Polyolefin elastomers(PoE)

Polyolefin elastomers(PoE):

A number of investigation have tried to synthesis polyolefin block copolymers with molcular structure similar to the S-B-S triblock copolymer with S and B blocks replaced with crystallisable, elastomeric, poluolefin segments respectively.

[(E)-(E/P)]3-(E)

[(E/P)1-(E/P)2]3-(E/P)1

[(E)-(P)]3-(E)

Where the polyolefin blocks are ethylene (E), Propylene (P) and eithylene / propylene (E/P) sequences.

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Polyolefin elastomers (POE) are elastomers based on a polyethylene backbone. POEs offer low density and high flexibility and are commonly used to impact modify PE and PP compounds or to make PE and PP molded products more flexible. They can be used in injection molding, extrusion, film and compounding.

Polyolefin is an odorless, non-polar, and non-porous material that is used in structural plastics, consumer goods, industrial products, and food packaging. Polyolefin means “oil like” and is commonly referred to as a thermoplastic or polyalkene since polyolefin has a waxy texture.

Polyolefin elastomers:

1. Propylene/ α -olefin copolymers

2. High molecular weight stereoblock polypropylene

3. Graft copolymer of EPDM.

Propylene/ (alfa)-olefin copolymer -synthesis: Direct copolymerization of a-olefins A and B produces a copolymer with a structure of (A B y)n , x and A denoteds the monomer sequence length in particular segments n of a chain molecule.

High molecular weight stereo-block polypropylene:

The most recent and interesting development of a-olefin TPE is a composition derived from a homopolymer of polypropylene. The key factor which enables the production of an elastic propylene homopolymer or elastmeric polypropylene is the discovery of a class of stable catalyst based on absorption of transition metal organometallic compound on Al2O3. The polymerisation can be carried out in either batch or continuous process. In hydrocarbon medium or in liquid polypropylene.

Graft copolymer of EPDM:

An EPDM backbone grafted with a chemically dissimilar crystalline polypivalolactone is the only known exception where the crystalline phase is distinctly separated from the amorphous phase and the polypivalolactone crystals are dispsersed into smaller discreet domains over a wide composition range.

PoE- Applications:

1. Automotive - filler panels, bumper covers, fender extensions, flexible front and rear panels, corner panels, sight shields

2. Wire and cable- box gaskets, transformer encapsulation, cable ties, sleeving, caps, plugs, grommets and connectors.

3. Miscellaneous- belting, hose, fabric coating, seals, and various industrial molded goods.

Polyolefin Elastomers(PoE)-

General properties:

1. Being based on polyolefins, have the lowest specific gravities of all thermoplastic elastomers.

2. PoE’s are compatible with most olefinic materials

3. PoE’s are an excellent impact modifier

4. PoE’s are available in several grades having room temp. hardness ranging from 60 shore A to 60 shore D. 

5. PoE’s have emerged as a leading material for automotive interior and exterior applications.