Plastomers are called engineering plastics too for areas of usage. There is no cross-linking structure in plastomers, unlike elastomers. So, although it is capable of deforming under load and returning to its original position, its speciality is much weaker than elastomers.
Thermoplastics with strong mechanical properties are used for metal materials unlike softer thermoplastics compete with elastomers in applications, and they are used in many different applications including sealing elements.
In seals, generally used plastomers are polyacetal (POM), polyamide (PA), polytetrafluoroethylene (PTFE or known as trade name Teflon®) materials. TPE (thermoplastic elastomer) is thermoplastic in structure, but it is a special material can be classified as an elastomer with its properties and performance.
PA
Polyamide (PA) ) is a high strength plastic. It has high abrasion resistance, hard material structure and dry working properties. For this reason, it is preferred various machine elements (gears, guide elements and so forth). It is used as a guide element or as a support ring in hydraulic-pneumatic systems like POM. Working temperature range and mechanical properties can be changed with special additives depending on where it is used. There are no reinforced type and glass fiber reinforced types.
In general, it shows high mechanical strength, good resistance to acids and bases, good radiation and UV resistance.
Proper using temperature range is from -40°C up to +85°C.
POM
Polyacetal (POM) is a thermoplastic with the high mechanical load resistance. Therefore, it is used as a guide element material or as support ring material in hydraulic-pneumatic systems. Depending on the application, types with or without glass fiber may be preferred.
They can be used in motor oils and HFA, HFB oils without any problem. Glass fiber reinforced types have higher mechanical strength.
Proper using temperature range is from -40°C up to +100°C. Can be used up to +140°C for short periods.
PTFE
Polytetrafluoroethylene (PTFE) is widely known with the trade name Teflon® and is widely used in many different sectors.
Surface tension is lower than most solids. In other words,its non-stick feature is very strong. Coefficient of static and dynamic friction is almost identical and as much as ‘ice’ in practice.
Its chemical resistance is better than all other elastomers and thermoplastics. It shows excellent swelling resistance in any environment. However, liquid alkalines and some fluorine compounds may adversely affect PTFE at high temperatures and pressures.
Pure PTFE is a good electrical insulator because of its low dielectric coefficient.
Additionally, in general applications, it is used as graphite, glass fiber, bronze and carbon added.
Proper using temperature range is from -200°C up to +260°C.
TPE
TPE (Thermoplastic elastomers) has elastomer specifications, but they are complex polymeric materials that can be processed and shaped like plastics.
For example, in a styrene-butadiene-styrene thermoplastic elastomer, the butadiene part is elastomeric, the styrene part is plastic. At high temperature styrene melts, the material becomes flowable. When cooled, the styrene hardens again. Can be reused with recycling.
Ester-based TPE is used as a back adaptor and support ring for seals in hydraulic and pneumatic systems. Excellent resistance to hydraulic oils and high flow strength are the defining characteristics of the material..
Other than this, high tensile strength, good elasticity, resistance to solvents, oxidative acid, aliphatic hydrocarbons, alkaline solutions and resistance to various kinds of greases and oils are other characteristics of the material. Proper using temperature range is from -40°C up to +120°C.