Thermoplastic elastomers and process for making same
A process for producing a thermoplastic elastomer composition, the process comprising synthesizing an elastomeric copolymer by polymerizing ethylene, an α-olefin, and optionally a diene monomer within the gas phase to thereby produce a gas-phase elastomeric copolymer, blending the gas-phase elastomeric copolymer with a thermoplastic polymer to form a mix of the elastomeric copolymer and thermoplastic polymer, and dynamically vulcanizing the gas-phase elastomeric copolymer within the mix of the elastomeric copolymer and thermoplastic polymer.
1. A process for producing a thermoplastic elastomer composition, said process comprising:
providing a granular elastomeric copolymer having dispersed therein carbon black, where said granular elastomeric copolymer is synthesized by using gas-phase polymerization; and
dynamically vulcanizing the granular elastomeric copolymer within a blend that includes the elastomeric copolymer and a thermoplastic polymer; where the Mooney Viscosity (ML(1+4@125° C.)) of the neat elastomeric copolymer is from about 200 to about 450.
2. The process of claim 1 , where said process is devoid of a step of granulating the elastomeric copolymer prior to said step of blending the elastomeric copolymer with the thermoplastic polymer.
3. The process of claim 1 , where the elastomeric copolymer includes from about 10 to about 40 parts by weight carbon per 100 parts by weight rubber.
4. The process of claim 1 , where the elastomeric copolymer has a particle size of about 0.4 to about 1.0 mm.
5. The process of claim 1 , where the blend also includes a conventionally synthesized elastomeric copolymer.
6. The process of claim 1 , where the elastomeric copolymer has a weight average molecular weight that is greater than about 200,000 and a number average molecular weight that is greater than about 80,000, and where the gas phase elastomeric copolymer is non-oil extended.
7. The process of claim 1 , where said step of dynamically vulcanizing the gas phase elastomeric copolymer is achieved with a phenolic cure system or a peroxide cure system.
8. The process of claim 1 , where the thermoplastic polymer is polypropylene.