Polyolefin Elastomer

Polyolefin elastomer (or POE) is a relatively new class of polymers that emerged with recent advances in metallocene polymerisation catalyst. It represents one of the fastest growing synthetic polymer. POE’s can be substituted for a number of generic polymers including ethylene propylene rubbers (EPR or EPDM), ethylene vinyl acetate (EVA), styrene-block copolymers (SBCs), and poly vinyl chloride (PVC).

Polyolefin elastomers are compatible with most olefinic materials, are an excellent impact modifier for plastics, and offer unique performance capabilities for compounded products.

Polyolefin elastomers are copolymers of ethylene and another alpha-olefin such as butene or octene. The metallocene catalyst selectively polymerises the ethylene and comonomer sequences and increasing the comonomer content will produce polymers with higher elasticity as the comonomer incorporation disrupts the polyethylene crystallinity. Furthermore, the molecular weight of the copolymer will help determine its processing characteristics and end-use performance properties with higher molecular weights providing enhanced polymer toughness.

Polyolefin elastomers are produced using refined metallocene catalyst often referred to as single-site or constrained geometry catalysts. These catalysts have a constrained transition metal (generally a Group 4B metal such as titanium, zirconium, or hafnium) sandwiched between one or more cyclopentadienyl ring structures to form a sterically hindered polymerisation site. This unique catalyst provides a single polymerisation site instead of the multiple sites of conventional catalysts and provides the capability to tailor the molecular architecture of ethylene copolymers. (Note: Metallocene catalysts and process technologies can also be used to produce ethylene propylene rubbers).

Polymerisation is very exothermic and requires efficient heat removal from the transport media of gas or solvent. Furthermore, reactor conditions must be carefully maintained to avoid loss of process control. Post-reactor processes involve additives addition and isolation of the polymer from the transporting media and the high catalyst efficiencies generally do not require removal of the deactivated catalysts. The final product is then packaged per manufacturer capability and end-user need, but can range from bags to railcars.

Source: The Institute of Synthetic Rubber Producers.

For more information on this source please visit The Institute of Synthetic Rubber Producers.