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Heat and Chemical Resistant Silicone Rubber
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.
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:
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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.
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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.
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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.
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Silicone antifoams, bakeware coatings; processing aids for food processing applications.
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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.
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Medical-grade tubing, adhesives, defoamers and fluids.
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TEXTILES AND LEATHER
Waterproofing treatments and fiber chemicals.
Silicone adhesives, sealants and caulks for home improvement and renovation by do-it-yourselves.
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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.
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Mold release additives, catalyst modifiers, and chemicals for high-performance plastics applications.
Release coatings for backings on tapes, labels, stamps, stickers, decals and food packaging; pressure-sensitive adhesives.
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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.
Medical-grade fluids, emulsions, antifoams, adhesives and silicone rubber tubing.
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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.
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.