorry I haven't kept every as up to date as I wanted - mainly me and my partners in maker-crime were building the website Armani Creations to better be able to show off our progress with pictures and in a more official way if and when a product is ready. I am THRILLED to see how interested people are, and quite frankly surprised that magnetic and conductive filaments (my first guess) weren't at all that interesting compared to rubber, Delrin, and heavy-metal-weighted polymers. And tell me if I am not hearing you guys/girls correctly, conductive polymer and magnetic polymer don't seem to have much interest?

I will reveal just for the reprap community that the rubber is a styrene block copolymer, with an unusually safe and non-toxic profile. Obviously, if we go through the trouble of securing a minimum order to have rolls made we will want to sell it, but I've already decided to give everyone on this forum who asks a free sample when it is ready. We are in the final stages of setting up our own extruder.

Please do me a favor and goto the sticky post by michaelc so I know what diameter to start with...

Edited 2 time(s). Last edit at 10/11/2012 10:20AM by Simba.

Weldingrod1 Wrote:
-------------------------------------------------------
> I contacted Ori-Tech and they told me that they
> aren't willing to make me 1.75mm TPE filament,
> even if I bought 5 kg! Frustrating!


This is useful to know, though from personal experience with 3M and Adhesives Research, you need a minimum order about $25K-$30K....so yes, far more than 5 Kg :-S

DrDave Wrote:
-------------------------------------------------------
> Guys,
>
> I am a chemist with experience in development and
> testing of polymer thick film "inks" (pastes) for
> electronics applications.
Me too . I worked in the conductive polymer lab at University of Maryland for 5 years. I'm glad you pointed out some of the issues and agree with you completely. One of the inventions coming out of our lab was a conductive latex with exfoliated graphene (now used for heating driveways in winter). Also as a rule, I found that drying conductive paints is far far more effective than a conductive polymer that relies on percolation theory....but just because you haven't seen it work well yet, doesn't mean it hasn't been done. On the aspect of long-term erosion of contact due to oxidation there are also solutions we found for that...

Here is the trick: We use conductive filler, but not powder in our polymer. We've used quantum tunneling to our advantage.

---

Measure once, Cut twice, Print 3 times.

PomeroyB Wrote:
-------------------------------------------------------
> Very cool, Simba! Are you running it through an
> extruder with a hobbed bolt? Does the 400% stretch
> affect the way it is pulled through?

The 400% stretch only applies when the polymer is thinner than about 0.5mm. At 3 mm there is practically 0% stretch. It's a weird material, but more easily understandable once you play with it. I will put up a video by the weekend.

I think I finally understand hobbed bolt: [www.lulzbot.com] ?
Then no, we are using a plastistruder from prusa as the main testbed and I don't think that the designs will differ much (especially for rubber) where the friction is naturally high to begin with.

Edited 1 time(s). Last edit at 10/10/2012 12:21PM by Simba.

i agree, however ... i guess all in the community are working with non patent stuff and hopefully nobody wants to patent to the extent of driving prices up the wall or something.

so then again, i have yet to finish my machine ... and i like to know ... how are the experiments so far?

any nice good and bad videos to share ... i love them videos showing good and weird results

DrDave Wrote:
-------------------------------------------------------
> Guys,
>
> I am a chemist with experience in development and
> testing of polymer thick film "inks" (pastes) for
> electronics applications. Also, development work
> (resulting in a patent) on making oxidized metal
> poweders highly concuctive for use as conductive
> fillers in various thermoplstics for injection
> molded conductive plastics.
>
> Take my experienced word for it: you cannot simply
> mix the various fillers that are listed in these
> posts into a polymer melt and expect a suitable
> bond to form between the filler and polymer. Some
> fillers simply cannot work with some polymers.
> Most fillers that can be made compatible with the
> polymer require either a chemical coupling agent
> applied to the filler, or at least mixed with the
> polymer. It typically requires some
> trial-and-error experimentation to find a cost
> effective treatment, if one can even be found.
>
> In addition, the mechnical properties of the
> polymer are altered with filler addition. The goal
> is normally to improve a specific property.
> However, this usually comes at the expense of some
> other property. Also, there is simply a physical
> limit on the filler load that a polymer can take
> before the mechanical properties are so
> comprimised as to make the composite material
> unsuitable for any practical use.
>
> When the filler does not have good compatibility
> with the polymer, stress, including mechanical,
> thermal, electrical, water and/or chemical
> exposure can result in catastrophic failure. I
> don't think you would want a polymer object
> printed with a filler to crack or even shatter
> when dropped if the unfilled object is able to
> withstand the same drop unharmed. Liikewise a
> filled object to show moisture damage due to water
> absorption during a humid summer when the same
> unfilled object is unaffected.
>
> I think you all get the point by now.
>
> DrDave
>
> martinprice2004 Wrote:
> --------------------------------------------------
> -----
> > This is a very interesting development. I have
> > been considering developing an extruder which
> adds
> > filler to ABS filament in the extruder head.
> Ready
> > made plastic filament just takes this one stage
> > further, but does fix the plasic / filler ratio
> > which means you won't be able to print parts
> with
> > varying properties very easily.
> >
> > I think adding a non melting filler to ABS
> would
> > potentially eliminate the shrinking / warping
> > issues meaning that large cheap prints might be
> > possible. I was thinking of carbon powder,
> wood
> > flour etc. and using the plastic filament to
> drag
> > the powder through the nozzle.
> >
> > One further problem is that if you use stone,
> > glass etc. the brass nozzle would be wear very
> > quickly.

hi,
I am interested in speaking with you about your conductive filament. I have a project that I really need that for. How can I get in touch?

flowbear Wrote:
-------------------------------------------------------
> hi,
> I am interested in speaking with you about your
> conductive filament. I have a project that I
> really need that for. How can I get in touch?


I always read my PM's.

Simba Wrote:
-------------------------------------------------------
> Have Blue Wrote:
> --------------------------------------------------
> > Simba, what are the specific resins you're
> looking
> > to extrude? I'm always interested in testing
> new
> > materials, but knowing specific material
> > properties is pretty important.

> I will reveal just for the reprap community that
> the rubber is a styrene block copolymer, with an
> unusually safe and non-toxic profile.


I was hoping for a bit more detail along the lines of "we're using Kraton G1652 E". I'm not a big fan of 'secret sauce' materials.

---

[haveblue.org]

Of course, neither am I, but as is always the case with rep-rappers I would like to - and promise to - release the plans, sources, and methodology once there is a final 'product' There are several good reasons to do this when working on something that is more that just a small personal hobby.

1) We like to give very, very, (did I say very) specific suggestions on details, its only in our nature as makers. I'm trying to keep the conversation at the high level, '20,000 foot view' so we don't 'miss the forest for the trees'. Right now we are talking about different materials, and that is great, and anyone can get in on such a conversation. As soon as we talk about specific polymers that short cuts the conversation from "I would like Delrin or Nylon" to "why did we focus on polymer X again?"

2) The materials keep changing weekly because the project is at such an early stage, as we test and eliminate. I think it would be bad form to commit to one thing and then change it unpredictably.

3) I want to eventually do a group-buy to get a manufacturer to make us the polymer so we can try it. This means I'm going to spend money I don't have ordering a sample run of 300lb or more polymer at first just to get people interested. So assuming there is some big-name, closed-source polymer manufacturer reading the forums, I don't want them to pre-empt our ideas at reprap. They can copy it once we establish it here first : )

What do you think?

FYI, saying that I am using Kraton is almost giving away the recipe already. They only manufacture one kind of polymer that makes sense for this purpose. Styrene, butadiene, styrene block copolymer (SBS). We did not add anything yet, but might have to eventually to improve form-ability since it is sometimes too tough a material to extrude. BTW, G1652 works like hot glue. It is too weak and lacks dynamic range. It also only comes with talc (dust). We have a lot more testing to do. But that is where we started, in fact, so very very good guess.

Just an update for everyone. We've been contacting the world of thermoplastic rod manufacturers to try and get a custom order made. This is where having a company facade & website is great because they take us seriously, whereas before they wouldn't ever reply. Two companies said no (or didn't reply) after reviewing specs, and one said yes (all are in Ohio). So we may be getting the polymer made in the next month! It may make a great stocking stuffer for the folks who replied above for samples testing.

In case that one manufacturer falls through, or just takes too long, we are building our own filament extruder with built in mixer. I don't have time to put up plans right now, nor it is the focus of our project, but the cool part is the ability to mix with the same system. The way it works is a nozzle with cooling zone fits into a 3/4" black pipe. That pipe has a 3/4" auger screw drill bit (18") as you've seen in other designs. Then the pipe has a very large barrel of 2" pipe that is used as a mixing region. The mixing is done simply by pulling the auger screw back into the large pipe, so the extrusion barrel has no screw auger within it, and the plastic has no force to move forwards. Instead it recirculates (very, very slowly).

The auger is driven by a 360:1 worm geared DC motor. The heating is done using Nichrome wrapped around (1200 watt's of heat worth) around both barrels. In this way we expect to get higher throughput and consistency (more heat, larger area). The regulation is done with pololu maestro It is plugged into 120 VAC, connected @ powerswitch tail relay system, with standard thermister feedback. For safety, everything is vented outside with a custom laminar flow hood and window-prop piece of plastic with outdoor vent.

I have also been reviewing the safety of all kinds of polymers. I will post in another thread.

Hey Simba,

What diameter will you be shipping to your beta testers? I know you use 1.75 so if that's the case then I'd like to go ahead and start getting setup for it.

Also in regards to your heavy filament approximately how much (in %) filler will you be using and what is the expected specific gravity?

---

-Tom

We have hit a lot of resistance to manufacturers making the infill metal for us. We will make test ones ourself. A machine like Prusa can use both 1.75 and 3mm (though I'm not sure if people realize this). For most, we can output either, but for rubber, more than likely it will be 3mm, becuase you need a certain amount of stiffness to be able to push a wire.

Right now we have two proposed designs. % fill will be between 40% and 50% and the total specific gravity will be between 2.2 and 3. Higher than this (up to 7) can be achieved but will cost so much more than people are willing to pay. Unless you can think of a particle that weights 10X water and costs only a few bucks a pound, the per-volume weight increases dramatically as well!

Are there any filaments out right now that have a Durometer between 75 and 85?

Thanks

I wanted to specify the durometer I am referring to is on the A scale.

I would say that Orbi-Tech's TPE is somewhere in that area. I don't have any real numbers, but I would estimate that from handling the TPE and Shore A 70 and 90 O-rings. Just a guess, though, I might be wrong.

Oh, and someone was talking earlier about the possibility of getting that in 1.75 mm. I don't think it would work even if it was available. I'm pretty sure it would be impossible to feed when made so thin. It's already pretty hard to feed at 3 mm and at 1.75 mm it would be a lot more flexible.

Happy Thanksgiving Preview!

[www.youtube.com]

*Note what is special about these filaments compared to TPE is that they have a stronger difference between 3mm filament and 0.5mm-1mm extrusions. They will be easier to push. If you have a 5 mm distance between bolt and hot-end entrance, it could work for you. More testing to be done.

---

Measure once, Cut twice, Print 3 times.

I would love to try new print materials.

---

football

Interesting reading about conductive :

A Simple, Low-Cost Conductive Composite Material for 3D Printing of Electronic Sensors.

Quote
from the paper
This advance in low-cost 3D printing with offer a new paradigm in the 3D printing field with printed sensors and electronics embedded inside 3D printed objects in a single build process without requiring complex or expensive materials incorporating additives such as carbon nanotubes.

Quote
dzach
A Simple, Low-Cost Conductive Composite Material for 3D Printing of Electronic Sensors

I like it! I wonder if it can be electroplated...

Hi Simba, Came across your post for the first time, seems very interesting.

Would luv to test it. keep us all posted

Simba Wrote:
-------------------------------------------------------
> Of course, neither am I, but as is always the case
> with rep-rappers I would like to - and promise to
> - release the plans, sources, and methodology once
> there is a final 'product'.

Thanks, Simba - that's fantastic! I'm limited to running 1.75mm filament, and my machine requires a fairly high flow rate due to the long heating chamber. Hence my interest in specific material parameters.

Have you looked at polyester based elastomers rather than SBS by any chance? That's what Stratasys E20 elastomer filament was based on years ago, but I was never able to determine which specific resin they used. I believe it was based on Jan Helge Bøhn's research at Virginia Tech, but he never responded to my inquiries on the material:
[www-rp.me.vt.edu]
[utwired.engr.utexas.edu]

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[haveblue.org]