What is the chemical force that makes common household glues work

Very few are solvents such as the pipe-fitting "glues" which actually melt
(weld) the plastic together.

Most are some kind of "bonding", where some glues are strong themselves,
like Elmers Glue but while others are extremely weak in and of themelves,
like Cyanacrylate crazy glue - but what kind of bonding is glue?

Looking at the Shoe Goo MSDS, it's toluene based but that's all I can get
out of the MSDS. The toluene is the solvent which seems to vaporize,
leaving the "glue" behind mechanically wedged into all the molecular
crevices. http://www.bild.me/bild.php?file=6713513goop02.jpg

I know about covalent and ionic bonding and the nuclear strong and weak
forces, but common household glue doesn't seem to be any of those forces.

Common household glues seem to be some kind of strange "mechanical"
molecular cantilevered arm that "solidifies" and somehow mechanically holds
things together.

Do any chemists out there know what "force" is what holds most common glues
to their substrates?

I call it the "velcro force" because it's none of the common forces.
But what is it really?

There are a lot of forces at work but mostly chemical, both covalent and
ionic.

Mechanical is also important as glue might penetrate when it is liquid.

The mechanical properties of the glue are also important particularly
when bonding materials with considerably different mechanical properties.

Not a simple subject and I worked in the area in R&D for several years.

On 9/17/2017 3:21 PM, Mad Roger wrote:
What is the chemical force that makes common household glues work

Very few are solvents such as the pipe-fitting "glues" which actually melt
(weld) the plastic together.

Most are some kind of "bonding", where some glues are strong themselves,
like Elmers Glue but while others are extremely weak in and of themelves,
like Cyanacrylate crazy glue - but what kind of bonding is glue?

Looking at the Shoe Goo MSDS, it's toluene based but that's all I can get
out of the MSDS. The toluene is the solvent which seems to vaporize,
leaving the "glue" behind mechanically wedged into all the molecular
crevices. http://www.bild.me/bild.php?file=6713513goop02.jpg

I know about covalent and ionic bonding and the nuclear strong and weak
forces, but common household glue doesn't seem to be any of those forces.

Common household glues seem to be some kind of strange "mechanical"
molecular cantilevered arm that "solidifies" and somehow mechanically holds
things together.

Do any chemists out there know what "force" is what holds most common glues
to their substrates?

I call it the "velcro force" because it's none of the common forces.
But what is it really?

On Sun, 17 Sep 2017 16:14:09 -0400,
Frank wrote:

There are a lot of forces at work but mostly chemical, both covalent and
ionic.

Mechanical is also important as glue might penetrate when it is liquid.

The mechanical properties of the glue are also important particularly
when bonding materials with considerably different mechanical properties.

Not a simple subject and I worked in the area in R&D for several years.

Let's take the three most common types of household glue first:

1. Elmer's Glue (for example, wood to wood or paper to wood)
2. Crazy Glue (for example, plastic to plastic or steel to steel)
3. Shoe Goo (for example cloth to leather or rubber to cloth)

There's just no way that these three glues are "ionic" bonding with the
wood, plastic, or cloth respectively. Just no way. There is no "outer
layer" of electrons being shared in these cases.

Likewise with covalent bonding. It's just not happening.

I can't explain why though - but it's just not that type of bonding that is
going on. What type of bonding "is" going on, I don't know though.

I suspect nobody knows, but that's why I asked - which is to find someone
who knows what kind of bonding force is happening when two items are glued
together.

In article , says...

There's just no way that these three glues are "ionic" bonding with
the
wood, plastic, or cloth respectively. Just no way. There is no "outer
layer" of electrons being shared in these cases.

Buit I thought that every atom has an "outer layer" of electrons. (Well
maybe hydrogen's single electron is a degenerate "layer"!)

But I agree if "ionic" means electrostatic (like Na and Cl in salt) it
seems unlikely...

Mike.

On Sun, 17 Sep 2017 22:42:35 +0100,
Mike Coon wrote:

Buit I thought that every atom has an "outer layer" of electrons. (Well
maybe hydrogen's single electron is a degenerate "layer"!)

But I agree if "ionic" means electrostatic (like Na and Cl in salt) it
seems unlikely...

Mike.

Hi Mike,
I thank you for your opinion where I realize the extreme hazards of
responding on something that, most likely, none of us actually know the
answer to (least of all me).

Like you, I can't imagine that ionic bonding is going on here, although I
will readily admit I only have the chemistry training that everyone has,
which is, for ionic bonding, classically portrayed by the metal sodium and
the non-metal chlorine.

This bonding is an electrostatic force between oppositely charged ions,
anions and cations if you will, where the requirement is that both
compounds be ionic.

Taking our three common household glues:
1. Elmers (paper to wood)
2. Crazy (plastic to plastic)
3. Goop (rubber to leather)

I can't imagine that any of those materials are ionic, whether they be
paper, wood, plastic, rubber, or leather.

Can you?

If it's not ionic (which I can't imagine that it is), then we have covalent
bonding, which is a more complex sharing of electrons between atoms.

How is covalent bonding going on with plastic to plastic cyanacrylate
(crazy glue, Eastman Kodak 910) stuff?

The whole purpose of sharing electrons is to become more stable where, in
the case of glueing two things together, stability isn't what's happening.

For example, when I glue rubber to leather, stability of either the rubber
or the leather isn't the issue for the molecules. And yet, they're stuck
together so "some" kind of force must exist.

But what is that force of glue?

Clearly there "is" a bonding force.
But what is that bonding force?

On Sunday, September 17, 2017 at 2:25:42 PM UTC-7, Mad Roger wrote:
On Sun, 17 Sep 2017 16:14:09 -0400,
Frank wrote:
[about glue]

There are a lot of forces at work but mostly chemical, both covalent and
ionic.

Mechanical is also important as glue might penetrate when it is liquid.

There's just no way that these three glues are "ionic" bonding with the
wood, plastic, or cloth respectively. Just no way. There is no "outer
layer" of electrons being shared in these cases.

Likewise with covalent bonding. It's just not happening.

Oh, it's happening. The SURFACES of wood, plastic, cloth have material-air interfaces,
with some kind of loose chemical links (that would hold the material together, if you hadn't
run out of material when you got to the surface...) which is loosely holding on to
(maybe) oxygen or another interface layer of random stuff.

The glue first has to come into closer contact than that oxygen molecule, i.e.
it has to wet the surface and displace the O2. It has to flow into contact,
and either repel or dissolve the contaminants already present. Afterward,
it has to solidify into something with tensile strength, or shear strength, enough
to transfer force through the glue to the surface it bonds to.

Something like tin/lead solder joining metsls is EXACTLY covalent (metallic) bonding,
but with more complex materials, there's just a lot of different kinds of bonds
involved, Good glues, like soap, have hydrophobic and hydrophilic and all sorts
of bondable molecular sites, but unlike soap, they also harden or stiffen after some
time due to cooling, chemical restructuring, loss of solvent (vehicle).

On 9/17/2017 5:25 PM, Mad Roger wrote:
On Sun, 17 Sep 2017 16:14:09 -0400,
Frank wrote:

There are a lot of forces at work but mostly chemical, both covalent and
ionic.

Mechanical is also important as glue might penetrate when it is liquid.

The mechanical properties of the glue are also important particularly
when bonding materials with considerably different mechanical properties.

Not a simple subject and I worked in the area in R&D for several years.

Let's take the three most common types of household glue first:

1. Elmer's Glue (for example, wood to wood or paper to wood)
2. Crazy Glue (for example, plastic to plastic or steel to steel)
3. Shoe Goo (for example cloth to leather or rubber to cloth)

There's just no way that these three glues are "ionic" bonding with the
wood, plastic, or cloth respectively. Just no way. There is no "outer
layer" of electrons being shared in these cases.

Likewise with covalent bonding. It's just not happening.

I can't explain why though - but it's just not that type of bonding that is
going on. What type of bonding "is" going on, I don't know though.

I suspect nobody knows, but that's why I asked - which is to find someone
who knows what kind of bonding force is happening when two items are glued
together.


None of these form bonds except maybe weak hydrogen bonds with the
hydroxyls in wood and the glue. Makes it sort of a solvent situation
where the glue penetrates the wood fibers, just like when you dye cotton
and when dry is insoluble.

The other glues are in solvents and there is a little of like dissolves
like going on allowing the glues to penetrate except for the metals.
Metals often have oxide surfaces and there may be chemical interaction.

Shoe Goo is more of an adhesive with, again, like chemical contact to
like with glue to rubber.

My experience was mainly with epoxies and Kevlar adhesion to rubber and
plastics, even cement. All of these were chemical bonds.

Mad Roger wrote:


Most are some kind of "bonding", where some glues are strong themselves,
like Elmers Glue but while others are extremely weak in and of themelves,
like Cyanacrylate crazy glue


** CA glues are not weak of themselves.

The material sets harder than most glues, like contact adhesive or rubber/silicone glue.

Beside fast curing, the big advantage of CA glue is how it whets and penetrates into small gaps and pores in a materials before setting.

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


...... Phil

The Troll is back. Please don't feed the troll.

On 18/09/2017 7:34 PM, wrote:
The Troll is back. Please don't feed the troll.


So **** off then !!

On 18/09/2017 11:30 AM, Phil Allison wrote:
Mad Roger wrote:


Most are some kind of "bonding", where some glues are strong themselves,
like Elmers Glue but while others are extremely weak in and of themelves,
like Cyanacrylate crazy glue


** CA glues are not weak of themselves.

The material sets harder than most glues, like contact adhesive or rubber/silicone glue.

Beside fast curing, the big advantage of CA glue is how it whets and penetrates into small gaps and pores in a materials before setting.

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


**GOOD QUALITY CA glue is an excellent product for a variety of uses.
This is the stuff I've been using:

http://www.pascofix.com/

Of particular interest is this stuff (Pascofill):

http://www.pascofix.com/pasco-fix-instructions/

It allows for the building of fillets, thus making VERY strong joints,
when only small surface area is available. Since the Pascofix glue ran
out, I switched to Loctite, which I find excellent.



--
Trevor Wilson
www.rageaudio.com.au