RELATED APPLICATION

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. provisional application number 63/333,264, filed April 21, 2022, which is incorporated by reference herein in its entirety.

STATEMENT OF GOVERNMENT SUPPORT

[0002] This invention was made with government support under grant number CHE1901635 awarded by the National Science Foundation. The government has certain rights in the invention.

TECHNICAL FIELD

[0003] This invention relates to reactive additives for recycling mixed plastic waste.

BACKGROUND

[0004] Plastics can re-enter the supply chain by chemical and mechanical recycling.

Chemical recycling includes breaking down plastic materials into their substituent monomer units, which can then be repolymerized and used again. Mechanical recycling includes melt reprocessing of plastic waste into new products. Mixed plastic waste includes different types of plastics, such as polyethylene terephthalate (PET) and linear low-density polyethylene (LLDPE).

SUMMARY

[0005] This disclosure generally relates to reactive additives for recycling mixed plastic waste. In particular, this disclosure describes compatibilization of blends of plastics from mixed plastic waste, such as polyethylene terephthalate (PET) and polyolefins (POs) (e.g., polyethylene (PE) including linear low density polyethylene (LLDPE) and high density polyethylene (HDPE), and polypropylene (PP), including isotactic polypropylene (iPP)) with telechelic polyolefin additives. Examples of suitable additives include hydroxy telechelic (hydroxy-terminated) polyolefins such as PE (HOPEOH) (e.g., for blends of PET and PE) and hydroxy poly(ethylene/ethyl ethylene) (HOPEEEOH) (e.g., for blends of PET and PP). The additives can be prepared by ring-opening metathesis polymerization (e.g., of cyclooctene) or anionic polymerization (e.g., of butadiene) followed by catalytic hydrogenation. The telechelic polyolefin additive provides compatibilization at a low loading (e.g., less than 5 wt% or less than 1 wt%), without the production of volatile leaving groups. The relevant reactions take place in situ during melt reprocessing/extrusion of the blend polymers with the reactive additives and can occur in the absence of a catalyst. In this disclosure, “wt%” and “wt/wt” are used interchangeably.

[0006] The use of hydroxy telechelic polyethylene additives for compatibilizing immiscible PET/LLDPE 80/20 wt% blends was demonstrated. Blends containing these additives showed evidence of successful compatibilization (increased mechanical toughness and decreased average droplet diameter) at low loadings (0.5 wt%). Partial compatibilization (characterized by a larger spread in the mechanical properties and a slightly increased average droplet size) was shown at lower concentrations (0.2 wt%). These additives were effective at molecular weights below the critical molecular weight M _c , which may be attributed to their ability to form trapped entanglements with LLDPE homopolymer due to conformation of the resulting copolymer.

These difimctional additives showed success in compatibilizing blends of post-consumer PET/PE at low loadings.

[0007] The details of one or more embodiments of the subject matter of this disclosure are set forth in the accompanying drawings and the description. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

[0008] FIG. lAis a schematic showing compatibilization of PET and LLDPE with HOPEOH. FIG. IB is a schematic showing compatibilization of PET and iPP with HOPEEEOH. FIG. 1C shows the proposed mechanism by which the resultant copolymers impart interfacial toughness while being below the critical molecular weight M _c .

[0009] FIG. 2A shows representative tensile stress-strain data for PET and LLDPE homopolymers and blends of the two materials with and without HOPEOH additives. Fracture point notated with star (★). FIG. 2B shows strain at break values for PET homopolymer (dashed line) and blends (points). Error bars represent the standard deviation of all samples tested at an individual blend composition. [0010] FIGS. 3A-3F are SEM images of neat (FIGS. 3A-3C) and compatibilized (HOPEOH- 4k 0.5 wt%) (FIGS. 3D-3F) blends after mixing (FIGS. 3A and 3D), annealing into films (FIGS. 3B and 3E), and testing (FIGS. 3C and 3F). Deformed LLDPE droplets are outlined in red in FIG. 3F.

[0011] FIGS. 4A and 4B show measured droplet diameters as-mixed and annealed blends, respectively. Values reported are the average of at least 50 droplets measured using ImageJ, with error bars representing the standard deviation of the samples.

[0012] FIG. 5A shows tensile data of PET homopolymer and blends of PET/LLDPE, without additive or with either monohydroxy-terminated polyethylene (PEOH) or dihydroxy terminated polyethylene (HOPEOH) reactive additives at comparable hydroxyl concentrations. Fracture point notated with star (★). FIGS. 5B and 5C show SEM of tested samples for PEOH-3k (FIG. 5B) and PEOH- 15k (FIG. 5C).

[0013] FIG. 6 shows representative tensile data for recycled PET (rPET), LLDPE (rLLDPE), and HDPE (rHDPE) homopolymer materials as well as uncompatibilized and compatibilized rPET/rLLDPE and rPET/rHDPE blends. Fracture point notated with star (★).

[0014] FIG. 7 shows tensile data for PET, PP, a neat 80/20 blend of PET and PP, and an 80/20 blend of PET and PP compatibilized with 2 wt% HOPEEEOH (batch mix and stage mix). Fracture points notated with an asterisk (*).

[0015] FIGS. 8A and 8B are SEM images of the neat blend described with respect to FIG. 7. FIGS. 8C and 8D are SEM images of the compatibilized blend described with respect to FIG. 7. [0016] FIG. 9 shows tensile data for an 80/20 blend of PET and PP compatibilized with 5 wt% HOPEEEOH (stage mix). Fracture points notated with an asterisk (*). Individual lines and fracture points correspond to different samples cut from the same film.

[0017] FIG. 10 is an SEM image of the blend described with respect to FIG. 9.

[0018] FIG. 11 shows tensile stress for an 80/20 blend of PET and PP compatibilized with an load of 5 wt% HOPEEEOH and an increased mixing intensity (150 RPM). Fracture points notated with an asterisk (*). Individual lines and fracture points correspond to different samples cut from the same film. DETAILED DESCRIPTION

[0019] When disparate polymers from different products are blended together, they form a macrophase-separated blend. These blends are usually more brittle than their virgin components, making them undesirable for applications like packaging. Therefore, recycling streams are typically first presorted by material, which is not applicable for all materials (e.g., multilayer films), and can be costly and imperfect. Mixed polymers blends can be improved by compatibilizing the components in the blend.

[0020] This disclosure describes compatibilization of blends of plastics from mixed plastic waste, such as polyethylene terephthalate (PET) and polyolefins (POs) (e.g., polyethylene (PE), including HDPE and LLDPE, and polypropylene (PP), including isotactic polypropylene (iPP)). [0021] Suitable additives include telechelic polyolefins, such as dihydroxy PE (HOPEOH) (e g , for blends of PET and PE) and dihydroxy poly(ethylene/ethyl ethylene) (HOPEEEOH) (e.g., for blends of PET and PP). The disclosed telechelic polyolefin additive provides compatibilization at a low loading (e.g., less than 5 wt%, or less than 1 wt%), without the production of volatile leaving groups. The relevant reactions take place in situ during melt reprocessing/extrusion of the blend polymers with the reactive additives and can occur in the absence of a catalyst.

[0022] FIG. 1A depicts compatibilization of PET and LLDPE with HOPEOH, in which the HOPEOH reacts with PET in situ to form a copolymer additive at the PET/LLDPE interface. FIG. IB depicts compatibilization of PET and iPP with HOPEEEOH, in which HOPEEEOH reacts with PET in situ to form a copolymer additive at the PET/iPP interface.

[0023] Without wishing to be bound by theory, FIG. 1C depicts a compatibilization mechanism. On the left of FIG. 1C are graphical representations of PET, LLDPE, and HOPEOH. Note that PET homopolymer chains contain many ester groups, but only one is shown for clarity. During melt mixing, HOPEOH can localize at the PE/PET interface where one chain end can undergo a transesterification reaction with PET homopolymer. The opposite chain end of a tethered HOPEOH can react with another PET ester to complete the loop. Upon cooling, PE homopolymer chains may become entrapped by the resultant loop and anchor the loop in the PE homopolymer phase while PET chain ends can undergo co-crystallization or bulk entanglements with the PET homopolymer. [0024] Provided herein is a method of making a polymer composite. The method comprises combining polyethylene terephthalate, polyolefin, and a hydroxy telechelic polyolefin additive to yield a mixture; compounding the mixture to yield a blend comprising a polyethylene terephthalate homopolymer, a polyolefin homopolymer, and a copolymer comprising a reaction product of the hydroxy telechelic polyolefin and the polyethylene terephthalate; and extruding the blend to yield the polymer composite.

[0025] In some embodiments, the polyolefin comprises polyethylene. In some embodiments, the polyethylene comprises LLDPE, HDPE, or a combination thereof. In some embodiments, the polyolefin comprises polypropylene. In some embodiments, the polypropylene comprises isotactic polypropylene.

[0026] In some embodiments, the hydroxy telechelic polyolefin additive is synthesized by a ring-opening metathesis polymerization of cyclooctene followed by catalytic hydrogenation. In some embodiments, the hydroxy telechelic polyolefin additive is synthesized by an anionic polymerization of butadiene followed by catalytic hydrogenation.

[0027] In some embodiments, the hydroxy telechelic polyolefin additive comprises a dihydroxy polyethylene (HOPE OH) or a dihydroxy poly(ethylene/ethylethylene) (HOPEEEOH).

[0028] In some embodiments, the mixture comprises 5 wt% or less of the hydroxy telechelic polyolefin additive. In some embodiments, the mixture comprises 2 wt% or less of the hydroxy telechelic polyolefin additive. In some embodiments, the mixture comprises 1 wt% or less of the hydroxy telechelic polyolefin additive.

[0029] In some embodiments, a molecular weight of the hydroxy telechelic polyolefin additive is in a range of Ik to 25k g/mol.

[0030] In some embodiments, the mixture does not include a catalyst. In some embodiments, the mixture does not include polylactic acid.

[0031] In some embodiments, the polyethylene terephthalate and polyolefin are post-consumer plastics.

[0032] In some embodiments, the hydroxy telechelic polyolefin additive is combined with at least some of the polyethylene terephthalate to yield a precursor, and the polyolefin is combined with the precursor to yield the mixture.

[0033] In some embodiments, the polyolefin comprises two or more different polyolefins. In some embodiments, the two or more different polyolefins comprise PE and iPP. [0034] In some embodiments, the mixture comprises an additional polymer. In some embodiments, the additional polymer comprises nylon.

[0035] Also provided herein is a copolymer comprising a polyethylene terephthalate block; and a polyolefin block, wherein the copolymer is a reaction product of a polyethylene terephthalate copolymer and a hydroxy telechelic polyolefin additive.

[0036] In some embodiments, the copolymer is a multiblock copolymer having formula [polyethylene terephthalate] -[polyolefin] -[polyethylene terephthalate]. In some embodiments, the copolymer is a triblock copolymer. In some embodiments, the copolymer is a triblock PET-PE- PET copolymer.

[0037] In some embodiments, the polyolefin comprises polyethylene. In some embodiments, the polyethylene comprises LLDPE, HDPE, or a combination thereof.

[0038] In some embodiments, the polyolefin comprises polypropylene. Tn some embodiments, the polypropylene comprises isotactic polypropylene.

[0039] In some embodiments, the hydroxy telechelic polyolefin additive comprises HOPEOH or HOPEEEOH. In some embodiments, a molecular weight of the hydroxy telechelic polyolefin additive is in a range of Ik to 25k g/mol.

[0040] In some embodiments, the polyethylene terephthalate is a post-consumer plastic.

[0041] In some embodiments, the copolymer further comprises an additional polyolefin block. In some embodiments, the polyolefin block comprises PE and the additional polyolefin block comprises iPP.

[0042] In some embodiments, the copolymer further comprises an additional polymer block. In some embodiments, the additional polymer block comprises nylon.

[0043] Also provided herein is a polymer composite formed by a method disclosed herein.

[0044] Also provided herein is a polymer composite comprising polyethylene terephthalate; polyolefin; and a copolymer described herein.

[0045] In some embodiments, the polyolefin comprises two or more different polyolefins.

[0046] In some embodiments, the polymer composite further comprises an additional polymer.

[0047] Also provided herein is a polymer composite comprising post-consumer polyethylene terephthalate; post-consumer polyolefin; and a copolymer comprising a reaction product of the hydroxy telechelic polyolefin and the post-consumer polyethylene terephthalate.

[0048] In some embodiments, the copolymer is formed in situ. [0049] In some embodiments, the post-consumer polyolefin comprises two or more polyolefins. In some embodiments, the two or more polyolefins comprise PE and iPP.

[0050] In some embodiments, the polymer composite further comprises an additional polymer. In some embodiments, the additional polymer comprises nylon.

EXAMPLES

Materials and Methods

[0051] Materials. PET and LLDPE pellets were used as received. The PET pellets were sourced from Toray Plastics America. The LLDPE pellets were sourced from Exxon (LL3003.32, melt flow index = 3.2/10 min at 190 °C/2.16 kg). CA-hexadec-6-ene-l,16-diol was made according to a known method. 2 -Methyltetrahydrofuran (2-MeTHF, Sigma- Aldrich, >99.0%) and c/.s-cyclooctene (Sigma-Aldrich, 95%) were distilled prior to use. Grubbs 2 ^nd generation catalyst (G2, Sigma- Aldrich) was used as received. Recycled PET, LLDPE, and HDPE materials were used as received. PET and HDPE bottles were cut into pieces for loading into the microcompounder, and LLDPE bags were rolled and inserted whole.

[0052] HOPEOH Synthesis and Characterization. In a 20 mL reaction vessel, c/s-hexadec-6- ene-l,16-diol (see Table 1) and c/.s-cyclooctene (2 g, 18.15 mmol) were dissolved in 2-MeTHF (8 mL). The vessel was sealed with a rubber septum and the solution sparged with argon for 20 min before being heated to 40 °C. A solution of G2 (see Table 1) in 2-MeTHF (400 pL) was added, and the reaction mixture was stirred at 40 °C for 3 h. The viscous solution was diluted with 2-MeTHF (22 mL) and transferred to a pressure reactor. The reactor was sealed and cycled three times with argon from 100 psig to 25 psig while stirring with an overhead stirrer at 100 rpm. The reactor was then charged with 500 psig H2, heated to 100 °C, and stirred at 100 rpm for 20 h. After returning to room temperature, the reactor was depressurized and the chamber flushed with argon. The precipitate that formed was collected via filtration and washed with 2- MeTHF (20 mL) before being dried in a vacuum oven overnight at 60 °C to give the product as a white powder. 'H NMR (500 MHz, toluene-^, 373 K) 8 3.40 (t, -C/LOH), 1.37 (s, -CH ₂ -C# ₂ - CH ₂ -). FTIR Vmax (cm ^-1 ): 2914, 2848, 1472, 1463, 731, 718.

[0053] Nuclear magnetic resonance (NMR) spectroscopy was performed on a Bruker Avance III instrument operating at 500 MHz (toluene-d8, 373 K). Chemical shifts are reported relative to the residual solvent signals. Fourier-transform infrared (FTIR) spectroscopy was carried out using a Bruker Alpha Platinum ATR FT-IR spectrometer with a platinum attenuated total reflectance (ATR) sampling module hosting a diamond crystal. Measurements were carried out in transmittance mode averaged over 64 scans. Size exclusion chromatography (SEC) measurements were performed using an Agilent PL-GPC 220 equipped with three PL-Gel Mixed B columns, integrated RI detector, and Wyatt DAWN HELEOS II LS detector, and the mobile phase was 1,2,4-trichlorobenzene (TCB) containing 0.02 wt% butylated hydroxytoluene as inhibitor at a temperature of 135 °C and flow rate of 1 mL/min. Molecular weight values were calculated from light scattering data using previously reported dn/dc value of -0.097 mL/ for polyethylene in TCB at 135 °C. Samples were prepared at a concentration of 2-4 mg/mL and heated at 135 °C for a minimum of 20 minutes before injection to allow the polymer to dissolve.

Table 1 . Synthesis and Characterization Information for HOPEOH Additives

^Determined by SEC.

[0054] Blend Compounding. Blends were prepared using a DSM Xplore 5cc microcompounder. Before compounding, PET pellets were dried overnight in a vacuum oven at 90°C. Pellets were removed from the oven and immediately transferred to the microcompounder. Before compounding, 4g of PET pellets from the oven were dry mixed with 1g of LLDPE pellets. In neat blends, this mix was fed directly into the microcompounder. For compatibilized blends, a small amount of pellets were added first, followed by the HOPEOH additive, and then the rest of the PET/LLDPE pellets. The blend was then allowed to mix for 5 minutes at 100 RPM. At the end of the mixing time, material was extruded onto reinforced TEFLON paper, and cut into pieces.

[0055] Two staged mixing trials were conducted: one where the HOPEOH additive was first mixed with PET for 5 minutes after which LLDPE pellets were added and mixed for 5 minutes and one where the additive was first mixed into LLDPE and then the resulting mixture used in a blend that was mixed for 5 minutes. It was found that the PET-mixed blends showed a much tighter distribution in strain at break and a decreased droplet size. This is believed to be due at least in part to transport hindering the reaction in the case of the PE-mixed blends.

[0056] Film Pressing. PET/LLDPE blends from the microcompounder were dried overnight at 90°C before pressing into films. Films were compression molded using a Wabash press (Model G15H-12-CLX). To start, a reinforced Teflon sheet was placed on a metal plate along with a 0.2mm rectangular spacer. Material was loaded into the center of these spacers and then covered with another piece of reinforced Teflon and metal plate. This structure was then placed into the hot press and the platens were brought close enough such that both were in contact with the plates. This position was held for 3 minutes, after which the platens were brought into contact at a pressure of 2001b s for 1 minute, after which the pressure was increased to 20001b s for 3 minutes. The film and plates were then transferred to a Carver hot press and cooled at 30°C under 1 OOOlbs of pressure. Films were then removed from the molds and cut into dogbones.

[0057] Mechanical Testing. Samples were cut out using a press and dogbone stencil (ASTM D1708, neck length = 22mm, neck width = 5mm). These dogbones were then tested using an INSTRON 5966 Universal testing system at an extension rate of lOmm/min. At least 8 samples were tested for each set of conditions, and reported values are the average of all samples.

[0058] Domain Size Characterization. A small amount of the extruded filament from the microcompounder and film fragments that were not used for tensile testing were used to characterize domain sizes with atomic force microscopy (AFM). The sample surfaces were polished at -120°C using a Leica U6 Ultramicrotome equipped with glass knives. Samples were allowed to sit on the microtome stage for 15 minutes before being polished.

[0059] AFM was carried out on a Bruker Nanoscope V in tapping mode, stabilized in the repulsive regime. Tips (HQ:NSC36/AL BS) were sourced from Mikromasch USA and had a force constant of 2 N/m and resonance frequency of 130 kHz. The AFM data was turned into an image in Gwyddion and subsequently analyzed using Imaged to calculate droplet sizes. Droplet diameter was determined by drawing ovals around a droplet and back calculating a diameter from the area. Reported values and error are the arithmetic average and standard deviation, respectively, of at least 50 measured droplets.

PET/LLDPE Blends

[0060] HOPEOH of varied molecular weights (1, 4, 13, and 20 kg/mol) was synthesized and used as an additive when compounding blends of virgin PET and LLDPE pellets. Blends were comprised 80 wt% PET and 20 wt% LLDPE, and the HOPEOH loading is reported as a weight ratio of this total mass (e.g., a blend with 4 g of PET pellets, 1 g of LLDPE pellets, and 0.025 g of HOPEOH is reported as 0.5 wt% HOPEOH). After compounding, blends were subsequently pressed into films and tested as described above.

[0061] The HOPEOH additives were found to enhance the mechanical properties of blends, even at low loadings. Representative stress-strain data for blends containing 0.5 wt% HOPEOH are shown in FIG. 2A. Blends containing HOPEOH additives at this loading exhibit similar values for modulus, yield stress, and strain at break (Table 2) despite having quite different molecular weights The compatibilized blends exhibit improved strain at break (SAB or £b) compared to the uncompatibilized blends. Moreover, the SAB values for blends containing these additives at a loading of 0.5 wt% blends or higher are comparable to that of the PET homopolymer (FIG. 2B). At lower loadings (0.2 wt%), the average SAB value decreases, and the uncertainty in the measurements increases. However, these decreased values remain somewhere between neat blend and PET homopolymer, indicating that some level of compatibilization has occurred.

Table 2. Mechanical properties of homopolymers and blends

[0062] To further understand the effects of HOPEOH additives on compatibilization, blend morphologies were studied through scanning electron microscopy (SEM). The blends were cryofractured and imaged at three stages throughout the process: (i) following extrusion from the microcompounder (“as-mixed”), (ii) after being pressed into films (“annealed”), and (iii) after tensile testing (“tested”). Micrographs at all stages for neat blends and blends compatibilized using 0.5 wt% HOPEOH-4k are shown in FIGS. 3A-3F. Domain sizes for the neat PET/LLDPE blends are larger than those in the compatibilized blends at both the as-mixed and annealed stages of the processes. Moreover, gaps between the LLDPE droplets and the PET matrix are apparent in the neat blends, indicating poor interfacial adhesion between the two phases. This poor adhesion is even more apparent in the tested samples, where the matrix fully pulls away from the droplets with little-to-no droplet deformation. Conversely, images of the tested compatibilized blends show deformation of the LLDPE droplets with the matrix, indicating stress transfer between materials and therefore successful compatibilization. Similar images of the tested samples were obtained for blends containing additives of different molecular weights, showing that all additives were successful in transferring stress between phases.

[0063] To quantify compatibilization, the effect of HOPEOH additives on average dispersed phase particle diameter (d) was evaluated after mixing and after domain coarsening upon static thermal annealing. Particle size distribution data for as mixed (FIG. 4A) and static annealed (FIG. 4B) samples was acquired after microtoming using atomic force microscopy (AFM). Only neat blends and blends containing HOPEOH- Ik and -4k are presented here (blends containing HOPEOH-13k and -20k displayed similar results). In the as-mixed samples, the addition of 0.5 wt% HOPEOH- Ik (d = 1.0 ± 0.2 pm) reduced average particle diameter by more than a factor of three compared to neat blends (d = 3.4 ± 1.1 pm). After static thermal annealing, the neat blend particle size almost doubles with the distribution broadening significantly (d = 6.4 ± 3.8 pm), while the compatibilized blend particle sizes increased less with a more uniform particle size distribution (e.g., HOPEOH-lk at 0.5 wt%, d = 1.8 ± 0.6 pm ). Both the reduction in average particle size and suppression of coarsening (i.e., stabilization) are indications of localization of additive at domain interfaces. Similar effects have been reported for pre-made multiblock copolymers.

[0064] At loadings of 0.5 and 1 wt%, the average droplet diameter for blends (as-mixed and annealed) decreases with decreasing additive molecular weight. This decrease in droplet size may be attributed to the higher concentration of hydroxyl groups for lower- molecular- weight samples, i.e., an equivalent mass of shorter chains will have a higher proportion of reactive chain ends able to participate in transesterification with PET. As the same mass of additive is added to the sample at each loading, blends made with HOPEOH-lk have almost 20x the hydroxyl concentration of those made with HOPEOH-20k. This improvement in compatibilization can be balanced with the synthetic considerations of HOPEOH, which typically requires a larger quantity of chain-transfer agent to produce shorter chains.

[0065] Without wishing to be bound by theory, it is believed that reaction of both end groups and the formation of a PE loop in the triblock architecture may improve additive performance. To test this hypothesis, we compared the performance of HOPE OH additives against monohydroxy analogs (PEOH) with similar molar masses. PEOH additives most likely form diblock copolymer compatibilizers through transesterification of their single hydroxy end with PET homopolymer. Formation of PE-PET-PE triblock copolymers from a single PET chain is possible but unlikely due to the large stoichiometric excess of PET chains. Thus, the proposed diblock copolymers lack the ability to form PE loops near domain interfaces like the PET-PE- PET triblock copolymers formed by HOPEOH additives.

[0066] Comparative blends containing monohydroxy PEOH additives at 1 wt% loading were prepared. Generally, dispersed phase sizes decreased with PEOH-3k (das-mixed= 1.7 ± 0.6 pm, danneaied = 3.0 ± 1.3 pm) or PEOH-17k (das-mixed= 2.8 ± 0.8 pm, danneaied = 5.2 ± 2.3 pm) additives compare to neat blend (d _as -mixed ⁼ 3.4 ± 1.1 pm, danneaied = 6.4 ± 3.8 pm). Similar particle sizes (d _as -mixed ⁼ 1.7 ± 0.6 pm, danneaied = 5.0 ± 2.2 pm) were observed for higher loadings ofPEOH-17k at 2 wt%. These data support that an interfacially active copolymer was formed from the monohydroxy additive during melt mixing.

[0067] Representative tensile stress-strain data for PEOH- and HOPEOH-containing blends at comparable molar mass and total hydroxy group concentration (i.e., HOPEOH loading at half that of PEOH) are shown in FIG. 5 A. Blends made with 1 wt% PEOH additive are brittle (8b = 21 ± 22 % and 48 ± 48 % for PEOH-3k and -17k, respectively) compared to similar HOPEOH- containing counterparts (sb = 330 ± 60 % and 310 ± 40 % for HOPEOH-4k and -13k, respectively). Increasing the loading of PEOH- 17k to 2 wt% (comparable hydroxy concentration to HOPEOH- 13k at 1 wt%) does lead to an increase in Sb albeit with a greater variability (sb = 161 ± 85 %) than in the dihydroxy-containing materials (Sb = 370 ± 20) indicating non-uniform compatibilization. Cross-sectional SEM images of tensile tested PEOH-containing blends (FIGs. 5B and 5C) show poor interfacial adhesion at the PET/LLDPE interface, as evidenced by separation of the matrix from the particles, consistent with the poor bulk mechanical properties. [0068] To show that these additives are viable for use in a commercially available recycling stream, they were tested in blends prepared from post-consumer materials using PET from plastic water bottles and LLDPE from a gusset bag. In addition, this experiment was repeated using HDPE from a milk jug to demonstrate that these additives are suitable for different types of PE. The composition of these materials was confirmed via DSC and their neat mechanical properties determined through the same process as the other materials used. Blends were prepared using the same method as previously mentioned experiments using HOPEOH-13k as the additive for compatibilized blends. Tensile stress for these and the neat blends is shown in

FIG. 6. Mechanical properties for blends of recycled PET and LLDPE are shown in Table 3. As with blends prepared from virgin pellets, compatibilized blends showed improved strain at break compared to the uncompatibilized blends for blends containing either LLDPE or HDPE.

Table 3. Mechanical properties of compatibilized and uncompatibilized recycled blends.

PET/iPP Blends

[0069] Blends of PET and iPP were compatibilized with HOPEEEOH. FIG. 7 shows tensile stress for PET, iPP, a neat 80/20 blend of PET and PP, and a 80/20 blend of PET and iPP compatibilized with 2 wt% HOPEEEOH (batch mix and stage mix). Table 4 lists mechanical properties for these polymers and blends. A modulus decrease is observed for the stage mix relative to the batch mix. FIGS. 8 A and 8B are SEM images of the neat blend, and FIGS. 8C and 8D are SEM images of the batch mixed and stage mixed compatibilized blend, respectively. Comparison of these images shows that the addition of HOPEEEOH decreases droplet size.

Adhesion between the matrix and droplets is not sufficient for droplet deformation.

Table 4. Mechanical properties of polymers and neat and compatibilized blends. [0070] FIG. 9 shows tensile stress for an 80/20 blend of PET and iPP compatibilized with an increased load of 5 wt% HOPEEEOH (stage mix). Table 5 adds the mechanical properties of this blend to data in Table 4. As seen in Table 5, the modulus of this blend decreases, believed to be due at least in part to increased chain scission. FIG. 10 is an SEM image of the resulting blend, showing some deformation of droplets within the matrix.

Table 5. Mechanical properties of polymers and neat and compatibilized blends.

[0071] FIG. 11 shows tensile stress for an 80/20 blend of PET and iPP compatibilized with an increased load of 5 wt% HOPEEEOH with an increased mixing intensity (150 RPM). The resulting blend was found to be uniformly brittle. As seen in Table 6, the modulus of this blend decreases, believed to be due at least in part to increased chain scission.

Table 6. Mechanical properties of polymers and neat and compatibilized blends.

^Materials with comparable crystallinity [0072] Table 7 lists additive molecular weight (MW) and homopolymer entanglement molecular weight (Me) for the PE and iPP systems. For blends with iPP, additive MW « Me. Table 7

Entanglement

Molecular Weight

Polymer Molecular Weight of Additive (g/mol) Me (g/mol)

Polyethylene 1,000 20,000 828 isotactic

3.000 6,900

Polypropylene

[0073] Although the disclosed inventive concepts include those defined in the attached claims, it should be understood that the inventive concepts can also be defined in accordance with the following embodiments.

[0074] In addition to the embodiments of the attached claims and the embodiments described above, the following numbered embodiments are also innovative.

[0075] Embodiment 1 is a method of making a polymer composite, the method comprising: combining polyethylene terephthalate, polyolefin, and a hydroxy telechelic polyolefin additive to yield a mixture; compounding the mixture to yield a blend comprising a polyethylene terephthalate homopolymer, a polyolefin homopolymer, and a copolymer comprising a reaction product of the hydroxy telechelic polyolefin and the polyethylene terephthalate; and extruding the blend to yield the polymer composite.

[0076] Embodiment 2 is the method of embodiment 1, wherein the polyolefin comprises polyethylene.

[0077] Embodiment 3 is the method of embodiment 2, wherein the polyethylene comprises LLDPE, HDPE, or a combination thereof.

[0078] Embodiment 4 is the method of embodiment 1, wherein the polyolefin comprises polypropylene.

[0079] Embodiment 5 is the method of embodiment 4, wherein the polypropylene comprises isotactic polypropylene. [0080] Embodiment 6 is the method of any one of embodiments 1-5, wherein the hydroxy telechelic polyolefin additive is synthesized by a ring-opening metathesis polymerization of cyclooctene followed by catalytic hydrogenation.

[0081] Embodiment 7 is the method of any one of embodiments 1-5, wherein the hydroxy telechelic polyolefin additive is synthesized by an anionic polymerization of butadiene followed by catalytic hydrogenation.

[0082] Embodiment 8 is the method of any one of embodiments 1-7, wherein the hydroxy telechelic polyolefin additive comprises HOPEOH or HOPEEEOH.

[0083] Embodiment 9 is the method of any one of embodiments 1-8, wherein the mixture comprises 5 wt% or less of the hydroxy telechelic polyolefin additive.

[0084] Embodiment 10 is the method of embodiment 9, wherein the mixture comprises 1 wt% or less of the hydroxy telechelic polyolefin additive.

[0085] Embodiment 11 is the method of any one of embodiments 1-10, wherein a molecular weight of the hydroxy telechelic polyolefin additive is in a range of Ik to 25k g/mol.

[0086] Embodiment 12 is the method of any one of embodiments 1-11, wherein the polyethylene terephthalate and polyolefin are post-consumer plastics.

[0087] Embodiment 13 is the method of any one of embodiments 1-12, wherein the hydroxy telechelic polyolefin additive is combined with at least some of the polyethylene terephthalate to yield a precursor, and the polyolefin is combined with the precursor to yield the mixture.

[0088] Embodiment 14 is the method of any one of embodiments 1-13, wherein the polyolefin comprises two or more different polyolefins.

[0089] Embodiment 15 is the method of embodiment 14, wherein the two or more different polyolefins comprise PE and iPP.

[0090] Embodiment 16 is the method of any one of embodiments 1-15, wherein the mixture comprises an additional polymer.

[0091] Embodiment 17 is the method of embodiment 16, wherein the additional polymer comprises nylon.

[0092] Embodiment 18 is a copolymer comprising: a polyethylene terephthalate block; and a polyolefin block, wherein the copolymer is a reaction product of a polyethylene terephthalate homopolymer and a hydroxy telechelic polyolefin additive.

[0093] Embodiment 19 is the copolymer of embodiment 18, wherein the copolymer is a multiblock copolymer having formula [polyethylene terephthalate]-[polyolefin]-[polyethylene terephthalate],

[0094] Embodiment 20 is the copolymer of embodiment 1 or 2, wherein the polyolefin comprises polyethylene.

[0095] Embodiment 21 is the copolymer of embodiment 20, wherein the polyethylene comprises LLDPE, HDPE, or a combination thereof.

[0096] Embodiment 22 is the copolymer of any one of embodiments 18-21, wherein the polyolefin comprises polypropylene.

[0097] Embodiment 23 is the copolymer of embodiment 22, wherein the polypropylene comprises isotactic polypropylene.

[0098] Embodiment 24 is the copolymer of any one of embodiments 18-23, wherein the hydroxy telechelic polyolefin additive comprises HOPEOH or HOPEEEOH.

[0099] Embodiment 25 is the copolymer of any one of embodiments 18-24, wherein a molecular weight of the hydroxy telechelic polyolefin additive is in a range of Ik to 25k g/mol. [00100] Embodiment 26 is the copolymer of any one of embodiments 18-25, wherein the polyethylene terephthalate is a post-consumer plastic.

[00101] Embodiment 27 is the copolymer of any one of embodiments 18-26, further comprising an additional polyolefin block.

[00102] Embodiment 28 is the copolymer of embodiment 27, wherein the polyolefin block comprises PE and the additional polyolefin block comprises iPP.

[00103] Embodiment 29 is the copolymer of any one of embodiments 18-28, further comprising an additional polymer block.

[00104] Embodiment 30 is the copolymer of embodiment 29, wherein the additional polymer block comprises nylon.

[00105] Embodiment 31 is a polymer composite formed by the method of any one of embodiments 1-17.

[00106] Embodiment 32 is a polymer composite comprising: polyethylene terephthalate; polyolefin; and the copolymer of any one of embodiments 18-30.

[00107] Embodiment 33 is the polymer of embodiment 32, wherein the polyolefin comprises two or more different polyolefins.

[00108] Embodiment 34 is the polymer of embodiment 32 or 33, further comprising an additional polymer.

[00109] Embodiment 35 is a polymer composite comprising: post-consumer polyethylene terephthalate; post-consumer polyolefin; and a copolymer comprising a reaction product of the hydroxy telechelic polyolefin and the post-consumer polyethylene terephthalate.

[001 10] Embodiment 36 is the polymer composite of embodiment 35, wherein the copolymer is formed in situ.

[00111] Embodiment 37 is the polymer composite of embodiment 35 or 36, wherein the postconsumer polyolefin comprises two or more polyolefins.

[00112] Embodiment 38 is the polymer composite of embodiment 37, wherein the two or more polyolefins comprise PE and iPP.

[00113] Embodiment 38 is the polymer composite of any one of embodiments 35-38, further comprising an additional polymer.

[00114] Embodiment 39 is the polymer composite of embodiment 38, wherein the additional polymer comprises nylon.

[00115] Although this disclosure contains many specific embodiment details, these should not be construed as limitations on the scope of the subject matter or on the scope of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in this disclosure in the context of separate embodiments can also be implemented, in combination, in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments, separately, or in any suitable sub-combination. Moreover, although previously described features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can, in some cases, be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

[00116] Particular embodiments of the subject matter have been described. Other embodiments, alterations, and permutations of the described embodiments are within the scope of the following claims as will be apparent to those skilled in the art. While operations are depicted in the drawings or claims in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed (some operations may be considered optional), to achieve desirable results.

[00117] Accordingly, the previously described example embodiments do not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure.