Thermoplastic vulcanizate compositions
In another embodiment, a TPV composition includes an ethylene based copolymer, a thermoplastic polyolefin, and one or more of an oil or a plasticizer. The ethylene based copolymer has an Mw of from 400,000 g/mol to 3,000,000 g/mol, a Mw/Mn of 10 or less, and a g′ vis of 0.7 or more. An amount of the one or more of an oil or a plasticizer in the TPV composition is from 10 parts by weight to 200 parts by weight per 100 parts by weight of the ethylene based copolymer, and the TPV composition has an extrusion surface roughness that is from 50 μin to 120 μin. In another embodiment is provided a method of forming a TPV composition. In another embodiment is provided a method of forming an article that includes a TPV composition. In another embodiment is provided an article that includes a TPV composition.
1 . A thermoplastic vulcanizate (TPV) composition, comprising:
an ethylene based copolymer, wherein the ethylene based copolymer has an Mw of from 400,000 g/mol to 3,000,000 g/mol, a Mw/Mn of 10 or less, a Δδ of from 30 to 80 degrees from small amplitude oscillatory shear (SAOS) where Δδ=δ(0.1 rad/s)−δ(128 rad/s), and a g′ vis of 0.7 or more;
a thermoplastic polyolefin; and
one or more of an oil or a plasticizer, wherein an amount of the one or more of an oil or a plasticizer in the TPV composition is from 10 parts by weight to 200 parts by weight per 100 parts by weight of the ethylene based copolymer.
2 . The TPV composition of claim 1 , wherein the thermoplastic polyolefin has a g′ vis of 0.9 or more.
3 . The TPV composition of claim 1 , wherein the thermoplastic polyolefin has a g′ vis of less than 0.9.
4 . The TPV composition of claim 1 , wherein the ethylene based copolymer is an ethylene-propylene-diene terpolymer.
5 . The TPV composition of claim 1 , wherein the oil is a mineral oil, a synthetic oil, an ester plasticizer, or a combination thereof.
6 . The TPV composition of claim 5 , wherein the mineral oil is a Group II oil, a total amount of aromatic compounds and polar compounds in the oil is less than 4.5 wt % as measured according to ASTM 2007, and a viscosity of the oil is at least 80 cSt at 40° C.
7 . The TPV composition of claim 1 , further comprising a compatibilizer, a filler, a nucleating agent, or a combination thereof.
8 . The TPV composition of claim 1 , further comprising a curative.
9 . The TPV composition of claim 1 , wherein the ethylene based copolymer has an ethylene content of from 50 wt % to 70 wt % based on a total weight of the ethylene based copolymer.
10 . The TPV composition of claim 1 , wherein the thermoplastic polyolefin has:
a melt mass flow rate (ASTM D1238; 230° C.; 2.16 kg) of from 0.1 g/10 min to 50 g/10 min; and
a Mw of from 100,000 g/mol to 1,000,000 g/mol.
11 . The TPV composition of claim 1 , wherein the composition has a hardness of from 20 Shore A to 60 Shore D.
12 . The TPV composition of claim 1 , wherein the composition has a G′ value (@ 90° C., 0.6 rad/s, and 1% strain) of from 600 kPa to 2000 kPa.
13 . The TPV composition of claim 1 , wherein the composition has a capillary viscosity of 120 Pa s or less, as measured at 204° C. and a shear rate of 1,200 s −1 .
14 . The TPV composition of claim 1 , wherein the ethylene based copolymer of the TPV composition has a large amplitude oscillatory shear (LAOS) branching index of less than 3.
15 . The TPV composition of claim 1 , wherein the TPV composition has a tension set of less than 16%.
16 . The TPV composition of claim 1 , wherein the ethylene based copolymer has a dry Mooney Viscosity (ML 1+4 @ 125° C.) of 250 MU or greater.
17 . The TPV composition of claim 1 , wherein the ethylene based copolymer has a LCB index (@ 125° C.) of 2.5 or lower.
18 . The TPV composition of claim 1 , wherein the ethylene based copolymer has a Δδ of 32 degrees or greater, where Δδ=δ(0.1 rad/s)−δ(128 rad/s).
19 . The TPV composition of claim 1 , wherein the ethylene based copolymer is oil extended with an oil having 50 phr to 200 phr based on 100 phr of the ethylene based copolymer.
20 . The TPV composition of claim 1 , wherein the ethylene based copolymer content is from 10 wt % to 90 wt % based on a total weight of TPV composition.
21 . The TPV composition of claim 1 , wherein the TPV composition has a stress relaxation slope of −1 to −5 (1/min) as measured by an Elastocon stress relaxation instrument.
22 . The TPV composition of claim 1 , wherein the TPV composition has a tan δ value (@ 215° C., 5.0 rad/s, and 100% strain) of from 0.25 to 1.0.
23 . A method of making a TPV composition, comprising:
introducing an ethylene based copolymer having a Δδ of from 30 to 80 degrees from small amplitude oscillatory shear (SAOS) where Δδ=δ(0.1 rad/s)−δ(128 rad/s) to an extrusion reactor;
introducing a thermoplastic polyolefin to the extrusion reactor;
introducing a filler, an additive, or a combination of filler and additive to the extrusion reactor;
introducing a first amount of one or more of an oil or a plasticizer to the extrusion reactor before a curative;
introducing the curative to the extrusion reactor;
introducing a second amount of one or more of an oil or a plasticizer to the extrusion reactor after the curative, wherein 3 wt % to 37 wt % of a total amount of the one or more of an oil or a plasticizer is added to the extrusion reactor before the curative and 63 wt % to 97 wt % of the total amount of the one or more of an oil or a plasticizer is added to the extrusion reactor after the curative; and
dynamically vulcanizing the ethylene based copolymer with the curative in the presence of the thermoplastic polyolefin to form a TPV composition.
24 . The method of claim 23 , further comprising introducing a filler, an additive, or a combination of filler and additive to the extrusion reactor.
25 . The method of claim 23 , wherein a weight ratio of the second amount of one or more of an oil or a plasticizer to the first amount of one or more of an oil or plasticizer is from 2:1 to 10:1.
26 . An article formed from the TPV composition of claim 1 , wherein the article has an extrusion surface roughness that is from 50 μin to 120 μin.