Polycarbonate glue?

[Martin Brown]

Food processor plastic bowl seems to be polycarbonate and took a
sufficiently hard thump on the hard kitchen floor to put a vertical 4cm
crack in the outer case near to the handle. It will doubtless get worse
if not repaired. Any suggestions for a suitable thin glue for
polycarbonate that will wick into the crack and prevent it from running.

Would it make sense to drill into the end of the crack for stress relief
or be more likely to make it worse?

Ideal glue would be food safe (so epoxy which might work isn't ideal).

ISTR that petrol or ether might be good solvents for polycarbonate but I
have a feeling they make it go brittle too which would be no use in a
food processor where the mechanical strength is important.

Any suggestions for the best glue to use here?

--
Regards,
Martin Brown

[MrCheerful]

Methylene chloride fuses polycarbonate. You might find that the glue
for solvent weld waste pipe would do.

[Capitol]

For fine cracks I always use superglue which has very good wixking
properties. I find it will also fill slightly wider cracks with a few
more coats. Easy to clean up with a scalpel.

[Thomas Prufer]

On Sun, 4 Dec 2016 10:03:49 +0000, Martin Brown
<|||newspam|||@nezumi.demon.co.uk> wrote:

>Any suggestions for the best glue to use here?

UHU allplast -- a solvent weld glue.

Thomas Prufer

[MrCheerful]

and contains cyanide.

[Bob Eager]

And is not toxic, excelt perhaps when inhaled while applying it.



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[MrCheerful]

On 04/12/2016 11:31, Bob Eager wrote:
> On Sun, 04 Dec 2016 11:07:07 +0000, MrCheerful wrote:
>
>> On 04/12/2016 10:22, Capitol wrote:
>>> Martin Brown wrote:
>>>> Food processor plastic bowl seems to be polycarbonate and took a
>>>> sufficiently hard thump on the hard kitchen floor to put a vertical
>>>> 4cm crack in the outer case near to the handle. It will doubtless get
>>>> worse if not repaired. Any suggestions for a suitable thin glue for
>>>> polycarbonate that will wick into the crack and prevent it from
>>>> running.
>>>>
>>>> Would it make sense to drill into the end of the crack for stress
>>>> relief or be more likely to make it worse?
>>>>
>>>> Ideal glue would be food safe (so epoxy which might work isn't ideal).
>>>>
>>>> ISTR that petrol or ether might be good solvents for polycarbonate but
>>>> I have a feeling they make it go brittle too which would be no use in
>>>> a food processor where the mechanical strength is important.
>>>>
>>>> Any suggestions for the best glue to use here?
>>>>
>>>>
>>> For fine cracks I always use superglue which has very good wixking
>>> properties. I find it will also fill slightly wider cracks with a few
>>> more coats. Easy to clean up with a scalpel.
>>
>> and contains cyanide.
>
> And is not toxic, excelt perhaps when inhaled while applying it.
>
>
>

What is really unpleasant is the fumes if it is heated, I did that
accidentally while using a belt sander.

[Syd Rumpo]

On 04/12/2016 10:03, Martin Brown wrote:

Whatever glue you use, duct tape of some variety on the outside is good
if there's enough 'flat' space around the crack.

Cheers
--
Syd

[Andy Burns]

Martin Brown wrote:

> Food processor plastic bowl seems to be polycarbonate and took a
> sufficiently hard thump on the hard kitchen floor to put a vertical 4cm
> crack in the outer case near to the handle.

I've not tried it, but ... friction welding?

<http://www.frantone.com/designwritings/design_writings4.html#welder>

[Frank]

Looking through thread, that is a good suggestion as area of crack will
probably remain the weakest of the part. I've repaired cracks in
plastic areas where most stress occurs by gluing nylon screen over the
crack.

I'd use the solvent based glues for polycarbonate and not worry about
toxicity of any glue used as area is small and toxic materials are part
of the polymer.

If the crack can be slightly widened it will allow better contact with
glue or solvent, then resealed to complete gluing.

[unk]

Polycarbonate does not crack.

It's likely acrylic or styrene. MEK for acrylic, some other solvent-
based glue for styrene.

[The Natural Philosopher]

NO, contains cyanoacrylate.


--
"The great thing about Glasgow is that if there's a nuclear attack it'll
look exactly the same afterwards."

Billy Connolly

[The Natural Philosopher]

Oh yes, fumes are instant asthma for me, whether in use, or when sanding.

not QUITE as bad as aluminium flux though. That is REALLY nasty

[Poutnik]

Dne 04/12/2016 v 12:07 MrCheerful napsal(a):

Bound cyanogroup is not cyanide.
Its pure form is used even in surgery.

--
Poutnik ( The Pilgrim, Der Wanderer )

A wise man guards words he says,
as they say about him more,
than he says about the subject.

[newshound]

I was quite impressed by that idea. There's impressive video out there
of TWI's friction stir welding process which, IIRC, was used to make
very neat looking butt joints for space shuttle fuel tanks (and loads of
other stuff).

[Harry Bloomfield]

newshound wrote :

Me too, I have not come across that method before..

[Andy Burns]

Harry Bloomfield wrote:

> newshound wrote :

>
>> Andy Burns wrote:
>>
>>> <http://www.frantone.com/designwritings/design_writings4.html#welder>
>>
>> I was quite impressed by that idea.
>

> Me too, I have not come across that method before..

I think a colleague mentioned getting a plastic welder a few weeks ago,
but he hasn't mentioned any success or failure with it since ... I'll ask.

I should think a suitable plastic rod in a dremel would be all you'd need.

[dlzc]

I think all you need is a "straight pin". You do not add material, you "simply" use localized friction of the rotating pin to melt the existing plastic.

David A. Smith

[Martin Brown]

Tell that to my rear light cluster.

It does when provoked sufficiently. It is a short hairline crack along a
weak line near where the handle joins the body of the mixer bowl.

It will doubtless get worse if not repaired.
>

> It's likely acrylic or styrene. MEK for acrylic, some other solvent-
> based glue for styrene.
>

I'll test it but I want to avoid the mess that I got by using acrylic
solvent glue on my definitely polycarbonate rear light cluster.

Acrylic would probably just about stand up to the duty but I doubt if
polystyrene would (and the latter tends to yellow a lot with age).

--
Regards,
Martin Brown

[Martin Brown]

Cyanoacrylate. (Different functional group CNO vs CN).
More significantly it doesn't get on that well with hot water.

It was originally intended for battlefield wound repairs on flesh and it
is used as an alternative to sutures in hospitals for smaller wounds and
in places where they would prefer to avoid scarring from stitches.

--
Regards,
Martin Brown

[Martin Brown]

That sounds a possibility. What I want to avoid is causing any stress
corrosion cracking in a polycarbonate vessel that is basically exposed
to high shear conditions and has plenty of surface microscratches.

Petrol for instance is very bad for polycarbonate.

--
Regards,
Martin Brown

[rick]

On 04/12/2016 21:06, Poutnik wrote:
> Dne 04/12/2016 v 12:07 MrCheerful napsal(a):
>> On 04/12/2016 10:22, Capitol wrote:
>>>
>>> For fine cracks I always use superglue which has very good wixking
>>> properties. I find it will also fill slightly wider cracks with a few
>>> more coats. Easy to clean up with a scalpel.
>>
>> and contains cyanide.
>
> Bound cyanogroup is not cyanide.
> Its pure form is used even in surgery.
>

correct
original major use of superglue was wound closure in Vietnam war

[dlzc]

I find links on the internet, on using the high speed Dremels to act as spin welders. No filler required. No stress-relieving crack-stopping holes required.

David A. Smith

[Norm X]

> and contains cyanide.

Not true. Sodium cyanide contains the cyanide anion, but cyanoacrylates are
organic molecules that contain the cyano moiety or functional group. Big
difference. You will die if you eat sodium cyanide but water in saliva will
hasten the polymerization of cyanoacrylate. I have see medical publications
where types of superglue were assessed as surgical glues for internal use.
In harsh circumstances it has been sprayed onto an open wounds, in a dilute
solution.

[Poutnik]

Dne 24/12/2016 v 05:53 Norm X napsal(a):

They differ in the alkyllengths.
Methyl or ethyl esters are used for technical glues,
n-butyl or 2-oktyl esters in veterinary or human medicine.

https://en.wikipedia.org/wiki/Cyanoacrylate