Compositions comprising EPDM and a polyolefin elastomer, preparation and use thereof
Provided are compositions comprising: (a) an ethylene-propylene-diene terpolymer having a Mooney viscosity [ML(1+4) 125° C.] of about 25 to about 300 and an ethylene content of at least about 60 wt % of the ethylene-propylene-diene terpolymer; and (b) a polyolefin elastomer. The presence of the polyolefin elastomer improves rheological properties of the composition to an extent that does not significantly compromise other properties, such as tensile strength at break and compression set.
1. A composition comprising:
(a) an ethylene-propylene-diene terpolymer having a Mooney viscosity [ML(1+4) 125° C.] of about 25 to about 300 and an ethylene content of at least about 60 wt % of the ethylene-propylene-diene terpolymer; and
(b) a polyolefin elastomer comprising at least about 60 wt % propylene-derived units and from about 5 to about 25 wt % ethylene-derived units, based on total weight of the polyolefin elastomer, and having a heat of fusion of less than about 80 J/g and an elongation at break of at least about 100% as determined by ASTM D412.
2. The composition of claim 1 , wherein the ethylene-propylene-diene terpolymer is present in an amount of about 10 to about 50 wt % of the composition.
3. The composition of claim 2 , wherein the polyolefin elastomer has a melt flow rate (ASTM D1238, 2.16 kg, 230° C.) of about 2 g/10 min to about 20 g/10 min.
4. The composition of claim 1 , wherein the polyolefin elastomer is present in an amount of less than about 150 phr relative to the ethylene-propylene-diene terpolymer.
5. The composition of claim 1 , wherein the polyolefin elastomer is present in an amount of less than about 100 phr relative to the ethylene-propylene-diene terpolymer.
6. The composition of claim 1 , wherein the polyolefin elastomer is present in an amount of less than about 50 phr relative to the ethylene-propylene-diene terpolymer.
7. The composition of claim 1 , wherein the polyolefin elastomer is present in an amount of less than about 20 phr relative to the ethylene-propylene-diene terpolymer.
8. The composition of claim 1 , further comprising at least one of a filler, a processing aid, a curing agent, and an accelerator.
9. The composition of claim 1 , further comprising sulfur.
10. The composition of claim 9 , wherein the sulfur is present in an amount of less than 5 phr relative to the ethylene-propylene-diene terpolymer.
11. The composition of claim 1 , further comprising a sulfur donor.
12. The composition of claim 1 , wherein the sulfur donor comprises at least one of tetramethylthiuram disulfide and dipentamethylenethiuram tetrasulfide.
13. The composition of claim 11 , wherein the sulfur donor is present in an amount of less than 5 phr relative to the ethylene-propylene-diene terpolymer.
14. The composition of claim 1 , wherein the composition has a Mooney viscosity [ML(1+4) 100° C.] about 0 to about 15 lower than the Mooney viscosity [ML(1+4) 100° C.] of a composition free of the polyolefin elastomer but is otherwise identical in terms of its constituents.
15. The composition of claim 1 , wherein the composition has at least one of the following properties:
(i) a tensile strength at break at most about 15% lower than the tensile strength at break of a composition free of the polyolefin elastomer but is otherwise identical in terms of its constituents; and
(ii) a compression set at most about 30% higher than the compression set of a composition free of the polyolefin elastomer but is otherwise identical in terms of its constituents.
16. A method for preparing a composition, comprising the steps of:
(a) combining (i) an ethylene-propylene-diene terpolymer having a Mooney viscosity [ML(1+4) 125° C.] of about 25 to about 300 and an ethylene content of at least about 60 wt % of the ethylene-propylene-diene terpolymer with (ii) a polyolefin elastomer comprising at least about 60 wt % propylene-derived units and from about 5 to about 25 wt % ethylene-derived units, based on total weight of the polyolefin-based elastomer, and having a heat of fusion of less than about 80 J/g and an elongation at break of at least about 100% as determined by ASTM D412, and
(b) forming the composition.
17. The method of claim 16 , further comprising the step of forming the composition into an article.
18. The method of claim 16 , wherein the composition has a Mooney viscosity [ML(1+4) 100° C.] about 0 to about 15 lower than the Mooney viscosity [ML(1+4) 100° C.] of a composition free of the polyolefin elastomer but is otherwise identical in terms of its constituents.
19. The method of claim 16 , wherein the composition has at least one of the following properties:
(i) a tensile strength at break at most about 15% lower than the tensile strength at break of a composition free of the polyolefin elastomer but is otherwise identical in terms of its constituents; and
(ii) a compression set at most about 30% higher than the compression set of a composition free of the polyolefin elastomer but is otherwise identical in terms of its constituents.
20. An article comprising the composition of claim 1 .
21. The article of claim 20 , wherein the article is an extruded article, molded article, hose, sheet, film, or jacket.
22. A composition comprising:
(a) an ethylene-propylene-diene terpolymer in an amount of about 20 to about 25 wt % of the composition having a Mooney viscosity [ML(1+4) 125° C.] of about 60 to about 90 wt %, and an ethylene content of about 60 to about 75 wt % of the ethylene-propylene-diene terpolymer;
(b) a propylene-based elastomer in an amount of about 5 to about 15 phr relative to the ethylene-propylene-diene terpolymer, comprising at least 60 wt % propylene and about 5 to about 25 wt % ethylene, based on total weight of the propylene-based elastomer, wherein the propylene-based elastomer has a heat of fusion of less than about 80 J/g and an elongation at break of at least about 100% as determined by ASTM D412;
(c) sulfur in an amount of about 0.5 phr relative to the ethylene-propylene-diene terpolymer;
(d) tetramethylthiuram disulfide in an amount of about 1 phr relative to the ethylene-propylene-diene terpolymer; and
(e) dipentamethylenethiuram tetrasulfide in an amount of about 1.5 phr relative to the ethylene-propylene-diene terpolymer.
23. A method for reducing the Mooney viscosity of a composition, comprising the steps of:
(a) combining (i) an ethylene-propylene-diene terpolymer having a Mooney viscosity [ML(1+4) 125° C.] of about 25 to about 300 and an ethylene content of at least about 60 wt % of the ethylene-propylene-diene terpolymer with (ii) a polyolefin elastomer having an elongation at break of at least about 100% as determined by ASTM D412, and
(b) forming the composition, wherein the composition formed has a Mooney viscosity [ML(1+4) 100° C.] about 0 to about 15 lower than the Mooney viscosity [ML(1+4) 100° C.] of a composition free of the polyolefin elastomer but is otherwise identical in terms of its constituents.