Thermoplastic compositions comprising recycled polymers and articles manufactured therefrom
In various embodiments, a thermoplastic composition may comprise from 0.5 wt. % to 75.0 wt. % of recycled polyethylene comprising a blend of polyethylene recovered from post-consumer material, pre-consumer material, or combinations thereof, and from 25.0 wt. % to 99.5 wt. % of virgin raw polyethylene comprising unimodal polyethylene, bimodal polyethylene, or combinations thereof, wherein at least 90.0 wt. % of the thermoplastic composition is comprised of the post-consumer recycled polyethylene and the virgin raw polyethylene. Manufactured articles made from the thermoplastic composition, such as coated conductors, are also provided.
1 . A thermoplastic composition comprising: from 0.5 wt % to 75.0 wt. % of a recycled polyethylene comprising a blend of polyethylene recovered from post-consumer material, pre-consumer material, or combinations thereof; and from 25.0 wt. % to 99.5 wt % of virgin raw polyethylene comprising unimodal polyethylene, bimodal polyethylene, or combinations thereof, wherein:
the recycled polyethylene has:
a density of from 0.920 g/cm 3 to 0.975 g/cm 3 when measured according to ASTM D792-08, Method B;
a melt index (I 2 ) of from 0.30 dg/min to 3.00 dg/min when measured according to ASTM D1238-10, Method B, at 190° C. and a 2.16 kg load;
a melt flow ratio (MFR 21 ) greater than or equal to 50, wherein the melt flow ratio (MFR 21 ) is a ratio of a high load melt index (I 21 ) of the recycled polyethylene to the melt index (I 2 ), and the high load melt index (I 21 ) is measured according to ASTM D1238-10, Method B, at 190° C. and a 21.6 kg load;
a melting point (T m ) of from 105° C. to 135° C. when measured by Dynamic Scanning calorimetry (DSC) according to ASTM D3418-15; and
from 0.1 wt. % to 10 wt. % of polymer chains having a logarithm molecular weight (Log M) less than 2.5 when measured using gel permeation chromatography (GPC);
the unimodal polyethylene has:
a density of from 0.930 g/cm 3 to 0.950 g/cm 3 when measured according to ASTM D792-08, Method B;
a melt index (I 2 ) of from 0.30 dg/min to 1.00 dg/min when measured according to ASTM D1238-10, Method B, at 190° C. and a 2.16 kg load; and
a melt flow ratio (MFR 21 ) greater than or equal to 30, wherein the melt flow ratio (MFR 21 ) is a ratio of a high load melt index (I 21 ) of the unimodal polyethylene to the melt index (I 2 ), and the high load melt index (I 21 ) is measured according to ASTM D1238-10, Method B, at 190° C. and a 21.6 kg load;
the bimodal polyethylene has:
a density of from 0.933 g/cm 3 to 0.960 g/cm 3 when measured according to ASTM D792-08, Method B;
a melt index (I 2 ) of from 0.30 dg/min to 2.00 dg/min when measured according to ASTM D1238-10, Method B, at 190° C. and a 2.16 kg load;
a melt flow ratio (MFR 21 ) greater than or equal to 80.0, wherein the melt flow ratio (MFR 21 ) is a ratio of a high load melt index (I 21 ) of the bimodal polyethylene to the melt index (I 2 ), and the high load melt index (I 21 ) is measured according to ASTM D1238-10, Method B, at 190° C. and a 21.6 kg load;
a molecular weight distribution (M w /M n ) greater than or equal to 6, wherein the molecular weight distribution (M w /M n ) is a ratio of a weight average molecular weight (M w ) of the bimodal polyethylene to a number average molecular weight (M n ) of the bimodal polyethylene, and the weight average molecular weight (M w ) and the number average molecular weight (M n ) are measured using gel permeation chromatography (GPC); and
a reverse comonomer distribution, wherein a ratio of a short chain branching distribution of the high molecular weight component (SCBD 2 ) to a short chain branching distribution of the low molecular weight component (SCBD 1 ) is greater than 1.0, and the short chain branching distribution of the high molecular weight component (SCBD 2 ) and the short chain branching distribution of the low molecular weight component (SCBD 1 ) are measured using gel permeation chromatography (GPC); and
at least 90.0 wt. % of the thermoplastic composition is comprised of the recycled polyethylene and the virgin raw polyethylene.
2 . The thermoplastic composition of claim 1 , wherein the unimodal polyethylene has a melting temperature (T m ) of from 120° C. to 130° C. when measured by Dynamic Scanning calorimetry (DSC) according to ASTM D3418-15.
3 . The thermoplastic composition of claim 1 , wherein the virgin polyethylene is the unimodal polyethylene.
4 . The thermoplastic composition of claim 1 , wherein the virgin raw polyethylene is the bimodal polyethylene.
5 . The thermoplastic composition of claim 1 , further comprising up to 10 wt. % of one or more additives, based on the total weight of the thermoplastic composition.
6 . The thermoplastic composition of claim 5 , wherein the additives comprise 0.01 wt. % to 0.5 wt. % of antioxidant, based on the total weight of the thermoplastic composition.
7 . The thermoplastic composition of claim 5 , wherein the additives comprise 0.05 wt. % to 9 wt. % carbon black, based on the total weight of the thermoplastic composition.
8 . The thermoplastic composition of claim 1 , wherein the thermoplastic composition comprises 5.0 wt. % to 50.0 wt. % of the recycled polyethylene and from 45.0 wt. % to 95.0 wt. % of the virgin raw polyethylene.
9 . A method of making the thermoplastic composition of claim 1 , the method comprising melt-blending the recycled polyethylene, the virgin polyethylene, and any optional additives, thereby making the thermoplastic composition.
10 . A manufactured article comprising the thermoplastic composition of claim 1 .
11 . The manufactured article of claim 10 , wherein the thermoplastic composition exhibits one or more of the following:
an average tensile strength at break greater than or equal to 1,400 psi when measured according to ASTM D638-14, Type IV;
an elongation at break greater than or equal to 200% when measured according to ASTM D638-14, Type IV;
an environmental stress-cracking resistance (ESCR) (F 0 ) greater than or equal to 24 hours when measured according to ASTM D1693-1, Method B, in a 10% Igepal solution at 50° C.; and a secant modulus (E s ) greater than 450 MPa when measured according to ASTM D790-17.
12 . The manufactured article of claim 10 , further comprising a coating and a support component, wherein the coating comprises the thermoplastic composition and is disposed on or in the support component.
13 . A coated conductor comprising a coating layer and a conductive core, wherein the coating layer comprises the thermoplastic composition of claim 1 and covers at least a portion of the conductive core.
14 . A method of transmitting electricity and/or light through a conductive core of the coated conductor of claim 13 , wherein the conductive core comprises a metallic wire, an optical fiber, or both; the method comprising step (a) and/or step (b): (a) applying a voltage across the metallic wire, thereby causing electrical energy to flow through the metallic wire; and/or (b) sending a pulse of light through the optical fiber, thereby causing light to transmit through the optical fiber; thereby transmitting electricity and/or light, respectively, through a conductive core of the coated conductor.