New Ethylene Copolymers Based on Single-Site Catalysts

9 New Ethylene Copolymers Based on Single-Site Catalysts 

Prior to the discovery of single-site catalysts the polyethylene industry was limited to conventional 1-olefins, primarily 1-butene, 1-hexene and 1 -octene, as comonomers that were used to control polyethylene properties. In this regard, the amoxmt and type of 1-olefin in the finished polymer were the important variables. 

This limitation changed with the introduction of single-site catalysts. Two commercial examples of new ethylene-based copolymers with novel olefins are ethylene copolymers based on norbornene and styrene. 

Kaminsky and coworkers foxmd that copolymerization of cyclopentene or norbornene with ethylene, using various metallocene compounds activated with MAO, produced new thermoplastic amorphous materials [55] that were transparent and had high stiffness and excellent stability. 

Unlike typical ethylene-based copolymers available in the polyethylene industry, which are semicrystalline materials, the ethylene norbornene copolymers are amorphous thermoplastic materials with a high heat distortion temperature of up to 170°C. They have a glossy, crystal clear appearance, with a high modulus (stiff material) and low shrinkage, which are important in the processability of the molten material. The high modulus of this copolymer is not unexpected. The polymer backbone due to the 

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