Seal Dynamics offers the following plastic gasket materials:

Teflon® (PTFE)
An extremely low coefficient of friction makes Polytetrafluoroethylene the ideal choice for gasket materials where surface wear might otherwise be a problem. PTFE also exhibits a useful service life from below-100ºF, to temperatures of over 500ºF. Its resistance to solvents is also excellent throughout a wide range of temperatures. Its low dielectric constant and electrical resistance also remain constant throughout this range.

Polyethylene
This plastic gasket material came to the fore during the World War II years, first as an underwater cable coating, then as a critical insulating material for such vital military applications as radar cable. It was not until the end of the war that the plastic was taken off allocation and freed for consumer use. From that point on, its rise in popularity for both consumer and industrial uses was so spectacular that polyethylene became the first plastic in the U.S. to sell more than 1 billion pounds a year. Today, it is still the largest volume plastic in the United States; in fact, it is the largest in the world.

Applications for polyethylenes are many and varied, including: packaging films; trash, garment, grocery and shopping bags; molded housewares; toys; containers; pipe; drums; gasoline tanks; coatings and many others. Polyethylenes are thermoplastic resins obtained by polymerizing the gas ethylene [C2H4]. Low molecular weight polymers of ethylene are fluids used as lubricants; medium weight polymers are waxes miscible with paraffin; and the high molecular weight polymers (i.e., over 6000) are the materials used in the plastics industry.

Polymers with densities ranging from about .910 to .925 are called low density; those of densities from .926 to .940 are called medium density; and those from .941 to .965 and over are called high density. The low-density types are polymerized at very high pressures and temperatures, and the high density types at relatively low temperatures and pressures. A relatively new type called linear low density polyethylene is manufactured through a variety of processes: gas phase, solution, slurry, or high pressure conversion. A high efficiency catalyst system aids in the polymerization of ethylene and allows for lower temperatures and pressures than those required in making conventional low density polyethylene. Copolymers of ethylene with vinyl acetate, ethyl acrylate, and acrylic acid are commercially important.

Nylon
The nylon fiber industry was born in 1939 when 64 million pairs of nylon stockings were sold and to this day, most people still associate nylon with fibers. However, in the 1940s and 1950s work continued on developing nylon compounds that could be molded and extruded or otherwise processed like plastics. Typical applications for nylons are in automotive parts, electrical/electronic uses, and packaging.

Seal and Plastic Gasket Materials
Nylon is a generic name for a family of long-chain polyamide engineering thermoplastic gasket materials which have recurring amide groups [-CO-NH-] as an integral part of the main polymer chain. Nylons are synthesized from intermediates such as dicarboxylic acids, diamines, amino acids and lactams, and are identified by numbers denoting the number of carbon atoms in the polymer chain derived from specific constituents, those from the diamine being given first. The second number, if used, denotes the number of carbon atoms derived from a diacid. Commercial nylons are as follows: nylon 4 (polypyrrolidone)-a polymer of 2-pyrrolidone [CH2CH2CH2C(O)NH]; nylon 6 (polycaprolactam)-made by the polycondensation of caprolactam [CH2(CH2)4NHCO]; nylon 6/6-made by condensing hexamethylenediamine [H2N(CH2)6NH2] with adipic acid [COOH(CH2)4COOH]; nylon 6/10-made by condensing hexamethylenediamine with sebacic acid[COOH(CH2)8COOH]; nylon 6/12-made from hexamethylenediamine and a 12-carbon dibasic acid; nylon 11-produced by polycondensation of the monomer 11-amino-undecanoic acid [NH2CH2(CH2)9COOH]; nylon 12-made by the polymerization of laurolactam [CH2(CH2]10CO)or cyclododecalactam, with 11 methylene units between the linking -NH-CO- groups in the polymer chain.

Phenolic
These thermosetting resins are credited with being the first commercialized wholly synthetic polymer or plastic, and the second major plastic (the first being cellulose nitrate http://www.plasticsindustry.org/industry/defs.htm). The basic raw materials are formaldehyde [HCHO] and phenol [C6H5OH], although almost any reactive phenol or aldehyde can be used.

The phenols used commercially are phenol, cresols [CH3C6H4OH], xylenols [(CH3)2C6H3OH], p-t-butylphenol [C4H9C6H4OH], p-phenylphenol [C6H5C6H4OH], bisphenols [(C6H4OH)2], and resorcinol [C6H4(OH)2]. The aldehydes used are formaldehyde and furfural [C4H3OCHO]. In the uncured and semi-cured condition, phenolic resins are used as adhesives, casting resins, potting compounds, and laminating resins. As molding powders, phenolic resins can be found in electrical uses. As gasket materials, they are used in such applications as: automotive distributor caps, fuse blocks and connectors and appliance handles, knobs and bases. Phenolic is the most popular binder for holding the various plies of wood together in plywood.

If you would like more information about Seal Dynamics plastic gasket materials, please feel free to give us a call for more information.