Sciencemadness Discussion Board

'Sugru': anyone any experience with this?

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blogfast25 - 30-5-2016 at 15:56

https://sugru.com/about

This playdough like, RT air curing material might have some limited applications in home labs.

"Bluetack meets RT cured silicone sealant", something like that...

j_sum1 - 30-5-2016 at 17:20

Looks pretty awesome.
I can think of a few things it could be useful for.
Is it actually silicon based or a silicone substitute? I couldn't tell from the website.

macckone - 30-5-2016 at 19:55

From the site, it is some kind of air cured silicone with a filler and color additive.
The exact composition is probably complex.

aga - 30-5-2016 at 22:37

Science fiction become fact, yet again.

"The Mote in God's Eye" by Larry Niven and Jerry Pournelle.

An excellent read.

hissingnoise - 31-5-2016 at 00:32

Deja vu all over again! :P

http://www.sciencemadness.org/talk/viewthread.php?tid=13257#...

blogfast25 - 31-5-2016 at 06:54

Quote: Originally posted by hissingnoise  
Deja vu all over again! :P

http://www.sciencemadness.org/talk/viewthread.php?tid=13257#...



Oooopsie.

Oogoo, the DIY Sugru

Muffn Man - 31-5-2016 at 07:56

Check this out:
http://www.instructables.com/id/How-To-Make-Your-Own-Sugru-S...

"Corn starch and clear silicone caulk"

[Edited on 31-5-2016 by Muffn Man]

blogfast25 - 31-5-2016 at 08:25

Sugru is likely to use something a bit more sophisticated than corn starch as filler. Precipitated or pyrogenic silica (possibly silane treated) e.g., both of which are preferred fillers/reinforcing agents for silicone elastomers.

A bit of water getting into your 'Oogoo' and I think you can imagine the result.

Many of these 'instructables' are fairly useless Google fillers, designed to be ad carriers.

[Edited on 1-6-2016 by blogfast25]

aga - 31-5-2016 at 09:01

i bought the multi-coloured 8-pack this morning.

Should arrive well before the universe ends, so what would you like done to it ?

blogfast25 - 31-5-2016 at 11:34

Quote: Originally posted by aga  
i bought the multi-coloured 8-pack this morning.

Should arrive well before the universe ends, so what would you like done to it ?



As someone who worked in elastomer R&D for about 10 years, I'd be most interested in post-cured tensile strength and elongation at break but these are NOT easy to measure accurately at home level.

Also interesting: these same properties after artificial ageing: e.g. after 24 h @ 100 C in air.

Also interesting: tension set. A uniform sample is stretched to 50 % for 24 h. Then the residual deformation is measured, after the tension is released. It's a rough measure of long term elasticity.

Or liquid absorption: how much does a slab of cured Sugru absorb over a 24 h period of a given liquid? Water, kerosene, xylene are all good fluids to test the material's resistance to.

Elastomers are interesting materials, both chemically and physically!

[Edited on 31-5-2016 by blogfast25]

aga - 31-5-2016 at 11:40

Would need to get a clue as to the possible extension length before rigging up something that could possibly be anywhere near accurate.

That's 1 knackered.

7 to go and have not even got them yet !

[Edited on 31-5-2016 by aga]

blogfast25 - 31-5-2016 at 11:54

Quote: Originally posted by aga  
Would need to get a clue as to the possible extension length before rigging up something that could possibly be anywhere near accurate.

That's 1 knackered.

7 to go and they have not even got them yet !


ASTM standards prescribe dumbbell specimens for tensile testing:

http://www.ptli.com/testlopedia/subs/Tensile-rubber-sample.a...

You could cut these out from a moulded sheet of Sugru, with a pair of scissors. You could then get a rough idea of E@B by simply stretching the dumbbell manually until it snaps.

Of course you can use smaller sized dumbbells too.

How much of the stuff have you got?

[Edited on 31-5-2016 by blogfast25]

aga - 31-5-2016 at 11:57

None yet.

I ordered the 8-pack, different colours.

blogfast25 - 31-5-2016 at 12:03

Quote: Originally posted by aga  
None yet.

I ordered the 8-pack, different colours.


I meant: how much are you supposed to receive?

http://www.ptli.com/testlopedia/subs/Tensile-rubber-sample.a...

Wow. £10 for 25 g. Cheap it ain't!

[Edited on 31-5-2016 by blogfast25]

aga - 31-5-2016 at 12:24

i bought from the sugru.com site.

In teensyweensy writing it says 8x 5g packs.

No idea if the entire pack, including packaging weighs 5g or if the product weighs 5g.

blogfast25 - 31-5-2016 at 12:42

Quote: Originally posted by aga  
i bought from the sugru.com site.

In teensyweensy writing it says 8x 5g packs.

No idea if the entire pack, including packaging weighs 5g or if the product weighs 5g.


Net weight, no doubt.

Enough for 8 dumbbells! :D

battoussai114 - 31-5-2016 at 17:04

You could play around and figure what filler they're using... I'm pretty sure there are solvents that could take the uncured elastomer away in a solid-liquid extraction, but I can't name one right now, and once the elastomer is out maybe you could put a sample of what is left in piranha solution to get rid of any organics and then check if there's some form of silica left.

----Edit----


Seems talc is, at least one, of the fillers: https://sugru.com/pdfs/msds-usa.pdf

[Edited on 1-6-2016 by battoussai114]

blogfast25 - 31-5-2016 at 18:05

Quote: Originally posted by battoussai114  

----Edit----


Seems talc is, at least one, of the fillers: https://sugru.com/pdfs/msds-usa.pdf



Two functional silanes and a polysiloxane as base elastomer: quite sophisticated... Definitely more sophisticated than homemade 'Oogoo'.

Thanks for that!

[Edited on 1-6-2016 by blogfast25]

Maker - 1-6-2016 at 00:46

Quote: Originally posted by blogfast25  
Quote: Originally posted by aga  
i bought the multi-coloured 8-pack this morning.

Should arrive well before the universe ends, so what would you like done to it ?



As someone who worked in elastomer R&D for about 10 years, I'd be most interested in post-cured tensile strength and elongation at break but these are NOT easy to measure accurately at home level.

Also interesting: these same properties after artificial ageing: e.g. after 24 h @ 100 C in air.

Also interesting: tension set. A uniform sample is stretched to 50 % for 24 h. Then the residual deformation is measured, after the tension is released. It's a rough measure of long term elasticity.

Or liquid absorption: how much does a slab of cured Sugru absorb over a 24 h period of a given liquid? Water, kerosene, xylene are all good fluids to test the material's resistance to.

Elastomers are interesting materials, both chemically and physically!

[Edited on 31-5-2016 by blogfast25]

From the Formerol website:
Shore A hardness: 70
• Density: 1.3g/cm3
• Tensile strength: 1.89 MPa
• Youngs Modulus: 5.59MPa
• Strain-to-failure: 211%
• DIN Abrasion Resistance: 24% ARI index
• Williams Plasticity: 160mm
• Electrical Resistivity
• Surface 1.40 x 1014 Ohms
• Volume 2.55 x 1014 Ohms

Muffn Man - 1-6-2016 at 04:35

I don't disagree that many Instructables are junk. This one, however, doesn't strike me as being one of them. Also, I was not suggesting that Oogoo would be technically equal to Sugru. I wanted to present a community of Do-It-Yourselfers and experimenters a VERY cheap and reasonably similar alternative to Sugru.

If you Google "Oogoo", you will find many pages not affiliated with Instructables where folks have tested the mixture with satisfactory results.

[Edited on 1-6-2016 by Muffn Man]

blogfast25 - 1-6-2016 at 07:23

Quote: Originally posted by Maker  

From the Formerol website:
Shore A hardness: 70
• Density: 1.3g/cm3
• Tensile strength: 1.89 MPa
• Youngs Modulus: 5.59MPa
• Strain-to-failure: 211%
• DIN Abrasion Resistance: 24% ARI index
• Williams Plasticity: 160mm
• Electrical Resistivity
• Surface 1.40 x 1014 Ohms
• Volume 2.55 x 1014 Ohms


What jumps off the page here is the very low value of tensile strength (T.S. = 1.89 MPa). Although silicone elastomers aren't renowned for high T.S. values, 10 MPa and higher can quite easily be achieved. The E@B of 211 % is correspondingly low too.

aga - 1-6-2016 at 11:52

Behold !

The first mock-up prototype StretchFast25 Stretchy-Snappy-o-Meter.

StretchFast25.jpg - 78kB

The bar to the Left will be welded to the substrate, and have a clamp to grab hold of the sample.

The bar in the middle will be welded to a Nut on the thread-screw and also have a clamp to grab the other end of the sample.

This Nut will be part of an anti-backlash arrangement to reduce/eliminate 'throw' when the sample snaps (they should end up pretty much at the right place after the snap).

That's basically two nuts and a springy thing.

1. The test subject is clamped in.

2. With a mirror behind the plastic ruler (should be Rule, but why argue) we can get some degree of parallax elimination to calibrate zero.

3. Turn the thread-screw little by little whilst wearing an insane and daemoniacal grin, reciting any remembered E.A. Poe, and the subject slowly stretches.

4. Eventually, he snappeth !

5. Read off the elongation at snap-point.

6. Post results in this thread.

In the photo i just grabbed the closest thing at hand to stand in place of the actual test subject, subergoob or whatever it is.

Other things such as the width of the starting strip and width at certain elongation points can be measured.

Any other suggestions for measurable things ?

[Edited on 1-6-2016 by aga]

blogfast25 - 1-6-2016 at 14:01

Quote: Originally posted by aga  
Behold !

The first mock-up prototype StretchFast25 Stretchy-Snappy-o-Meter.



The bar to the Left will be welded to the substrate, and have a clamp to grab hold of the sample.

The bar in the middle will be welded to a Nut on the thread-screw and also have a clamp to grab the other end of the sample.

This Nut will be part of an anti-backlash arrangement to reduce/eliminate 'throw' when the sample snaps (they should end up pretty much at the right place after the snap).

That's basically two nuts and a springy thing.

1. The test subject is clamped in.

2. With a mirror behind the plastic ruler (should be Rule, but why argue) we can get some degree of parallax elimination to calibrate zero.

3. Turn the thread-screw little by little whilst wearing an insane and daemoniacal grin, reciting any remembered E.A. Poe, and the subject slowly stretches.

4. Eventually, he snappeth !

5. Read off the elongation at snap-point.

6. Post results in this thread.

In the photo i just grabbed the closest thing at hand to stand in place of the actual test subject, subergoob or whatever it is.

Other things such as the width of the starting strip and width at certain elongation points can be measured.

Any other suggestions for measurable things ?

[Edited on 1-6-2016 by aga]


Nice. Shame it can't actually measure force at breaking point.
Quote: Originally posted by blogfast25  

Also interesting: these same properties after artificial ageing: e.g. after 24 h @ 100 C in air.

Also interesting: tension set. A uniform sample is stretched to 50 % for 24 h. Then the residual deformation is measured, after the tension is released. It's a rough measure of long term elasticity.

Or liquid absorption: how much does a slab of cured Sugru absorb over a 24 h period of a given liquid? Water, kerosene, xylene are all good fluids to test the material's resistance to.

aga - 1-6-2016 at 14:05

Fish-scale at the left, clamped to fixed support, subject clamped to fish-scale part ?

Dunno.

Will await both the subaru and any suggestions.

[Edited on 1-6-2016 by aga]

blogfast25 - 1-6-2016 at 14:39

Quote: Originally posted by aga  
Fish-scale at the left, clamped to fixed support, subject clamped to fish-scale part ?

Dunno.

Will await both the subaru and any suggestions.

[Edited on 1-6-2016 by aga]


'On paper' the torque needed to turn 'Twisty bit' (and thus extend the sample) is proportional to the tension (force) in the sample. Unfortunately poorly defined friction between the nuts and 'Twisty bit' would make that relationship very inaccurate.

[Edited on 1-6-2016 by blogfast25]

aga - 3-6-2016 at 08:20

'ows about adding this jobbie into the mix :

fishscale.JPG - 241kB

Just €5 from the chinese shop !

So, when the 'twisty bit' gets turned, the rack stretches the subject, those scales measuring the diabolical stretchy forces unponst said subject.

It appears to have a kind of 'ratchet' function where it records the max pulling force.

blogfast25 - 3-6-2016 at 10:25

Looking good! :)

aga - 3-6-2016 at 15:20

As it is said, so shall it be.

Any clues pertaining to the actual Max distance stuff Can stretch ?

I got to pick some bits of steel out of the pile and cut 'em to length.

The 'twisty bit' is a metre long, so about 80cm is the max i can do.

Edit:

... without special effort.

[Edited on 4-6-2016 by aga]

blogfast25 - 3-6-2016 at 15:55

Quote: Originally posted by aga  


Any clues pertaining to the actual Max distance stuff Can stretch ?


[Edited on 3-6-2016 by aga]


Acc. information upthread, elongation break is about 211 %. A specimen with active length of say 5 cm would stretch to about 15 cm and then snap.

Presenting: The StretchFast25

aga - 4-6-2016 at 08:20

Tadaaa !

built_refs.jpg - 77kB

The sample gets clamped in, the crank turned to get the teensiest bit of tension in the sample, then the elongation scale is zeroed, the force scale tared and the sample length measured, then start turning the handle until it snaps.

Here's a small rubber band before and after:-

Starting length of sample : 40mm
Distance travelled by the moving clamp at snapping point : 118mm
(i.e. snapped at total length 158mm)

bandbefore.JPG - 202kB snapped.JPG - 158kB

The force scale keeps going into 'lock' so not sure what the Force was at snapping point (it locked at 0.09kg). Probably some feature to stop fishermen lying about Weight as well as Length !

Will find out how that is disabled.

[Edited on 4-6-2016 by aga]

blogfast25 - 4-6-2016 at 08:48

@aga:

That looks really great! :)

Make sure the top clamp is lubricated with respect to the sliding bars, to reduce friction errors.

Have you thought about the curing conditions of the Sugru?

aga - 4-6-2016 at 08:49

Found it - just press the Tare button for a while and it says 'L-Off' which means the lock function is disabled.

Start length: 29mm
Elongation: 62mm
Snap length: 91mm
Force: 0.36kg

blogfast25 - 4-6-2016 at 11:18

Quote: Originally posted by aga  
Found it - just press the Tare button for a while and it says 'L-Off' which means the lock function is disabled.

Start length: 29mm
Elongation: 62mm
Snap length: 91mm
Force: 0.36kg


So:

$$E@B=\frac{91-29}{29} \times 100\:\text{%}=214\:\text{%}$$

For Tensile Strength you need to know the cross section A of the sample:

$$TS=\frac{F}{A}$$

With force F in Newton and A in m2.

aga - 4-6-2016 at 11:27

Quote: Originally posted by blogfast25  

For Tensile Strength you need to know the cross section A of the sample

Which cross-section ?

The one before it gets stretched or the one at the breaking point ?

blogfast25 - 4-6-2016 at 12:12

Quote: Originally posted by aga  


The one before it gets stretched or the one at the breaking point ?


The Actual, Real TS is the one using the cross-section at breaking point. But for reasons of simplicity we use the one before it gets stretched because that one is easy to measure.

Both are easily related anyway because rubber is basically incompressible: its density hardly changes when compressed or elongated.

If the sample had a cross-section A<sub>0</sub> and initial length L<sub>0</sub> then its volume is:
$$V=A_0L_0$$
Now we stretch it to L, its cross-section decreases to A:

$$V=AL=A_0L_0$$

So:

$$A=A_0\frac{L_0}{L}$$
Using that, the Real TS and the one calculated based on A<sub>0</sub> can be related easily.


[Edited on 4-6-2016 by blogfast25]

aga - 4-6-2016 at 12:41

These bands are a square section.

These digital vernier calipers say it's 1.34mm x 1.58mm, based on measurement at the point where there is a slight resistance to movement between the jaws.

Not easy to measure this way, as the rubbery stuff obviously 'gives' when you try to clamp it.

How do they measure elastic stuff professionally ? Optics ?

blogfast25 - 4-6-2016 at 14:33

Quote: Originally posted by aga  
These bands are a square section.

These digital vernier calipers say it's 1.34mm x 1.58mm, based on measurement at the point where there is a slight resistance to movement between the jaws.

Not easy to measure this way, as the rubbery stuff obviously 'gives' when you try to clamp it.

How do they measure elastic stuff professionally ? Optics ?


We used to use a digital vernier type measurement, with a 'soft touch'. Rubbers inevitably give, so it's a bit approximate.

Those values and the 0.36 kg give TS = 1.7 MPa. That sounds a little low even for a 'cheap and dirty' rubber band but it is what it is, I guess...

Try one of these wider 'natural colour' rubber bands for parcelling etc?

[Edited on 4-6-2016 by blogfast25]

aga - 4-6-2016 at 14:48

Quote: Originally posted by blogfast25  
Try one of these wider 'natural colour' rubber bands for parcelling etc?

It is safe to assume that several <strike>victims</strike> samples will be tested over the next few days.

Need to get a feel or the process before the shugargoo arrives.

Edit :

On which point, how would you like the Victims treated before being subjected to the Rack ?

The usual Acid Bath, or perhaps some fiendishly exotic scheme ?

[Edited on 4-6-2016 by aga]

blogfast25 - 5-6-2016 at 05:59

Quote: Originally posted by aga  

It is safe to assume that several <strike>victims</strike> samples will be tested over the next few days.

Need to get a feel or the process before the shugargoo arrives.

Edit :

On which point, how would you like the Victims treated before being subjected to the Rack ?

The usual Acid Bath, or perhaps some fiendishly exotic scheme ?



As you said, first get a feel for the 'Rack'.

Analyse several mundane samples.

Get a feel for repeatability by analysing the same sample several times.

Even with professional equipment:

https://www.youtube.com/watch?v=9N5SS8f1auI

... expect considerable spread on the TS and E@B values, for a given material.

[Edited on 5-6-2016 by blogfast25]

aga - 5-6-2016 at 12:39

Quote: Originally posted by blogfast25  
Even with professional equipment:

https://www.youtube.com/watch?v=9N5SS8f1auI

The pros clearly have Slidy bits on show, yet at 0:51 in the video a small Twisty bit is visible at the bottom-left of the machine.

I suspect there's a Big Twisty bit hidden in the casing.

aga - 6-6-2016 at 12:23

The stuff arrived today.

pack.JPG - 145kB contents.JPG - 186kB open.JPG - 194kB

Data from the packaging ...

Storage: 21 C or less. Keeping unopened packs in the fridge makes them last up to 3 times longer .

Cures up to 3mm thick in 24 hours

Temperature resistant up to 180 C, down to -50 C

'salt water proof'

an electrical insulator.

It turns into a flexible silicone rubber

Contains:-

Methyltris(methylethylketoximine)silane
3-aminopropylethoxysilane

--------------------------------

It feels like wet blu-tack, very similar to putty.

The smell is unusual, yet not totally unfamiliar.

I can imagine computers inhaling it to give then an 'all 1111s' high.

After a few big whiffs of it there was a noticeable feeling of it banging about in my sinuses. This settled after 5 minutes to become a dull ache where my jaw pivots on the right hand side.

The solvent sticks to skin (mine at least) as does a very small fraction of the blue colouring.

It has been flattened out into a rough dumb-bell shape and left to cure.

blogfast25 - 6-6-2016 at 14:14

@aga:

Might be better to roll pin a small squarish slab of uniform thickness (2 - 3 mm, to be measured accurately post-cure), cure it and then cut out dumbbells with a pair of scissors and a pattern?

[Edited on 6-6-2016 by blogfast25]

aga - 6-6-2016 at 15:37

Yep. Might be, but i didn't.

Probably best to just open the pack, let it cure, then stretch the feck out of it.

Is there any reason for the cutting-out-a-shape part ?

e.g. an exact starting thickness/width ?

What does 'roll pin' mean ?
To me that is a (usually) small steel cylinder with a bit missing.

[Edited on 6-6-2016 by aga]

blogfast25 - 6-6-2016 at 17:06

Quote: Originally posted by aga  


1. Probably best to just open the pack, let it cure, then stretch the feck out of it.

2. Is there any reason for the cutting-out-a-shape part ?

3. e.g. an exact starting thickness/width ?

4. What does 'roll pin' mean ?
To me that is a (usually) small steel cylinder with a bit missing.



1. Not if you want values (TS and E@B) that are representative.

2. Just sounds easier to make reproducible shapes that way.

3. You'll always have to measure thickness after curing. Rubber is a visco-elastic material.

4. Sorry: rolling pin. Roll the Sugru like you would tart dough.

[Edited on 7-6-2016 by blogfast25]

aga - 12-6-2016 at 08:04

Had a bash at the stretchy-snappy-o-meter today with short lengths of heat-shrink tubing.

Results:

heatshrink.gif - 6kB

The cured sugru stuff then got it's turn, and came out at E@B = 75.2%, TS=1.6MPa

What to do with it next ? Hmm ...

acidnbase.JPG - 110kB

C'mon. Place yer bets !

blogfast25 - 12-6-2016 at 08:15

Quote: Originally posted by aga  
Had a bash at the stretchy-snappy-o-meter today with short lengths of heat-shrink tubing.



The cured sugru stuff then got it's turn, and came out at E@B = 75.2%, TS=1.6MPa



The results for the heat-shrink tubing 'sound right'.

But E@B = 75 % for the Sugru sounds very low. I wonder if your stuff has been fully cured. The curing chemical reactions are slow at RT. To complete cure, we used to add a short so-called 'post cure' for RT cured elastomers. In the case of Sugru, a mere 15 min @ 180 C (in a domestic oven) should complete the curing to a 100 % completion.

Nice work!

aga - 12-6-2016 at 08:24

El Sugrero has been curing for a few days, and RT at the mo is around 36C + during the day.

Will zap the next batches in the oven.

It feels quite odd, in that when you stretch it by hand, it has a range in which it stretches linearly, then at a certain point it is as if some internal fibres have gone as far as they can, and it resists further stretching.

The sulphuric sample is going green ...

What next ? Pre-treat, post-treat, stretchy-snappy ?
Burny, freezy ?

Edit:

7 samples left


[Edited on 12-6-2016 by aga]

blogfast25 - 12-6-2016 at 08:46

Quote: Originally posted by aga  

It feels quite odd, in that when you stretch it by hand, it has a range in which it stretches linearly, then at a certain point it is as if some internal fibres have gone as far as they can, and it resists further stretching.



Ideal elastomers have a stress v elongation curve like this:

Stress v elongation.png - 2kB

It fits your observation.

Apart from any chemical resistance tests, it could be interesting to stretch a sample at say 50 % for 24 h, then see how much it recovers on release That gives an idea of creep, an important property in sealing applications.

[Edited on 12-6-2016 by blogfast25]

aga - 12-6-2016 at 09:02

Quote: Originally posted by blogfast25  
stretch a sample at say 50 % for 24 h, then see how much it recovers on release

So, make Two identical samples, stretch one until it snaps, measure elongation, then stretch the second one to 50% of that for 24hrs, then see how long it is when released.

OK.

blogfast25 - 12-6-2016 at 09:40

Quote: Originally posted by aga  
Quote: Originally posted by blogfast25  
stretch a sample at say 50 % for 24 h, then see how much it recovers on release

So, make Two identical samples, stretch one until it snaps, measure elongation, then stretch the second one to 50% of that for 24hrs, then see how long it is when released.

OK.


Yup. From the residual elongation and initial length, calculate the Tension Set, the same way you calculate the E@B.

Also interesting: extend to say 50 % then stop extending and monitor stress. As a visco-elastic material its stress will reduce in time, aka stress relaxation.

aga - 12-6-2016 at 11:57

Quote: Originally posted by blogfast25  
its stress will reduce in time, aka stress relaxation.

Interesting. That is exactly what i saw when reading the stretch-o-meter : the force increased, reduced, then increased again while turning the handle as regularly as possible.

Up near the snapping point the force would go a bit ape, increasing a Lot before reducing a lot just before the snap.

blogfast25 - 12-6-2016 at 13:13

Quote: Originally posted by aga  

Up near the snapping point the force would go a bit ape, increasing a Lot before reducing a lot just before the snap.


Which is why commercial dynamometers use a constant extension rate (200 mm/min, IIRW).

The Volatile Chemist - 12-6-2016 at 17:31

A quote from the website:
Quote:
Franklin and lots of other people have repaired their dishwashers with Sugru where it needs to withstand harsh detergents and high temperatures on a daily basis.
:)

It'd be useful, I guess, but isn't there some sort of silicone dip that would work for most chem apps anyways?

blogfast25 - 12-6-2016 at 17:54

Quote: Originally posted by The Volatile Chemist  
A quote from the website:

Quote:
Franklin and lots of other people have repaired their dishwashers with Sugru where it needs to withstand harsh detergents and high temperatures on a daily basis.
:)

It'd be useful, I guess, but isn't there some sort of silicone dip that would work for most chem apps anyways?


Assuming Franklin et al have been patching up any damaged EPDM based washing machine gaskets, I can assure you such a fix would be very temporary: Sugru is no match for highly developed, taylor-made EPDM formulations.

aga - 14-6-2016 at 07:13

The cured stuff does not like being submersed in conc sulphuric or nitric for a day or two, yet neither NaOH nor HCl seem to affect it :

IMG_2225.JPG - 141kB

The HNO3 treated sample has essentially retained it's original shape, although the colour has gone and the consistency is very much like putty.

blogfast25 - 14-6-2016 at 07:54

Quote: Originally posted by aga  
The cured stuff does not like being submersed in conc sulphuric or nitric for a day or two, yet neither NaOH nor HCl seem to affect it :



The HNO3 treated sample has essentially retained it's original shape, although the colour has gone and the consistency is very much like putty.


Although a visual inspection is fine, usually loss of mechanical properties is used as a measure of how chemically resistant a material is. So, TS and E@B after the treatment.

Try also immersing in a aliphatic solvent like kerosene. See if it absorbs it: weight gain (or loss).

aga - 14-6-2016 at 08:21

What's an aliphatic solvent, apart from kerosene (which i don't have) ?

Is Aliphatic the opposite of Aromatic ?

[Edited on 14-6-2016 by aga]

Crowfjord - 14-6-2016 at 09:11

Aliphatic refers to saturated alkanes (no double bonds, which would be olefinic). So, things like pentane, hexane, heptane, ligroin/petroleum ether, naphtha, and so on. If none of those are available, there's always gasoline/petrol.

[Edited on 14-6-2016 by Crowfjord]

aga - 14-6-2016 at 13:16

Thanks Crowfjord, and glad to see you again !

Petrol is now my aliphatic solvent of choice.

I have some of that.

deltaH - 15-6-2016 at 12:53

Petrol is not a good choice. Lighter fluid, like for zippo lighters, is a very aliphatic solvent.

aga - 15-6-2016 at 13:11

Pretty sure that Lighter fluid is still available, although it's composition (here) is unknown.

I'll get some and find out.

Edit:

Actually no, i'll not, these guys will :

sugrustrips.JPG - 105kB

They got slapped on the glass, rolled a bit with a steel rod, trimmed to ~10mm width, left to cure for 5 hours then scraped off the fume hood glass with a razor blade so they could cure freely overnight.

It took some acetone to get the remains off the glass - they're certainly sticky !

[Edited on 15-6-2016 by aga]

Oh dear.

I see that i just released an image of myself in the reflection, clearly showing the spok-like ears, oversized left eye and cranially-integrated imaging prosthetic.

That's not a stripey t-shirt, it's my gills.


[Edited on 15-6-2016 by aga]

deltaH - 15-6-2016 at 13:27

Lighter fluid is usually comprised of a strongly hydrotreated light naphtha, hence very aliphatic.

[Edited on 15-6-2016 by deltaH]

aga - 16-6-2016 at 06:52

Quote: Originally posted by blogfast25  
Also interesting: extend to say 50 % then stop extending and monitor stress. As a visco-elastic material its stress will reduce in time, aka stress relaxation.

stressrelax.gif - 7kB

Lika dat ?

Stretched a small piece to 50% then held it there.

Had to video the scales then step through it to capture the readings.

Stretchy-snappied some more bits :

sugrumpa.gif - 6kB
(WHOOPS : typo in the first image posted)

6 cured strips left.

What next ?


[Edited on 16-6-2016 by aga]

blogfast25 - 16-6-2016 at 08:33

@aga:

So that's a stress relaxation of about 12.5 %. Not bad, actually.

The other results still mystify me. The TS values are in agreement with Sugru's datasheet but the E@Bs fall well short (211 % advertised).

I wonder if the shape of the sample has something to do with that. Do the samples snap more or less at the middle (between the clamps) or at either side where you clamp them up?

If the latter is the case, that's why 'pro' tests use the dumbbell shape: that way stress is highest in he narrow section and it then breaks somewhere in that section.

Next, assuming you're up for it, clamp a sample at 50 % elongation for 24 h. Then release it and measure residual elongation 1 h after release. Perhaps compare with another rubbery material, for reference?

[Edited on 16-6-2016 by blogfast25]

NEMO-Chemistry - 16-6-2016 at 08:48

SWAN brand (yellow can) lighter fluid, is distilled (says something like extra distilled and clean) on the tin. Also says its napha on the tin. I know your not in UK but SWAN and brands like that with extra clean on the label should be napha and say so on them.

I used a couple of tins to try out as a extraction solvent, but gets pricey buying it like that if you need any volume.

aga - 16-6-2016 at 09:03

Quote: Originally posted by blogfast25  
Do the samples snap more or less at the middle (between the clamps) or at either side where you clamp them up?

Some did break where they are clamped and i also had some slip out of the clamps rather than break, so messed a bit with the clamping force.

The last entry on that table snapped exactly in the middle.

Does the thickness/width make any difference to the test ?

It seems like it should : thinner breaks sooner etc.

Edit:

A piece is now on the rack overnight, all stretchy-like.

[Edited on 16-6-2016 by aga]

blogfast25 - 16-6-2016 at 11:14

Quote: Originally posted by aga  


The last entry on that table snapped exactly in the middle.

Does the thickness/width make any difference to the test ?

It seems like it should : thinner breaks sooner etc.



'On paper', thickness has no influence on E@B. The sample is supposed to break when stress exceeds TS. The stress is of course the force divided by the cross section of the sample, which already accounts for the thickness.

For some projects we used to use different size dumb bells. The difference in observed E@B was always quite small.

Maybe the Sugru datasheet is telling porkies?

aga - 16-6-2016 at 11:32

The 'rack' is currently occupied, so i can't test the other bits just yet.

If my results with a home-made stretchy-snappy-o-meter come out seriously lower than their claimed elasticity, it should be no problem to just say that i did it wrong/the machine is crap/drunkards can't stretch/white men can't jump etc. etc.

That said, 65% E@B is a lot lower than 211%.

Nobody would care anyway.

Hmm. Perhaps the designers would.

Perhaps they could get their money back from the testing house that did it for them.

Calibration !

What are professional stretchy-snappy-o-meters calibrated with ?

blogfast25 - 16-6-2016 at 13:25

Quote: Originally posted by aga  

Nobody would care anyway.

Hmm. Perhaps the designers would.

Perhaps they could get their money back from the testing house that did it for them.

Calibration !

What are professional stretchy-snappy-o-meters calibrated with ?


The load cells are calibrated with standard weights, the extensometer (that measures elongation) with a good quality ruler.

I think I need to buy some Sugru myself. :) 75 % E@B is a really shockingly low value for what's being hyped/branded as a 'wonder material'...

[Edited on 16-6-2016 by blogfast25]

aga - 16-6-2016 at 13:39

It is possible that i just screwed it up, failed to properly tighten the screws on the machine i built, then failed to read a digital scale correctly, failed to turn the knob with any precision, and their Test Lab had MUCH better knobbing and screwing capabilities.

I'll email them and ask if we're wrong.

Edit:

These things never turn out well, but needs must ...

[Edited on 16-6-2016 by aga]

blogfast25 - 16-6-2016 at 16:02

Quote: Originally posted by aga  
It is possible that i just screwed it up, failed to properly tighten the screws on the machine i built, then failed to read a digital scale correctly, failed to turn the knob with any precision, and their Test Lab had MUCH better knobbing and screwing capabilities.



No. I deem it unlikely, actually. Your machine may be a little ad hoc and simple but there's no reason to believe it would underestimate the E@B values to such an extent (75 % compared to 211 % is a relative underestimate of 60 to 70 !!) Especially as the TS values seem in line with Sugru's specs.

I would only advise one more simple test: with an improvised dumbbell, cut with scissors from a bit of Sugru cured sheet. This is to eliminate those possible clamp effects.

General dumbell shape reminder (scale it to requirements):
http://www.ptli.com/testlopedia/subs/Tensile-rubber-sample.a...

aga - 17-6-2016 at 06:54

Overnight test :-

Start length: 15.47mm
Initial Force applied: 27.9 N (50% of max stretch)
Duration: 20 hours
Length afterwards: 17.16mm
Difference: 1.69mm

blogfast25 - 17-6-2016 at 07:43

Quote: Originally posted by aga  
Overnight test :-

Start length: 15.47mm
Initial Force applied: 27.9 N (50% of max stretch)
Duration: 20 hours
Length afterwards: 17.16mm
Difference: 1.69mm


A tension set of about 11 %, which is not bad at all.

The tension set is a qualitative measure of crosslink density. In plain English: a low value shows the sample has been properly cured (an uncured sample would have a tension set of about 100 %)

This also means that poor curing can be more or less excluded as the cause of the low E@B values.

Does this Sugru stuff smell of anything when it's curing?

[Edited on 17-6-2016 by blogfast25]

aga - 17-6-2016 at 09:02

Quote: Originally posted by blogfast25  
Does this Sugru stuff smell of anything when it's curing?

Yes. It has a particular smell which is not altogether unpleasant, yet certainly has an effect on these sinuses if sniffed hard.

The smell is not familiar, so no name springs to mind.

The best i can describe it is like a mix of an acetone/carbon tet-like solvent and burnt metal vapours (e.g. angle grinder meets steel).

No ammonia smell at all.

Today i stumbled across ICl (as in iodine monochloride) which is said to be useful for cleaving C-Si bonds.

Maybe making a bit of that and seeing how it affects the sugru material would be interesting.

The E@B issue probably isn't down to sample shape anymore, although a couple more packs have been opened and formed into the dumbell shapes, then left to cure overnight.

Edit:

As an afterthought one lump was balled up again and had a bit of damp pH paper stuffed into it to see if the pH of the solvent was measurable.

Came out the green of pH 8.

[Edited on 17-6-2016 by aga]

blogfast25 - 17-6-2016 at 09:59

@aga:

You're not getting any whiffs of vinegar? pH 8 would be in line with that.

Look forward to the dumbbells results.

Cleaving Si-C bonds? I don't think there are any in the backbone: silicone rubbers have a -O-Si-O-Si- backbone:

https://en.wikipedia.org/wiki/Silicone_rubber#Structure

aga - 17-6-2016 at 11:48

Well, if it's got any C in there, which it should have, and they get lopped off, it could be interesting.

Maybe makes it cross-link more, release some methyl groups which then react with excess ClI making a bit of methyl iodide or chloromethane ...

Best try a very small amount.

aga - 21-6-2016 at 07:14

Dumb-bell shapes are easier to work with than straight bits too.

More stretchy-snappy results:

dumb.JPG - 65kB brown.JPG - 64kB yellow.JPG - 64kB pink.JPG - 66kB results.gif - 7kB

Definitely not getting anywhere near 211% E@B.

blogfast25 - 21-6-2016 at 10:54

@aga:

I think that more or less settles it: even with dumbbells the E@B is well below a 100 %, far from the 211 % advertised.

Even allowing for differences in testing protocols (theirs is likely a very tight ASTM or ISO Standard) the found differences in E@B must be due an error on their part.

aga - 21-6-2016 at 11:06

Might be an error on the part of the testing house that actually tested it rather than the manufacturer.

I read on the website something about the current product being 'F10' which i assume means 'formulation #10' so there may have been confusion between formulations tested, or possibly they tested the un-cured material (!) which probably will go to 200%+, although the TS would be crappy.

Three weighed pieces of cured material are swimming under an aliphatic solvent (zippo lighter fluid) to see what happens.

1 sample left unopened.

Would you like the uncured portion tested for elongation ?

Not sure that Clamping would even be possible, although Shaping would be easy ;)

[Edited on 21-6-2016 by aga]

blogfast25 - 21-6-2016 at 11:25

Quote: Originally posted by aga  

Would you like the uncured elongation results ?

Not sure that Clamping would even be possible, although Shaping would be easy ;)


That requires a different testing protocol: uncured elastomers are high viscosity non-Newtonian liquids. So no.

The Zippo resistance should be interesting though.

aga - 21-6-2016 at 11:28

Duration ?

Soaking started ~2 hours ago.

blogfast25 - 21-6-2016 at 13:13

Quote: Originally posted by aga  
Duration ?

Soaking started ~2 hours ago.


About 3 days, I'd say.

aga - 21-6-2016 at 13:23

So, when 72 hours are up, does it need to be dried thoroughly, simply wipe it with kitchen towel, or do you just weigh it wet ?

Not trying to be pernickety here, just that i do not know what should be done to get the most accurate measurement possible in an amateur setting.

[Edited on 21-6-2016 by aga]

blogfast25 - 21-6-2016 at 16:43

Quote: Originally posted by aga  
So, when 72 hours are up, does it need to be dried thoroughly, simply wipe it with kitchen towel, or do you just weigh it wet ?

Not trying to be pernickety here, just that i do not know what should be done to get the most accurate measurement possible in an amateur setting.



By all means be 'pernickety', we're trying to do science here. :)

Wipe with kitchen towel to remove any superficial solvent clinging to the sample. Then weigh immediately. Reading will decrease a little in time as absorbed solvent evaporates slowly but that's OK.

Keep the unopened sample for a special occasion! :D

[Edited on 22-6-2016 by blogfast25]

Ask and ye shall receive !

aga - 23-6-2016 at 07:56

Quote: Originally posted by aga  
I'll email them and ask if we're wrong ...

These things never turn out well, but needs must ...

I was totally wrong to be so pessimistic !

Samuel from the Sugru people (FormFormForm Ltd) emailed back with very informed, helpful and positive comments, clearly having read this thread.

Personally i am really pleased that they have responded so positively. If only all customer service were anywhere near as good !

It is a refreshing change to encounter a manufacturer willing to take the time to discuss anything, let alone what may appear to be a challenge to their product's specs.

They very kindly supplied the exact measurements of their own dumb-bell test pattern, so a mould has been made to the same dimensions and the last bit of Sugru material has been used to make a more accurate test sample, which is curing now.

mould.JPG - 57kB

The aluminium sheet is 2mm thick, screwed to a nylon baseplate.
Centre portion is 12.5mm wide by 75mm long.

The Sugru was 'kneaded' for 20 seconds then forced into the mould, then rolled to the thickness of the aluminium with a wetted steel rod, so the result will be 2mm thick +/- curing shrinkage.

I just hope it won't stick like crazy to nylon.

Once cured, the middle section has to be trimmed down to 3.86mm wide to form the desired shape.

The Volatile Chemist - 23-6-2016 at 11:27

Huh, and I thought this stuff was from a crappy start-up. they may have something to them...curious to see how the stuff holds up.

aga - 23-6-2016 at 11:43

Quote: Originally posted by The Volatile Chemist  
Huh, and I thought this stuff was from a crappy start-up.

Why would they be assumed to be a 'crappy' start-up ?

Starting a business is a complicated and difficult thing to do, especially for a Manufacturer of a new product.

To be 'crappy' in any way would certainly mean failure, which equals lots of lost $.

As the Product works, and at least i bought some, and the customer service post-sale was, well, Superb, i can only assume that all the possible Planning was done years ago, eliminating any suggestion of 'crappiness'.

Anyone wanting to start a new business can U2U me their Business Plan and i'll go over the figures for them for free.

blogfast25 - 23-6-2016 at 11:49

The Sugru Saga! ;)

The Volatile Chemist - 23-6-2016 at 12:06

Quote: Originally posted by blogfast25  
The Sugru Saga! ;)

Quite the story, I gave a good portion of it a read. Good stuff

And Aga, I suppose you're right. I'd love to have a start-up, but in looking through the regulations and legalese and shite required for taxation and employees, I'd want to do it all myself, yet would go insane if I tried. It's quite the job..

aga - 23-6-2016 at 12:19

Hmm. Reading the 'story' there's a lot of Background unmentioned.

Rather a lot of 'useful connections' and a seriously large amount of $ is skipped over.

For someone with an 'idea' who says "I mean, I gave up chemistry in school!" to get to an air-curing formulation of two organo-silanes is a bit of a leap.

I checked the labels on all the bottles in my lab, and i don't seem to have any silane, so maybe if i mix up some stuff in a bucket of sand i might get lucky.

To go from 1 person to a staff of 10 requires a VAST amount of money, even for a short time.

To leap the Atlantic requires enough $100 bills to float the Titanic.

Maybe more of a Riches to Riches story.

Still, a nice material, and good on yer to whoever Actually formulated it.

aga - 23-6-2016 at 12:22

@TVC if you ever Do It, do it alone, do it smart, and do it well.

Staff are expensive in time, money and emotion.

Automate absolutely everything you can = Work Smarter.

Once perfected, the machines do most of your work, leaving plenty of drinking time :)

blogfast25 - 23-6-2016 at 12:51

Quote: Originally posted by aga  

For someone with an 'idea' who says "I mean, I gave up chemistry in school!" to get to an air-curing formulation of two organo-silanes is a bit of a leap.



No, not at all. Air-curing silicone caulks are thirteen in a dozen: it's what you use to seal sinks, showers and baths e.g. It's quite 'old' technology.

By her own story, she started mixing some of those with various powders and pigments/dyes for a Final Year project. It requires very little chemistry because the base polymers are off-the-shelf, the rest is mainly mixing.

See also the various DIY versions of Sugru.

It's a nice little material but highly hyped: it will never be anything like an engineering elastomer or a thermoplastic elastomer (these are huge markets). But hyped well, sold as a kind of sophisticated Bluetack in small amounts at high £/kg prices, Sugru is probably a small but viable business.


[Edited on 23-6-2016 by blogfast25]

aga - 23-6-2016 at 13:01

Quote: Originally posted by blogfast25  
Sugru is probably a small but viable business.

...which would not naturally attract dozens of serious investors.

A London wage would be about £2,000 a month.

10 staff.

£20,000 a month, just for staff, ignoring anything else.

1 year = almost a quarter of a million pounds in that year alone.

Still qualifies as 'small' as in Small to Medium Enterprise (SME) but not quite within most people's reach.

blogfast25 - 23-6-2016 at 13:36

Quote: Originally posted by aga  

Still qualifies as 'small' as in Small to Medium Enterprise (SME) but not quite within most people's reach.


How long is a piece of string? 10 is 10 x more than a self-employed person. But about 1700 x smaller than the last elastomer producer I worked for. Capacity about 200,000 mT/year.

Where are the 'dozens of serious investors'?

From their site:
Quote:
Nesta, the UK’s innovation think tank, awarded the Company a £35,000 Creative Pioneer grant to get off the ground.



[Edited on 23-6-2016 by blogfast25]

aga - 23-6-2016 at 13:43

Business 'science' is a lot easier than chemistry.

SME is well defined : http://ec.europa.eu/growth/smes/business-friendly-environmen...

Most reasonably sized busesses are SME's.

Bigger ones are better called Gargantuans.

aga - 24-6-2016 at 06:14

The soak-in-solvent test is done.

3x ~1.5g strips of cured material submersed in zippo lighter fluid for ~70 hours.

After day 1 more fluid had to be added to ensure submersion.

sugafter.JPG - 65kB

The middle green one is the un-treated control.

weightgain.gif - 5kB

aga - 24-6-2016 at 07:03

And finally ...

A 'proper' dumb-bell shape was made as close as possible to their spec and tested, giving TS=1.8MPa, E@B=36%.

The TS is pretty much spot-on, but the E@B is still miles off 211%.

lastsnap.JPG - 146kB

That was the last one, so no more samples to play with.

[Edited on 24-6-2016 by aga]

blogfast25 - 24-6-2016 at 08:05

That E@B is an exceedingly poor value for any type of rubber. A bit mystifying, actually... :o

Nice work with the dumbbells.

70 w% increase in Zippo is quite high too. Not really suited for oily environments then.


[Edited on 24-6-2016 by blogfast25]

aga - 24-6-2016 at 08:59

Might be an idea to check my maths.

E@B is elongation at breaking point right ?

If the starting length is 55.04mm,
length at snapping point is 74.86mm,
i get an elongation of 19.82mm = 36%

Their specs state "Strain-to-failure: 211%" so is that the same thing as E@B ?

blogfast25 - 24-6-2016 at 10:17

Quote: Originally posted by aga  
Might be an idea to check my maths.

E@B is elongation at breaking point right ?

If the starting length is 55.04mm,
length at snapping point is 74.86mm,
i get an elongation of 19.82mm = 36%

Their specs state "Strain-to-failure: 211%" so is that the same thing as E@B ?


Yup. It's all good. "Strain-to-failure: 211%" IS the same thing as E@B.

I can see from the pix with your dynamometer that the E@Bs you calculate are indeed correct.

If you've got a small piece left (even one you snapped before) verify it . manually: 211 % means you should be able to stretch it at least to approx. 3 x its original length, before it snaps.
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