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4. Corning and the First Silicones for High Temperature Insulation
Ahead to Silicone
6. (CH3)2SiCl2
Ahead to Silicone
7. Understanding of Polymers, Thermochemistry, and Kinetics
Chemical
Concepts
Let's begin to list the chemical concepts
you will reinforce in this silicone rubber unit:
| 4.
Silicon |
forms |
Reactive
bonds to halogens and hydrogen and stable bonds to carbon |
| 5.
Balanced chemical equations |
are essential |
for
understanding silicon chemistry |
Dr. Eugene Rochow extended Kipping's thinking
using microscopic analysis of potential chemical reactions.
Micro/Macro
and Symbolic
Representation
Chemistry uses macroscopic, large
scale observations to help describe and understand matter at the unseeable,
molecular level.
 |
And then
we represent both the microscopic and macroscopic with often complex symbolic
representation. |
Dr. Eugene Rochow extended Kipping's thinking
using microscopic analysis of potential chemical reactions. At the right
we see a scientist at his best. Rochow thinks on both the macroscopic and
molecular level at the same time. He needs a high-temperature insulation
- a macroscopic property, observable by all of us. In order to direct his
own work - to answer the question , "What shall I do next?" he thinks about
the specific atom-to-atom bonding that will achieve the desired results. |
|
Heat and Chemical Resistant
Silicone Rubber
5. Organic
Silicones at General Electric
The invention of practical
silicone resins occurred at General Electric. Silicones came from
a combination of patient thought and brilliant laboratory technique.
And they came from a willingness to be led by others' ideas.
In the late 1930's, Corning
chemists made samples of silicone materials that insulated critical electrical
devices at up to 180 degrees Celsius. But the insulators could not be manufactured
efficiently at a cost that was practical.
| They would
be impossibly difficult to make in high volume and be outlandishly costly.
But Corning made a decision to invite the people over at nearby General
Electric to drive over to look at samples of their new resin. |
 |
 |
The Corning scientists
at Corning,
NY and the General Electric scientists at Schenectady
still visit each other regularly. The relationship between the two
research groups has been strong ever since Corning developed the machinery
to begin automatic manufacture of glass globes for GE's light bulbs. |
So in 1938, Corning's
Dr. James Hyde invited scientists in GE's research group come over to Corning
for a presentation about Corning's new high temperature insulating materials,
the silicones. GE's Winton Patnode made the visit to Corning; he
listened to the Corning story and it confirmed some ideas of his own.
Dr. Patnode had believed that silicon containing compounds would
indeed provide the answer to the high-temperature insulation problem. He
drove back to Schenectady and sat down with a friend doing insulation research
at the General Electric laboratory, Dr. Eugene G. Rochow.
Let's look at what happened
next beginning with Dr. Rochow's internal monologue. Dr. Rochow was
trained as an inorganic chemist, a chemist whose experience with organic
chemistry - the chemistry of carbon compounds, was quite limited.
| Rochow's
Monologue:
"I was busy with several .
. . problems at the time, but kept thinking about Patnode's (ideas) and
Hyde's silicone. The questions and answers went like this.
(Q) What is really needed?
(A) A flexible inorganic
insulation that will stand at least 200 or 300 degrees Celsius in service.
(Q) What are the chances of
its being 100% inorganic
(A) Practically nil.
(Q) If we have to admit some
of the enemy (carbon-containing groups - editor) into the camp, what form
should it take?
(A) It should constitute an
absolute minimum of the whole and it should have no carbon-carbon bonds,
lest it end up as C-C-C-C-C conducting resins in the motor.
(Q) How should these organic
groups, so grudgingly admitted and only for the sake of flexibility, be
attached to the inorganic main framework of this imaginary new polymer?
(A) By direct carbon-metal
bonds, not through oxygen because they would always be hydrolyzable (react
with water - editor) under damp conditions.
(Q) What would be the best
metal for the backbone?
(A) Considering that we shall
be dealing with carbon-metal bonds, probably silicon, because its alkyls
such as (CH3)4Si
are thermally stable and do not react with water or
air in the 200-300degrees Celsius range."
From: Silicon
and Silicones, Eugene G. Rochow, Springer-Verlag, Berlin, 1987, p.65 |
Rochow's thoughts led to a single
structure. All his considerations led to a methyl silicone:
CH3
|
(-Si-O-)n
|
CH3
The decision to seek a methyl
silicone took Rochow in a different direction than Kipping had gone. But
Rochow recognized he would meet one serious problem with the methyl silicones.
They had never been made and he could find no guidance in the chemical
literature for how he would make them.
 |
And Eugene
Rochow said, "So what? Get busy and make it!" |
|
