Thermoplastic elastomers have a wide variety of uses in modern industry and commerce. Their chemical formula is very adaptable so that they can be formulated to be used in a variety of application.
What is TPE or Thermoplastic Elastomer?
A Thermoplastic elastomer, or TPE is a flexible and rubber-like material that processes like plastic. A TPE is a true thermoplastic, which does not require vulcanization or curing. Thermoplastic elastomers are processed using a variety of plastic manufacturing equipment such as, injection molding, extrusion, and blow molding. A TPE can be utilized in advanced processing such as, overmolding and two-shot molding, and can also undergo secondary operations such as, welding and bonding to various materials. Thermoplastic elastomers offer part design flexibility and easy bonding to other thermoplastic substrates.
There Are Four Generic Classes Of TPEs
|1||TPS or TPE-S||Thermoplastic elastomers described as TPS are compounds based on SBS or SEBS. In fact, the words SBS or SEBS are often used to describe these compounds when they are in fact raw materials. By describing compounds as SBS or SEBS it enables us to know the general level of performance and properties of the compound.|
|2||TPV or TPE-V||TPV compounds are the next step up in performance from TPO. These too are compounds of PP and EPDM rubber, however they have been dynamically vulcanised during the compounding step. They were originally conceived to bridge the gap between thermoplastic materials and vulcanised EPDM.|
They have seen strong growth in automotive seals, pipe seals, and other applications where a heat resistance of up to 120 degree C is required. Shore hardness values range typically from 45A to 45D. TPVs also lend themselves to under-bonnet automotive applications where improved temperature and oil resistance is required.
|3||TPO or TPE-O||TPO compounds are resin blends of polypropylene (PP) and un-crosslinked EPDM rubber and polyethylene. They are characterised by high impact resistance, low density and good chemical resistance.|
They are used in applications where there is a requirement for increased toughness and durability over the conventional PP copolymers, such as automotive bumpers and dashboards. The properties are restricted to the high end of the hardness scale, typically >80 Shore A and with limited elastomeric properties.
TPOs can be easily processed by injection moulding, extrusion or blow moulding.
|4||TPE-U or TPU||TPU or Thermoplastic Polyurethane are a category of plastic created when a polyaddition reaction occurs between diisocyanate and one or more diols. They can be used as a soft engineering plastic or as a replacement for hard rubber.|
Sample styrenic-based TPE formulations
|Sample “hard” styrenic-based TPE||Sample “soft” styrenic-based TPE|
|SEBS 100||SEBS 100|
|PP 60||Oil 100|
|Oil 200||Filler 100|
|Filler 100||Additives 10 – 30|
Typical formulations for TPO and TPV products
|Typical TPO||Typical TPV recipe range|
|Rubber 14 %||EPDM 30 – 50 %|
|PP 19 %||PP 5 – 20 %|
|Oil 30 %||Filler <10 %|
|Filler 35 %||Oil 20 – 35 %|