TPE/TPR Resin

Thermoplastic Elastomer (TPE Resin) is a general term that describes any thermoplastic that has elastomeric properties similar to rubber.

There a currently 7 different thermoplastics classified as TPE Resins:

 

  1. Styrenic Block Copolymers (SBC)
  2. Thermoplastic Polyolefins (TPO)
  3. Thermoplastic Vulcanizate (TPV)
  4. Thermoplastic Polyurethanes (TPU)
  5. Thermoplastic Copolyesters (TPC-ET or COPE or TPEE)
  6. Thermoplastic Polyamides (TPA-ET or PEPA or PEBA)
  7. Flexible Polyvinyl Chloride (PVC)

Each of these TPE materials has unique properties and there are a wide variety of applications that they are used for. SBC is used for tooth brush handles, gaskets for jars and mobile phone cases. It is available in clear unlike the other TPE materials. TPO is used for automotive bumper fascia’s and automotive interior panels. TPV has a feel that is closest to rubber and is used for gaskets, rubber bumpers and grommets. TPU has the highest tensile strength of any TPE resin and is commonly used for automotive suspension bushings and dog chew toys. Thermoplastic copolyesters are higher heat and higher stiffness than other TPE resins and are used for automotive CV joint boots and coiled pneumatic tubing. Thermoplastic polyamides are specialty TPE’s which are used primarily for medical applications. PVC is used in sheet form as a synthetic leather for automotive dash board covers and seating and furniture.

To learn more about the advantages of TPE resin vrs. the advantages of rubber go here. For more information about the TPE plastic resins we have available for distribution, please contact us.

 

If you have an application that would be better suited to TPE resins, there are a number of different types:

 

1. Styrene Block Copolymers (SBC)

What is it: SBC (styrene block copolymer) materials are block copolymers and terpolymers (more than two polymers) of styrene and butadiene (pronounced byoot-u-dy’-een). This is a broad category of materials that covers a number of different formulations. Material designated as SBS, SEBS, SEPS, SIS and SEP are all styrenic block copolymers. You can look up what all those acronyms stand for if you want but I won’t bore you. Some manufacturers just refer to their material as SBC which means they’re being a bit cagey about the exact make-up of the material. A book could be written about the differences between all of the different SBC formulations but there are more similarities than differences so I will just cover the basics here. SBC materials are not typically injection moldable so most commercial grades are SBC that is compounded with polypropylene or polyethylene.

Here are the highlights:

  • Hardness range from 15 Shore A to 50 Shore D
  • The softest TPE resin available
  • Good glossy appearance with a smooth surface feel similar to polypropylene
  • Highest tensile elongation of any TPE (stretchiest)
  • Available in clear
  • Less heat resistant than TPV
  • More flexible than TPV
  • Poor chemical resistance to oil.
  • Maximum continuous service temperature 230F
  • Common trade names include Kraton, Sunprene, Multiflex
  • Applications include gel inserts for shoes, grips for pens and toothbrushes and appliance knobs

 

2. Thermoplastic Polyolefin (TPO)

What is it: TPO is a compounded blend of polypropylene and non-cross-linked EPDM rubber. TPOs are sometimes filled with mineral fillers or, occasionally, glass fiber. These tend to be harder materials ranging from 30 Shore D and up. They tend to be classified by flexural modulus rather than hardness. There are also some grades of TPO that are referred to as “reactor TPO”. These are typically very high impact polypropylene copolymers that are just referred to as TPO because the properties are quite a bit different than most polypropylenes.

Here are the highlights:

  • Available in flexural modulus from 90,000 to 350,000 psi.
  • Combination of high stiffness and high impact strength
  • Excellent appearance
  • Some grades are paintable
  • Weatherable grades are available
  • Maximum continuous service temperature 230F
  • Common trade names include Hifax, Mytex, Polyfort
  • Applications include automotive bumper fascias, automotive interior panels

 

3. Thermoplastic Vulcanizate (TPV)

What is it: TPV is a compounded blend of polypropylene and cross-linked EPDM rubber. TPV tends to be very soft and flexible. It is similar in properties to SBC.

Here are the highlights:

  • Hardness range from 35 Shore A to 50 Shore D
  • Has a matt finish appearance and a very rubber like feel
  • Not available in clear. Natural TPV is a light cream color similar to ABS.
  • Not as flexible as SBC
  • More heat resistant than SBC
  • Good chemical resistance
  • Runs better if dried but many molders do not dry it
  • Maximum continuous service temperature 240 F
  • Common trade names include Santoprene, Geolast, Sarlink, Trexprene
  • Applications include power tool housings, automotive boots and grommets, automotive cup holder inserts, door bumpers
  • More expensive than SBC

 

4. Thermoplastic Polyurethane (TPU)

What is it: TPU materials are block copolymers formed by the reaction of diisocyanates with short chain diols or long chain diols. They are the best wearing TPE materials and have the highest tensile strength.

Here are the highlights:

  • Hardness range from 70 Shore A to 80 Shore D
  • The best compression set or rebound of any TPE
  • The best wear properties of any TPE
  • High tensile strength, even for softer grades
  • High tear strength
  • Must be dried
  • Difficult to mold, degrades easily
  • Annealing parts improves performance
  • Expensive
  • Ester based grades are most common and offer the best properties
  • Ether based grades offer better hydrolysis resistance
  • Heavier than other TPEs with a density around 1.24 g/cm³
  • Maximum continuous service temperature 200 F
  • Common trade names include Elastollan, Desmopan, Estane, Irogran, Texin
  • Applications include in-line skate and skateboard wheels, automotive suspension bushings, running shoe arch supports and medical tubing

 

5. Thermoplastic Copolyesters (TPC-ET or COPE)

What is it: TPC-ET materials are copolymers of bifunctional aromatic polyesters. They are the highest heat TPEs available and can take repeated bending forces without breaking.

Here are the highlights:

  • Hardness range from 80 Shore A to 80 Shore D
  • Higher stiffness than other TPEs
  • Can be repeatedly flexed without fracture
  • Maximum continuous service temperature 290 F
  • Common trade names include Hytrel, Arnitel
  • Applications include automotive CV joint boots, coiled air hose tubing

 

6. Thermoplastic Polyamides (TPA-ET or PEPA or PEBA)

What is it: TPA-ET materials are copolymers obtained by polycondensation of a carboxylic acid poyamide with alcohol terminated polyether. Think of it as nylon based TPE. It offers properties similar to TPC-ET. This is not a commonly used material that seems to find a home mostly in medical applications.

Here are the highlights:

  • Hardness range from 80 Shore A to 70 Shore D
  • Can be repeatedly flexed without fracture
  • Good oil resistance, even at high temperatures
  • Expensive
  • Maximum continuous service temperature 290 F
  • Common trade names include Vestamid
  • Applications include breathable films and medical tubing.

 

7. Polyvinyl Chloride (PVC)

What is it: PVC is produced by polymerization of vinyl chloride monomer. Plasticizers, primarily phthalates, are blended into the material to make it soft and flexible. Unlike the other materials here, PVC is available in both a rigid and a flexible form. We will focus on the flexible version here.

Here are the highlights:

  • Hardness range from 35 Shore A to 55 Shore D
  • Excellent chemical resistance
  • Excellent appearance
  • Very poor heat resistance
  • Poor compression set or rebound
  • Heavier than other TPEs, with density around 1.25 g/cm³
  • Available in clear
  • Poor wear and tear strength properties
  • There are concerns about plasticizers causing adverse health effects
  • Maximum continuous service temperature 176 F
  • Common trade names include Geon, Hy-Vin, Polyvin, Vinika
  • Applications include tubing, flooring, automotive interior panel covering

 

8. Ionomer

What is it: Ionomers are ethylene acid copolymers that use ionic bonds in the molecular chains. The ionic bonds make these material behave more like thermosets at room temperature but more like elastomers at low temperatures.

Here are the highlights:

  • Hardness range from 35 Shore D to 70 Shore D
  • High Impact Strength
  • Excellent low temperature impact strength
  • Excellent abrasion resistance
  • Poor heat resistance: Maximum continuous service temperature 118 F
  • Good chemical resistance
  • Available in clear
  • Common trade names include Surlyn

Applications include golf ball covers, cosmetics containers, food packaging film. Also used as an impact modifier for nylon.

 

The typical brands of TPE plastic resin offered by Midwest Resins are:

  • Viprene TPV
  • Zythane TPV
  • Buckeye Polymers BP Flex TPO and TPV
  • Kolon Kopel TPC-ET
  • Colormaster PVC
  • Elastron SBC, TPV and TPO
  • IPC Specialty Products TPO
  • MRC Polymers Maxtel TPO

At MidWest Resins, we carry a number of different TPEs in stock and can help you pick the right material for your application.