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Back to Silicone 12. Quiz: Choosing
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Ahead to 15. Breast Augmentation
Implants
Chemical
Concepts:
Silicone
materials exhibit unique properties based on their
chemical structure. The bond enthalpies, (the
measure of bond strength) of silicon-oxygen and silicon
carbon bonds is quite high so the organic silicones tend
to be stable. And the configuration of the
silicones has the water-resistant hydrocarbon groups
arrayed along the outside of the chain of Si-O atoms.
Silicones act like hydrocarbon polymers like
polyethylene. Water does not "know" the
hydrophilic Si-O chain is even there.
| 14.
Si-O high bond energies |
lead
to |
heat
stability in silicones |
| 15.
Silicones' water-resistant molecular surface |
prevents |
cell
attachment and makes them seem inert. |
But in the grand scheme of
proliferating end-uses for silicones, one end
use, at first attractive and appealing, let loose
a tide of physical, emotional and legal
controversy that swamped the abilities of the
major silicone producers. One of them,
Dow-Corning, a company formed between Dow
Chemicals and Corning Glass, has chosen
bankruptcy in the controversy over the medical
effect of implant devices for breast
augmentations.
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Heat and Chemical
Resistant Silicone Rubber
13. Thousands of Useful Products
General
Electric's heat resistant silicone polymers had other
properties. The polymers:
 Were
inert to many chemical agents,
Could not be wet by water,
Resisted
the attack of oils and greases,
Could be made so pure that it
seemed they were inert as medical implants inside the
body.
These are materials with thousands of uses.
GE's Eugene Rochow wrote in 1987, "If silicone
resins for electrical equipment were its only output, the
silicone industry would only be one tenth of its present
size.
General Electric's scientists
helped developed major families of silicones.
Rubbery materials that could be
fabricated into tubing, hose, gaskets,
seals. These rubbers required some new
chemistry so they could be "cured" -
the process that converts a raw rubber compound
into a useful article. GE's engineers
coated these rubbers onto glass fibers to make
the electrical insulating tapes they initially
sought.
Resins for hard coatings, films and
paints.
New chemistry for RTV's - (Room
Temperature Vulcanizable) products. These
are the familiar tubes of sealant that we squeeze
in place and allow to cure by the action of the
moisture in the air.
Fluids that were heat and chemically
stable. These fluids were extraordinary
lubricants, they would not be attacked by water
so they became water repellants. And in the
early 1960's, physicians began to implant
silicone fluid filled sacs for breast augmentation.
GE's Dr. Patnode observed that the
silanes themselves, such as (CH3)2SiCl2 (9) would make
cloth and paper water resistant. Water
would not be absorbed by treated articles - the
water just beaded up on the surface.
Dozens of silane materials are used today for
protection from water.
15 uses for silicone polymers of all
types developed since 1940:
ELECTRICAL/
ELECTRONICS
Silicone
impregnated electrical insulating tapes, silicone
rubber, adhesives, sealants, elastoplastic resins
for coatings of circuit boards, compounds for
potting and protecting semiconductor devices,
dielectric compounds, high-purity coatings,
varnishes, resins, specialty lubricants, optical
fiber coatings and fiber optic cable filler, and
semiconductor-grade silicon and silicon-source
chemicals.
|
AEROSPACE
Space
suit fabrics, boots, windshield and canopy gasket
sealants, rubber tooling for radome fabrication,
optical interlayer laminates, abrasion-resistant
coatings, adhesives, seals and gaskets, and
tooling materials.
|
 CONSTRUCTION
Construction
adhesive /sealants, glazing adhesive/sealants and
elastomers, silicone/polyurethane foam roof
coatings, firestop foams and sealants,
architectural coatings and water repellents.
Concrete pavement joint sealants. Treatments for
new construction and renovation
applications.
|
 FOOD
PROCESSING
Silicone
antifoams, bakeware coatings; processing aids for
food processing applications.
|
 AUTOMOTIVE
Heat,
oil and fuel-resistant silicone rubbers for
molding into a variety of durable parts; one or
two part sealants and adhesives, specialty
lubricants and materials for noise, vibration,
harshness and thermal management, automotive
polishes.
|
 INDUSTRIAL MAINTENANCE AND
PRODUCTION
Silicone
elastomers, adhesives, sealants, dielectric
compounds, varnishes, multi-purpose
silicone fluids, antifoams, release agents,
surfactants, maintenance lubricants, elastomers
and greases.
|
 MEDICAL
PRODUCTS
Medical-grade
tubing, adhesives, defoamers and fluids.
|
 TEXTILES
AND LEATHER
Waterproofing
treatments and fiber chemicals.
|
 CONSUMER PRODUCTS
Silicone
adhesives, sealants and caulks for home
improvement and renovation by do-it-yourselves.
|
 PAINTS
AND COATINGS
Silicone
additives for high-performance paints, enamels,
finishes and abrasion resistant coatings for
plastics. Silicone rubber compounds for
temperature and chemical resistant printing
equipment components.
|
 PLASTICS
Mold
release additives, catalyst modifiers, and
chemicals for high-performance plastics
applications.
|
 PRESSURE-SENSITIVE ADHESIVES
Release
coatings for backings on tapes, labels, stamps,
stickers, decals and food packaging;
pressure-sensitive adhesives.
|
 PERSONAL
AND HOUSEHOLD CARE
Surfactants,
emulsions, fluids and powder treatments are
important ingredients in skin and suntan lotions,
anti-perspirants, hair care products, shaving
creams, cosmetics, starches, fabric treatments,
laundry products and more.
|
 PHARMACEUTICALS
Medical-grade
fluids, emulsions, antifoams, adhesives and
silicone rubber tubing.
|
 MEDICAL
IMPLANTS
Temporomandibular
Joint (jaw) implants; Small Joint Orthopedic
(finger) implants; Large Joint Products (hip,
knee, elbow) implants; Long term implantable
contraceptives; Silicone fluids for injection and
certain
custom silicone implant products.
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