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How Does Glue Work?
Name: Jackson
Status: student
Grade: 6-8
Location: NY
Question
How can glue stick things together?
Replies:
Jackson,
There are many variants of glue and there are some slight differences in the
details of how they work, so I will just talk about how glues work in general.
The first requirement is that glues must be able to creep or flow into the
crevices of the two objects that are being attached together. At the microscopic
level, even surfaces that appear smooth will, in general, be very rough - full of
mountains and valleys and crevices. The glue has to be able to seep into these
crevices. The second requirement is that the glue must be able to change its
molecular structure so that it changes from a fluid to a solid - it must harden.
There are many ways this can be achieved. Reaction with atmospheric oxygen,
addition of a cross-linker, thermosetting (hardening due to an application of
heat), etc. All of these processes have the result of making the glue harden or
cure.
So, what we can imagine then, is that the glue, as a fluid will seep into the
microscopic cracks and crevices of the two objects that are being attached
together. Then, through some predetermined mechanism, the glue hardens or cures.
The result is that the parts of the glue that have seeped into the objects at the
microscopic level are like anchors and hold onto the objects. The hardening
prevents those anchors from getting dislodged and also makes the glue a hard
object to break.
Greg (Roberto Gregorius)
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Update: February 2012
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