Hand Moldable Plastic Review

[MrAl]

Hello there,


I came across a type of plastic which when heated up a little can be molded into any shape just by hand, similar to modeling clay only this is actual plastic. I figured this would be beneficial to hobbyists and others for creating quick prototypes or even for longer term usage.

The chemical name of the plastic is:
polycaprolactone (PCL) thermoplastic.

It comes in a variety of brand names so if you look it up on the web you can find a brand name and investigate prices and quantities available and find many web sites with a lot of info on how to use it and what it can be used for. However, it is very easy to use. It can be heated with hot water and then kneaded by hand and formed into just about any shape. On the web i have seen motor mounts and custom motor shaft couplers for example, but lots and lots of other things too...almost anything that can be made out of plastic.

There is one catch, and that is that whatever it is to be used for can not get too hot. The stuff starts to soften around 130 degrees F and that is quite low for some electronic work so it wont work for things that get hot like power resistors and heat sinks. It will probably melt and pull apart.

My first test was making handles for a binder clip. All i did was heat some water to boiling, pour some of the plastic beads (the stuff comes in beads but i think other shapes too) into a hot and cold paper cup, pour the hot water in (it was around 200 degrees F by then) and then wait about 30 seconds or so. What happened was the beads melted but remained together in a clump, after which i could push them together with a hemostat and then lift the whole blob out of the water and start to mold it by hand. I pulled off two pieces of the stuff (like pulling taffy) and made two small finger grips for the binder clip. I then let it sit for about 15 minutes and the plastic became hard. The binder clip was then much easier to open having the finger grips.
That was just a test to see how the stuff worked in general. I also made a simple 'stick' like structure just to be able to test it to see how much it bends under force once it cools. The stick was about 3.5 inches long and varied in thickness from about 3/16 inch thick at one end to about 1/4 inch at the other end, and was 1/2 inch wide. Clamping 1/2 inch of the stick to a bench and applying about 1 pound of force on the other end caused it to bend by about 1/8 inch ad the force end. That means it is not super hard plastic but it's not super soft either, it's somewhere in between.

Other things i have seen made on the web were:
Circuit board standoffs (the stuff is electrically non conductive)
Specialized nuts for metal bolts (maybe nylon too)
Custom motor shaft couplers (although probably only for low speed stuff unless you find a way to balance it)

This stuff was originally suggested for use by Mickster, who answered a question i had about ideas for attaching lanyards to devices that didnt come with a lanyard hole. I have since then made an attachment to a small USB device that allowed it to hold a lanyard onto the end of the device, as well as another holder for holding a SD card into a USB card reader so it wont slip out during transport.

I can post some pictures if anyone is interested. And if anyone reading this is not interested, you dont know what you are missing

 

[wannaBinventor]

I'm pumped up to hear this!

 

[MrAl]

I'm pumped up to hear this!

Hi,


Do you mean you want to see some pics?

 

[3v0]

Pictures please.

 

[KJ6EAD]

Examples from Plastimake:

https://www.plastimake.com/examples

 

[3v0]

I can't say I like the price but I am a tight wad.

 

[picbits]

We have it over here - its called Polymorph. I've been using it for around 5 years - great stuff. Good for making brackets and repairing stuff in a hurry !

I'll try and get some pics of it.

 

[picbits]

Does it look like this stuff ?

 

[MrAl]

Hi,


That stuff looks very similar but not exact. Perhaps the manu's vary the pellet size and shape. My pellets are more like a flat ball shape. It's a different brand name. It must the same stuff however, the basic type of plastic.

I'll try to get some pics up soon.

More tests ive done so far:
1. I noticed that even when it is in a thin layer (like paper thin or maybe two layers of paper thickness) it is very strong once it cools. Once it cools you probably can not rip it apart like paper even if it is just as thin. It would take a lot to rip it i think. The part i made was a strap that might usually be made out of leather or similar or maybe cord. The strap is thin and even thinner in some places yet it is very strong.
The only thing to worry about is if it touches anything too hot it will literally melt apart, so that's something to always keep in mind.
It's better than hot glue however, much better.
2. About the heating up, after i made the 'strap' and wrapped it around the device while it was still warm i didnt quite squash the two ends together very well, so when i lifted one end of the strap it came right up, like opened up the 'loop' the strap made. So what i tried was i took a soldering iron and plugged it in, and a few seconds later (no more) i rubbed it across the surface of one end of the strap and it softened the plastic again only in the area at the end of the strap. I was then able to press that end to the other end and that closed the loop. The strap, that started out as just a strap like a belt, was now one continuous piece! And it would be very hard to remove without heat.
3. Just for some small experimenting, i made a couple of clamp surface protectors. These are just two pieces of plastic that go on the two faces of the (or any other) clamp. When the clamp is used on furniture it doesnt hurt the surfaces as much because the plastic helps to protect it (to some degree). Actually the protectors broke off a while back so i was really just replacing them. But the way it worked was the stuff was softened and then simply folded around the ends of the clamp, one small piece for each end. Pressing the pieces against the ends means the stuff molds itself to the shape of the clamp ends, so it stays there once cooled.

Granted these are just small applications that dont mean much, but it's a way of learning how to best use this stuff. I find it is sort of like using hot glue only not as hot and when it cools it is actual plastic not some junk that's going to crack off.

Next im going to try the threads. The idea is to melt a piece that will fit the application and then wrap it around the bolt it is intended for. Then let cool and then unscrew the bolt, and we've got a piece of threaded material that can be used in the application. From what i have read so far, the threads end up pretty tight, like as if you had a nylon lock nut on the bolt. And also it might not hold up to repeated screwing in and out. But it will still be handy in those more permanent applications. Im giong to try this and see how hard it is to remove the bolt once it cools and how well it holds up to screwing and unscrewing several times.

I see a lot of potential uses for this stuff especially for a quick fix either temporary or permanent. It's a lot better than hot glue and also seems to be able to hold up better under stress because it is strong once cool. The only thing i dont like about it is that if it comes into contact with anything that could heat it up too much whatever that object is basically becomes a blob again I'll have to see how this works out over time. A good experiment would be to put an object made with this stuff on the dash of a car under the windshield and see how it holds up in the summer time when it gets hot in the vehicle.

 

[MrAl]

Hi again,


Here are a few pics of the experiment with the bolt molded into the plastic material.

The bolt is embedded into the material by about 3/4 inch so it's pretty deep.
The size of the bolt is M5-0.8 and is 2 inches long overall, with 3/4 inside the blob of plastic.
The amount of material needed to create this was about 1 tablespoon.
I slightly oiled the threads of the bolt before molding.

After the stuff cooled, the bolt was stuck in a little but not too bad. It couldnt be removed by hand but with a phillips screwdriver it came out pretty easy. On screwing it back in, i was able to screw it in farther than it had molded threads to the bottom of the blob started to bulge out a little where the screw tip was trying to push through. It's hard to tell when the end of the threads occurs because there is no definite stop feel when screwing the bolt in with the screwdriver. Of course it could have been measured beforehand.
It felt like it could support some real weight, but i havent tried that yet.

A better idea would be to screw the bolt into a nut or even two nuts before molding, then mold right around the nuts. That would embed the nuts right into the plastic and make the threads more reliable, although they didnt seem too bad already even without that.
It was a little difficult to get the stuff around the bolt to fill in the thread so as to form good threads in the material. At first there was air trapped in the thread area so one side of the bolt was not touching the material but had a large air pocket. I had to remelt the material to get it softer to be able to mold it tighter around the bolt shaft. After that it worked pretty good.

Total time was about 10 minutes including heating the water in a cup in the microwave.

Oh yeah, the stuff sticks to some materials like other plastics when hot so dont use a styrofoam cup as it sticks to the inside and is a pain to get out. A regular paper hot&cold cup works better.

So the experiment was a success but the next time i would mold at least one nut inside the plastic too in order to make a better grade item.

I'll have to try to apply some weight to it next but i've read that people have made lots of hooks of different types so i dont expect it to warp too much over time with constant stress. Some plastics dont droop at first but then after hours, weeks, months they start to droop noticeably. I dont think this stuff does this, and an overnight clamping test showed that it does not squash due to constant pressure, at least not over a 24 hour period.

Of course more time would be required to do more tests for longevity in certain stressed applications. If you have any experience in these areas please post your results, thanks.

 

[leftfield95]

Polymorph reportedly has 580 kg/cm2 of tensile strength, but I haven't tested it to this degree.

Here's a repair I made using Polymorph on a Flymo grass cutter, its still working after a few months.

View attachment 66282
View attachment 66281
View attachment 66284
View attachment 66283

 

[ccurtis]

Thanks for the review! What are your thoughts on its machinability (can it be filed, cut with saw, drilled) and its use as a waterproof sealant for pipes?

 

[Mr RB]

You don't have to mess about with boiling water, you can use a heat gun (like with heatshrink tube).

Then you can heat just one part of the job and shape or work it, good for smoothing off the outer surface or re-working part of a shape.

 

[MrAl]

Hi again,

Leftfield:
Thanks for posting. It looks like it held up pretty well. I wonder how much stress it was getting in that application.

ccurtis:
It is somewhat machinable. I was able to drill it no problem, using a very low speed of about 300rpm. I would bet it could be sawed with a hand saw, not sure about a circular saw though as it may melt it as it goes. It does cut easily with a hack saw, but leaves the feathered edges as described next. Some edge feathering occurs during drilling too.

Filing is a little strange. I was not able to file it with a fine pitch file using light pressure and i couldnt use heavy pressure because the piece was at an odd angle for what it was being used for and was very small. However, i was able to file it with a more coarse pitch file used for thick metal or wood, and it did file but there was an after effect. The after effect is that the edge farthest from the files forward direction develops a feathered edge. That is, it looks like someone cut off a piece of Saran Wrap plastic food wrap and glued it to the far edge, so it hangs off the edge and looks like a very very thin piece of plastic not too wide but definitely present. It makes the job look unfinished even though it was just filed smooth. The rest of the surface shows the file marks but that's it, just like a filed piece of metal.
The feathers might be removed with a semi hot tool like a warm (not hot) soldering iron or a plastic welder tool not too hot and/or moved quickly across the material.

As i was working with it with the drill, saw, and metal files, it appeared to work almost like nylon only maybe a little softer.
The feathers are a little bothersome but not a significant problem unless you're looking for a really nice looking object and then you would want to smooth them with a hot tool or knife.

Cutting with a knife isnt too hard either. It seems easier to cut with the knife when it is cool than when hot. With a sharp razor knife i was able to cut through it with a lot of pressure but reasonable for the thickness and toughness of the plastic. It wasnt too hard but not super easy either. Again it's like cutting nylon only maybe a little softer.

 

[leftfield95]

Hi MrAl,

This was a quick repair I made to my dad's mower after the original locating pegs got sheared off, due to the blade bolt being too loose. The constant acceleration and the occasional grounding of the blade eventually sheared the hollow pegs off.
Now he checks/tightens the blade regularly so the shearing force applied to the repaired pegs will be less. But its cheap and simple enough to repair again if it does fail later.

If the Polymorph gets heated to a much higher temperature it seems to act more like hot melt glue and bonds to objects, but sets much harder when cooled. I don't know how well it would adhere to objects over the long term though.

I would have to describe it as more like Polythene than Nylon, but with a lower melting point.

Leftfield95.

 

[jpanhalt]

It is interesting stuff. If you substitute the esterial oxygen with a nitrogen, you get polycaprolactam, i.e., nylon (https://en.wikipedia.org/wiki/Polycaprolactam).

Caproic acid is just at the line between short-chain carboxylic acids that smell really bad (e.g. butyric acid) and those that barely have a smell. If you hydrolyze the PCL with a strong base (lye), you will get something that smells like a goat.

John

 

[Mickster]

Here's the thread which started off the discussion and MrAl's subsequent review of this very useful polymer:

https://www.electro-tech-online.com/threads/ideas-for-usb-device-lanyard-attachment.128991/

 

[MrAl]

Hi again,


I noticed that drilling creates a burr on the side opposite the start side. It wasnt so much as a feather as an actual burr. The burr has to be removed just like when working with metal. It can be cut off with a knife or probably melted with a hot tool like s warm soldering iron. Maybe a speed even slower than 300rpm would be good for drilling.
Also noticed that when i cut the burr off the hole closed up a little and might need redrilling.

LeftField:
I might have to try heating it up more sometime and see how it holds up. Right now im trying to follow the directions and see how it works that way. I wouldnt mind getting it to be harder sometimes too though.

jpanhalt:
Oh that's interesting i always wanted something that smelled like a goat

 

[MrAl]

Hello again,


I tested some of this stuff on the dashboard of the car. I stuck a small piece in the opening of a small key hider. The key hider is painted black on the outside. Rode around town for about 30 minutes, the part of the stuff that was touching the black part of the case had melted. The part that did not touch was not melted.
I then put the whole thing inside the black key hider case and closed it. Maybe another 15 minutes i opened the case and the small piece was completely melted but retained it's shape.

Thus we can see that this stuff is very heat sensitive. Had the piece been bigger it would have taken longer to melt in the sun on the dashboard of the car. It might actually survive inside the car if the sun could not heat anything close to it, well touching it. Anything that touches it can not get too hot.

It's really a shame that the temperature really limits what this can be used for. Probably indoors where the temperature doesnt go over 100 F too often. Of course it's still very good for making molds where you'd use it to pour a different material for casting like resin, as long as the resin doest get too hot during the cure (limit the amount of catalyst added to the resin to keep heat down).

 

[jpanhalt]

Its heat sensitivity could be an advantage. I use Woods metal to fill thin-walled tubing that I need to bend rather sharply. This moldable plastic might serve the same purpose and be cheaper.

John