Properties of Polymers

Select a material to jump to specific discussions.

CTFE

Chlorotrifluoroethylene, is the generic name for the material produced as Kel-F^® and as Aclar^®. It is very resistant to all chemicals except THF and some halogenated solvents, and is resistant to all inorganic corrosive liquids, including oxidizing acids. CTFE can be used at temperatures up to 100°C. Swells in ketones.

EPDM

Ethylene Propylene Diene Monomer. Ethylene-propylene synthetic rubbers offer excellent resistance to heat, oxidation, ozone, and weather aging due to their stable, saturated polymer backbone structure. As non-polar elastomers, they have good electrical resistivity, as well as resistance to polar solvents, such as water, acids, alkalies, phosphate esters, and many ketones and alcohols.

ETFE

Ethyltrifluoroethylene is the generic name for the material such as Tefzel^®. A fluoropolymer used for sealing surfaces, it is resistant to most chemical attack; however, some chlorinated chemicals will cause a physical swelling of ETFE tubing.

FEP

Fluorinated ethylene propylene is another member of the fluorocarbon family with similar chemical properties. It is generally more rigid than PTFE, with somewhat increased tensile strength. It is typically more transparent than PTFE, slightly less porous, and less permeable to oxygen. FEP is not as subject to compressive creep at room temperature as PTFE, and because of its slightly higher coefficient of friction is easier to retain in a compression fitting.

FFKM (Perfluorinated rubber)

FFKM is a Perfluoroelastomer, the class of materials that includes Kalrez®. It is chemically resistant to polar solvents, organic solvents, inorganic and organic acids and bases, fuels, oils, lubricants, inorganic salts, aldehydes, metal halogen compounds, chlorine, sodium hydroxide, aromatics, alcohols, steam, and strong oxidizing agents. The normal temperature service rance is -40°C to 315°C and up to 343°C in intermittent service.

PEEK

Considered relatively inert and biocompatible, poly-etheretherketone tubing can withstand temperatures up to 100°C. Under the right circumstances, .005” - .020” ID tubing can be used up to 5000 psi for a limited time, and 0.030” to 3000 psi. Larger IDs are typically good to 500 psi. These limits will be substantially reduced at elevated temperatures and in contact with some solvents or acids.

Its mechanical properties allow PEEK to be used instead of stainless in many situations and in some environments where stainless would be too reactive. However, PEEK can be somewhat absorptive of solvents and analytes, notably methylene chloride, DMSO, THF, and high concentrations of sulfuric and nitric acid. This tubing is highly prone to ”kinking”, or sealing off, if held in a sharp bend over time.

PFA

Perfluoroalkoxy is a fluorocarbon with chemical and mechanical properties similar to FEP. More rigid than either PTFE or FEP. Commonly used for injection molded parts.

For Cheminert fittings and Valco ferrules,

PPS

Polyphenylene sulphide is the generic name for the material produced as Fortron^®, Ryton^®, and others. It is very resistant to all solvents, acids, and bases.

For Cheminert valve stators.

PTFE

Polytetrafluoroethylene is the generic name for the class of materials such as Teflon^®. It offers superior chemical resistance but is limited in pressure and temperature capabilities. Because it’s so easy to handle, it is often used in low pressure situations where stainless steel might cause adsorption. PTFE tubing is relatively porous, and compounds of low molecular weight can diffuse through the tubing wall.

For Valco ferrules, and tubing.

Polyacetal

Polyacetal or Polyoxymethylene (POM) is the generic name for the material produced as Delrin®. It is an engineering polymer with high mechanical strength and rigidity, excellent dimensional stability, and excellent resistance to moisture and solvents. It has a wide useful temperature range in air of -50° to +90°C. It is not suitable for use with acids, alkalis, and oxidizing agents, and has limited resistance to dichloromethane and methyl ethyl ketone.

Polyamide

Polyamide is a thermoplastic polymer also known as Nylon. Nylon has very good physical properties, but moisture can have a significant effect. It exhibits very good heat resistance and excellent chemical and wear resistance.

Polyethylene

Polyethylene is a semi-crystalline material with excellent chemical resistance and good fatigue and wear resistance. Polyethylenes provide good resistance to organic solvents and staining, and have low moisture absorption rates.

Polypropylene

Widely used polymer for non-wetted parts. Attacked by strong oxidizers, aromatic and chlorinated hydrocarbons.

PVDF

PVDF, polyvinylidene fluoride, has excellent resistance to most mineral and organic acids, aliphatic and aromatic hydrocarbons, and halogenated solvents. Poor resistance to acetone, MEK, THF, and potassium and sodium hydroxide. Often supplied as Kynar^®.