Patent Application
20240199871
The present application relates to thermoplastic graft copolymers including acrylated epoxidized vegetable oils.
In the thermoplastic and thermoplastic elastomer industry, various styrenic and diene-based polymers have been used for nearly endless applications. Polymers such as acrylonitrile-butadiene-styrene terpolymer (ABS) and styrene-b-butadiene-b-styrene (SBS) block copolymer are widely used for their mechanical performance and ability to be extruded. While these polymers display excellent processability and mechanical performance, the volatile price of butadiene, along with its non-renewable nature, has caused an extensive amount of time and resources to be dedicated to reducing the dependence on non-renewable feedstocks. Alternative sources for polymers or their feedstocks, such as renewable natural resources, could provide a sustainable source for the plastic industry. Renewable resources can vary from materials derived from trees and plants to synthetically altered sugars, fats, oils, and proteins. Polymers derived from these various biological sources can produce various materials that have properties ranging from elastomeric to rigid. Biopolymers possess the potential to be more environmentally friendly and more economically stable than their petroleum counterparts. Biopolymers need to assimilate the properties of petroleum-based polymers using an abundant, low-cost commodity feedstock that enables an economical pathway to commercialize a high value or volume application.
Concerns over green-house gas emissions caused by nondegradable, petroleum-derived engineering thermoplastics has recently caused a drive for more sustainable alternatives (Hottle et al., Waste Management 38:86-94 (2015); A. J. J. Straathof, Chem. Rev. 114:1871-1908 (2014)). Polylactide (PLA) has recently been shown to be a successful example of a bio-derived degradable polyester, by both commercial volume and overall production cost (Zhang et al., ACS Appl. Mater. Interfaces 6:12436-12448 (2014)). Although PLA contains a high tensile strength and elastic modulus, pristine PLA is brittle and prevents further developments in applications requiring ductility and impact resistance (Xu et al., Macromolecules 50:6421-6432 (2017)). Since PLA shares many limitations with other commodity thermoplastics, similar strategies have been used to alter the mechanical properties of various petroleum based thermoplastics such as polystyrene (PS) and poly butylene terephalate (PBT). Many of these techniques include copolymerization (Grijpma and Pennings, Macromol. Chem. Phys. 195:1649-1663 (1994); Hiljanen-Vainio et al., J. Appl. Polym. Sci. 59:1281-1288 (1996)), plasticization (Liu et al., Polymer 148:109-118 (2018); Mauck et al., Macromolecules 49:1605-1615 (2016)), extrusion with flexible polymers (Wang et al., Polym. Eng. Sci. 49:26-33 (2009); Meng et al., Mater. Des. 139:188-197 (2018)), and dynamic vulcanization (Zhao et al., ACS Sustain. Chem. Eng. 5:1938-1947 (2017); Liu et al., Macromolecules 43:6058-6066 (2010)).
Copolymers of lactide with other cyclic monomers, such as poly caprolactone (PCL), can be used to generate statistical or block copolymers with exact mechanical property profiles; however, many of these copolymers are prohibitively expensive for use as single use plastics, and are solely used in low volume high value applications (Jing and Hillmyer, J. Am. Chem. Soc. 130:13826-13827 (2008); Theryo et al., Macromolecules 43:7394-7397 (2010)). Dynamic vulcanization has proven to be an effective way to enhance the toughness of PLA but crosslinking can cause issues with reprocessing the material as the matrix transitions from a thermoplastic to a thermoset (He et al., RSC Adv. 4:12857-12866 (2014)). Designing a low cost high volume toughened PLA thermoplastic resides in synthesizing polymer blends. This is similar to how Acrylonitrile-co-Styrene (SAN) matrix is toughened with butadiene micelles to synthesize acrylonitrile-butadiene-styrene (ABS). A limitation of polymer-polymer blends is the immiscibility caused by the interfacial energy between the matrix and dispersed phases (Gramlich et al., Macromolecules 43:2313-2321 (2010); Xue et al., Polymers 10:1401 (2018)). Compatibilizers are used to stabilize the interface to form stable blends. Reactive extrusion has been used to generate graft copolymers between the matrix and the dispersed polymer and has been shown to provide a highly toughened PLA at loadings <20% (Wang et al., Polymer 92:74-83 (2016); Wang et al., Eur. Polym. J. 85:92-104 (2016); Liu et al., Macromolecules 43:6058-6066 (2010)). Block copolymers have also been used as a compatibilzer with PLA where one block is matrix miscible and another is matrix immiscible (Li et al., ACS Macro Letters 5:359-364 (2016); Liu et al., Macromolecules 43:7238-7243 (2010)). These block copolymers can be dispersed throughout the thermoplastic matrix at the nano scale and can significantly toughen PLA with loadings (>5%). While both of these strategies can toughen PLA at small loadings, these impact modifiers are still petroleum based.
The present application is directed to overcoming these and other limitations in the art.
The present application relates to thermoplastic graft copolymer including: one or more thermoplastic polymers of formula I:
and
where:
A second aspect of the present application relates to thermoplastic polymeric mixture including:
and
A third aspect of the present application relates to a method of forming a thermoplastic graft copolymer. The method includes:
with a branched chain thermoplastic polymer of formula II:
where
Polylactide is a compostable bioderived polyester that has gained popularity as a replacement for petroleum based thermoplastics. Engineering thermoplastics are used in applications requiring high impact strength and ductility. While petroleum based thermoplastics fit this criteria, PLA is brittle and unsuitable for these uses. Advances in toughening PLA can be seen using polymer blends where a reactive impact modifier is used to concentrate the stress at low Tg rubbers and dissipate the energy. The majority of these impact modifiers however are petroleum based and not bioderived. This application shows that PLA can be significantly enhanced with the addition of a bioderived reactive soybean based elastomer. As little as 10 wt % poly(acrylated epoxidized high oleic soybean oil) (PAHOESO) derivatives can exhibit tensile toughness and notched Izod impact strength over an order of magnitude higher than pristine PLA with only minute reductions in the elastic modulus. A series of PLA blends containing PAHOESO based polymers were synthesized at varying molecular weights, polymer loadings, and polymer architectures. The toughness was shown to increase as the morphology changed from spherical to rod-like. Using TEM, the largest degree of toughening is observed when small rod-like micelles are formed and well dispersed throughout the PLA matrix. This new series of biobased polymers along with the facilitation of compatibilized micelles suggest a cost-effective strategy for toughening brittle thermoplastics with bioderived polymers.
The present application relates to thermoplastic graft copolymer including: one or more thermoplastic polymers of formula I:
and
where:
As used herein the term “biodegradable” refers to materials that are capable of being broken down especially into innocuous products by the action of living things.
The term “copolymer” refers to a polymer derived from more than one species of monomer.
As used herein “graft copolymers” are copolymers having a main chain and one or more side chains that are constitutionally different from the main chain. Typically, the graft copolymers of the present invention contain main and side chains that are constitutionally different from one another, because they are derived from different characteristic species of monomer (e.g., because a monomer found in the main chain is not found in the side chains and/or vice versa).
The term “statistically defined manner” refers to the repeat unit sequence distribution (RUSD) of the polymer, which is determined by the polymerization chemistry, the number and nature of comonomers, and the reaction conditions under which the polymer is formed. For any polymer, the RUSD can be represented by a probability function Pi(j) that indicates the likelihood that the identity of the repeat unit at location j along the chain contour is i. Common RUSD classifications include, but are not limited to, random (Pi=constant) and block (e.g., Pi(j<f)=0 and Pi(j≥f)=1 given fixed contour coordinate f). RUSD prediction and measurement are discussed in most polymer chemistry texts, e.g., Hiemenz and Lodge, Polymer Chemistry, 2nd Ed., Boca Raton Fl. CRC Press (2007), which is hereby incorporated by reference in its entirety.
The term “block copolymer” or “block polymer” refers to a macromolecule consisting of long sequences of different repeat units. Exemplary block polymers include, but are not limited to AnBm, AnBmAk, AnBmCk, or AnBmCkAn, wherein A, B, and C represent the different monomers, and n, m, and k are the number of monomers present in each block.
The term “glass transition temperature” or “Tg” refers to the temperature at which a polymeric material transitions from a glassy state (e.g., brittleness, stiffness, and rigidity) to a rubbery state (e.g., flexible and elastomeric). The Tg can be determined, for example, using techniques such as Differential Scanning Calorimetry (DSC) or Dynamic Mechanical Analysis (DMA).
As used herein, the term “thermoplastic” refers to polymeric material that flows when heated and then returns to its original state when cooled to room temperature. However, under some conditions (e.g., applications where solvent resistance or higher temperature performance is desired), the thermoplastic polymers can be covalently crosslinked. Upon crosslinking, the materials lose their thermoplastic characteristics and become thermoset materials.
As used herein, the term “thermoset” refers to polymeric materials that become infusible and insoluble upon heating and that do not return to their original chemical state upon cooling. Thermoset materials tend to be insoluble and resistant to flow.
As used herein, the term “engineering thermoplastics” refers to a group of polymers that possess a balance of properties comprising strength, stiffness, impact resistance, and long term dimensional stability that make them useful as structural materials.
In some embodiments of the present application the thermoplastic polymer of formula (I) is a copolymer or terpolymer. Exemplary polymers useful as the thermoplastic polymer of formula (I) include, but are not limited to, polylactide, poly butylene succinate, poly hydroxyalkanoates, polyethylene terephthalate, poly butylene terephthalate, polypropylene furanoate, polyethylene furanoate, and combinations thereof.
As used herein the term “polylactic acid”, or “polylactide” (PLA) includes poly(D-lactide), poly(L-lactide), poly(DL-lactide), and combinations thereof. PLA in general has a formula of:
PLAs are polymers produced by the ring opening polymerization of lactide or the polycondensation of lactic acid, which is typically derived from a starch from corn or potatoes.
The polylactic acid may be formed by known methods, such as dehydration condensation of lactic acid (see, U.S. Pat. No. 5,310,865 to Enomoto et al., which is hereby incorporated by reference in its entirety) or synthesis of a cyclic lactide from lactic acid followed by ring opening polymerization of the cyclic lactide (see, U.S. Pat. No. 2,758,987 to Ito et al., which is hereby incorporated by reference in its entirety), for example. Such processes may utilize catalysts for polylactic acid formation, such as tin compounds (e.g., tin octylate), titanium compounds (e.g., tetraisopropyl titanate), zirconium compounds (e.g., zirconium isopropoxide), antimony compounds (e.g., antimony trioxide), or combinations thereof, for example.
Poly(hydroxyalkanoates) (PHAs) are well-known polyester compounds produced by a variety of microorganisms, such as bacteria and algae. A PHA polyester can include the same or different repeating units, depending upon the choice of carbon source substrates and fermentation conditions employed in the production of the PHA.
The poly(hydroxyalkanoates) used in the present application may be obtained from a biological source or from a chemical synthesis. The biological source can be a microorganism, a higher organism such as a plant, or a genetically modified bioreactor such as a host cell that can be a prokaryote or a eukaryote. Methods used to produce PHAs biologically are known in the art such as, for example, those methods discussed in U.S. Pat. No. 4,910,145 to Holmes et al.; and U.S. Pat. Nos. 5,245,023; 5,250,430; 5,480,794; 5,512,669; and 5,534,432 to Peoples et al., which are hereby incorporated by reference in their entirety. Methods of producing PHAs through chemical synthesis include, but are not limited to, ring-opening polymerization of β-lactone monomers and condensation polymerization of esters of β-hydroxy alkanioc acids, each of which are discussed in U.S. Pat. No. 6,610,764 to Martin et al., and U.S. Pat. No. 5,563,239 to Hubbs et al., respectively, which are hereby incorporated by reference in their entirety. Poly(hydroxyalkanoates) generally are formed from hydroxyacid monomeric units or derivatives thereof. These include, for example, polylactic acid, polyhydroxybutyrate, polyhydroxyvalerate, polycaprolactone and the like.
Suitable poly(hydroxyalkanoates) may be represented by the formula:
where each occurrence of R in the polymer chain is independently selected from an alkyl moiety that may be linear or branched, having from 1 to 20 carbon atoms, for example from 1 to 12 carbon atoms; and n is an integer such that the ester is polymeric (e.g., n can range from 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 to 100,000). The poly(hydroxyalkanoates) may be R-poly(hydroxyalkonates), S-poly(hydroxyalkonates), or a combination thereof.
Useful poly(hydroxyalkanoates) include, for example, homo- and copolymers of poly(3-hydroxybutyrate), poly(4-hydroxybutyrate), poly(3-hydroxyvalerate), poly(lactic acid) (also known as polylactide), poly(3-hydroxypropanoate), poly(4-hydropentanoate), poly(3-hydroxypentanoate), poly(3-hydroxyhexanoate), poly(3-hydroxyheptanoate), poly(3-hydroxyoctanoate), polydioxanone, polycaprolactone, and polyglycolic acid (i.e. polyglycolide). Copolymers of two or more of the above hydroxy acids may also be used, for example, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(lactate-co-3-hydroxypropanoate), poly(glycolide-co-p-dioxanone), and poly(lactic acid-co-glycolic acid). Blends of two or more of the poly(hydroxyalkanoates) may also be used.
Polybutylene succinate (PBS) is a biodegradable aliphatic polyester that consists of polymerized units of butylene succinate, with repeating C8H12O4 units shown below:
Under natural conditions, PBS can be decomposed by various microorganisms or enzymes to form carbon dioxide and water. PBS has good ductility, elongation at break, heat resistance and impact resistance.
Commodities such as soybeans provide an abundant, low-cost option as an alternative feedstock for petroleum-based polymers. Soybean oil-based polymers can provide a wide range of characteristics ranging from soft and elastic to hard and rigid depending on the monomer used. Soybean oil-based monomers are unique due to their variable saturation composition, which enables them to be multi-functional. These multi-functional chemical moieties allow soybean polymers to have acrylic, alcohol, ester, and epoxy functionality, which can be exploited using reactive extrusion with various polyester or polydiene polymers.
Soybean Oil (SBO) is the most abundant vegetable oil, which accounts for almost 30% of the world's vegetable oil supply. SBO is particularly suitable for polymerization, because it possesses multiple carbon-carbon double bonds that allow for modifications such as conjugation of the double bonds, etc.
Vegetable oils and animal fats are mixtures of triglycerides. A representative structure of a triglyceride is shown as below:
A typical triglyceride structure contains a number of double bonds that may serve as candidates for polymerization. Various soybean cultivars express a variety of triglyceride compositions in their oils. Different strains of soybeans may be appropriately selected based on the triglyceride compositions to enhance the block copolymer yield and properties.
Renewable source-derived fats and oils comprise glycerol triesters of fatty acids. These are commonly referred to as “triglycerides” or “triacylglycerols” (TAG). Fats and oils are usually denoted by their biological source and contain several different fatty acids typical for each source. For example, the predominant fatty acids of soybean oil are the unsaturated fatty acids oleic acid, linoleic acid, and linolenic acid, and the saturated fatty acids palmitic acid and stearic acid. Other fatty acids are present at low levels. Triglycerides are the main component of natural oils and are composed of three fatty acids groups connected by a glycerol center.
“Triglycerides,” as defined herein, may refer to any unmodified triglycerides naturally existent in plant oil or animal oil or animal fat as well as any derivatives of unmodified triglycerides, such as synthetically derived triglycerides. The naturally existent parent oil may also contain derivatives of triglycerides, such as free fatty acids. An unmodified triglyceride may include any ester derived from glycerol with three similar or different fatty acids. Triglyceride derivatives may include any modified triglycerides that contain conjugated systems (i.e. a system of connected p-orbitals with delocalized electrons in triglycerides). Such conjugated systems increase the reactivity of triglycerides towards propagation reactions. Useful conjugated triglycerides include, but are not limited to, triglyceride derivatives containing conjugated double bonds or conjugated systems formed by acrylate groups.
Unsaturated fatty acids are susceptible to epoxidation to form fatty acids bearing epoxide rings. Thus, triglycerides containing unsaturated fatty acids can be subjected to epoxidation to form epoxidized triglycerides in which one, two, or all three fatty acids bear at least one epoxide ring. Diglycerides (diacylglycerols, “DAG”) can be obtained when one fatty acid is removed from a triglyceride, typically by hydrolysis; monoglycerides (monoacylglycerols, “MAG”) may be obtained when two fatty acids are removed from a triglyceride.
The term “epoxide” or “oxirane” includes an epoxide ring (i.e., group) as shown below:
Epoxidized triglycerides can be found as such in nature, for instance in Vernonia plants, or can be conveniently synthesized from more common unsaturated oils by using a standard epoxidation process. See U.S. Patent Publ. No. 20120156484 to Vendamme et al., which is hereby incorporated by reference in its entirety.
The compounds described herein may contain one or more epoxide (oxirane) rings, and, unless specified otherwise, it is intended that the compounds include both cis- or trans-isomers and mixtures thereof. When the compounds described herein contain olefinic double bonds or other centers of geometric asymmetry, and, unless specified otherwise, it is intended that the compounds include both E and Z geometric isomers.
The oxirane oxygen content (also referred to herein as % oxirane oxygen or wt % of oxirane) of may be determined by using Official Method, Standard Cd 9-57 of the American Oil Chemists' Society (“Oxirane Oxygen in Epoxidized Materials” Official Method Cd 9-57 by the American Oil Chemist' Society (Reapproved 2017), which is hereby incorporated by reference in its entirety).
For example, oxirane oxygen content for epoxidized soybean oil may be about 7.2% and for sub-epoxidized soybean oil may be about 4.5%. The functionality is the number of epoxide groups per molecule. The functionality of epoxidized soybean oil in accordance with the present application may be approximately 4.5 and sub-epoxidized soybean oil may be approximately 2.1. The sub-epoxidized soybean oil in accordance with the present application may contain between 0.1 wt % and 10 wt % of oxirane. For example, the wt % of oxirane may be about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 wt %.
The thermoplastic polymer of formula (II) according to the present application may be formed from a fully or partially epoxidized TAG, which means that at least one of the double bonds of the unsaturated fatty acid ester in the precursor is oxidized to an epoxy group. Such oxidations are well known in the art and can be readily accomplished in an industrial scale, e.g., by using hydrogen peroxide and a carboxylic acid (e.g., formate or acetate), or by the halohydrin method. See WO 2007062158 to Selifonov, which is hereby incorporated by reference in its entirety.
Epoxidized triglycerides are commercially available. See U.S. Patent Publ. No. 20120156484 to Vendamme et al., which is hereby incorporated by reference in its entirety. For example, epoxidized linseed oil (ELO) is available from Cognis (Düsseldorf, Germany) under the trade name DEHYSOL B316 SPEZIAL, or Arkema (King of Prussia, Pa.) under the trade name VIKOFLEX 7190. An exemplary structure of an epoxidized triglyceride of linseed oil is as follows:
The epoxidized precursor triglycerides for forming compounds of formula (II) can be subjected to esterification reactions with polyhydric alcohols (such as sugars, sugar acids, glycerol, and glycols) to form epoxidized esters of polyols, or with monohydric alcohols (such as benzyl alcohol, methanol, ethanol, propanols, butanols, and longer alcohols), furan-containing alcohols (such as tetrahydro-2-furanmethanol and 2-furanmethanol), glycidol, and fusel oil) to form epoxidized monoesters. Alternatively, epoxidized esters of polyols or of monohydric alcohols can be obtained by subjecting the esters to epoxidation.
Renewable source derived fats and oils include algal oil, animal fat, beef tallow, borneo tallow, butterfat, camelina oil, candlefish oil, canola oil, castor oil, cocoa butter, cocoa butter substitutes, coconut oil, cod-liver oil, colza oil, coriander oil, corn oil, cottonseed oil, false flax oil, flax oil, float grease from wastewater treatment facilities, hazelnut oil, hempseed oil, herring oil, illipe fat, jatropha oil, kokum butter, lanolin, lard, linseed oil, mango kernel oil, marine oil, meadowfoam oil, menhaden oil, microbial oil, milk fat, mowrah fat, mustard oil, mutton tallow, neat's foot oil, olive oil, orange roughy oil, palm oil, palm kernel oil, palm kernel olein, palm kernel stearin, palm olein, palm stearin, peanut oil, phulwara butter, pile herd oil, pork lard, radish oil, ramtil oil, rapeseed oil, rice bran oil, safflower oil, sal fat, salicornia oil, sardine oil, sasanqua oil, sesame oil, shea fat, shea butter, soybean oil, sunflower seed oil, tall oil, tallow, tigernut oil, tsubaki oil, tung oil, triacylglycerols, triolein, used cooking oil, vegetable oil, walnut oil, whale oil, white grease, yellow grease, and derivatives, conjugated derivatives, genetically-modified derivatives, and mixtures of any thereof. In one embodiment, the thermoplastic polymers of formula (II) may be derived from sources selected from the group consisting of fish oil, animal oil, vegetable oil, synthetic and genetically-modified plant oils, and mixtures thereof. Examples of vegetable oil include rapeseed oil, safflower oil, canola oil, castor oil, sunflower oil, linseed oil, soybean oil, and corn oil.
These triglycerides or triglyceride mixtures are typically plant oils. Suitable plant oils useful for the triacyl glyceride of the (meth)acrylated epoxidized triacyl glyceride of the branched chain thermoplastic polymer of formula II include, but are not limited to, a variety of vegetable oils such as soybean oil, peanut oil, walnut oil, palm oil, palm kernel oil, sesame oil, sunflower oil, safflower oil, rapeseed oil, linseed oil, flax seed oil, colza oil, coconut oil, corn oil, cottonseed oil, olive oil, castor oil, false flax oil, hemp oil, mustard oil, radish oil, ramtil oil, rice bran oil, salicornia oil, tigernut oil, tung oil, etc., and mixtures thereof. Typical vegetable oils used herein includes soybean oil, linseed oil, corn oil, flax seed oil, or rapeseed oil.
The poly(acrylated epoxidized high oleic soybean oil) (PAEHOSO) used in the exemplary copolymers of the present application may be formed using controlled radical polymerization (also known as living polymerization) of acrylated epoxidized high oleic soybean oil. Exemplary controlled free radical polymerization reactions that can be used for the formation of the thermoplastic polymers of formula (II) include atom transfer radical polymerization (ATRP) or reversible addition-fragmentation chain transfer (RAFT) polymerization. Examples of RAFT polymerization methods useful for forming the thermoplastic polymers of formula (II) can be found in U.S. Pat. No. 9,650,463 to Cochran et al., which is hereby incorporated by reference in its entirety. Examples of ATRP polymerization methods useful for forming the thermoplastic polymers of formula (II) can be found in U.S. Pat. No. 9,932,435 to Cochran et al., which is hereby incorporated by reference in its entirety.
In some embodiments of the present application the thermoplastic polymer of formula II has at least one occurrence of R4′ selected from a thioester or carbonotrithioate.
In some embodiments of the present application, the thermoplastic polymer of formula II has a number average molecular weight ranging from 10 kDa to 1000 kDa. For example, the molecular weight may range from 10 kDa, 50 kDa, 100 kDa, 150 kDa, 200 kDa, 250 kDa, 300 kDa, 350 kDa, 400 kDa, 450 kDa, 500 kDa, 550 kDa, 600 kDa, 650 kDa, 700 kDa, 750 kDa, 800 kDa, 850 kDa, 900 kDa, or 950 kDa to 100 kDa, 150 kDa, 200 kDa, 250 kDa, 300 kDa, 350 kDa, 400 kDa, 450 kDa, 500 kDa, 550 kDa, 600 kDa, 650 kDa, 700 kDa, 750 kDa, 800 kDa, 850 kDa, 900 kDa, or 950 kDa up to 50 kDa, 100 kDa, 150 kDa, 200 kDa, 250 kDa, 300 kDa, 350 kDa, 400 kDa, 450 kDa, 500 kDa, 550 kDa, 600 kDa, 650 kDa, 700 kDa, 750 kDa, 800 kDa, 850 kDa, 900 kDa, or 950 kDa to 100 kDa, 150 kDa, 200 kDa, 250 kDa, 300 kDa, 350 kDa, 400 kDa, 450 kDa, 500 kDa, 550 kDa, 600 kDa, 650 kDa, 700 kDa, 750 kDa, 800 kDa, 850 kDa, 900 kDa, 950 kDa or 1000 kDa.
A second aspect of the present application relates a to thermoplastic polymeric mixture including:
and
In some embodiments of the present application, the thermoplastic graft copolymer forms as micelles between the thermoplastic polymers of formula I and the thermoplastic polymer of formula II. The micelles may range in diameter from 5 nm to 2000 nm. The micelles act as compatibilizers between the bulk of the thermoplastic polymer of formula (I) and the thermoplastic polymer of formula (II).
Much like small molecule surfactants that reduce the energy of the oil/water interface to yield emulsions, heterogeneous copolymers like block or graft copolymers contain two or more thermodynamically distinct repeat unit sequences. In the simplest case of an AB diblock copolymer, the “A” component is thermodynamically miscible with A-like polymers whereas the “B” component is compatible with B-like copolymers. In A+B+AB mixtures, the Gibbs energy of the mixture is often minimized when spherical droplets of “B” are dispersed throughout an “A” matrix, with the AB copolymers localizing in the A/B interphase region to minimize the interfacial energy. A book chapter by Gohy provides a thorough review of these phenomena (Gohy, Jean-François. “Block Copolymer Micelles,” Block Copolymers II, Springer, Berlin, Heidelberg, p 65-136 (2005), which is hereby incorporated by reference in its entirety). In the present application, the graft copolymers play an analogous role to promote the dispersion of polymers of formula (II) throughout the polymer of formula (I) matrix.
The thermoplastic polymeric mixture of the present application may further contain a plasticizer. Primary plasticizers have been reported where the plasticizers contain fatty acids derived from vegetable oils and the fatty acids are substantially fully esterified with an alcohol (monool or polyol), the fatty acids have unsaturated bonds that are substantially fully epoxidized, and the fatty acids are added substantially randomly to one or more hydroxyl sites on the alcohol. See U.S. Pat. No. 6,797,753 to Benecke et al, which is hereby incorporated by reference in its entirety. Primary plasticizers include, but are not limited to, epoxidized pentaerythritol tetrasoyate, epoxidized propylene glycol disoyate, epoxidized ethylene glycol disoyate, epoxidized methyl soyate, epoxidized sucrose octasoyate, and the epoxidized product of soybean oil interesterified with linseed oil. For example, subepoxidized soybean oil may act as a plasticizer to the copolymers of the present application.
In some embodiments of the polymeric mixture of the present application, the ratio of thermoplastic polymers of formula I and the thermoplastic polymer of formula II ranges from 1 wt % to 99 wt %.
The thermoplastic polymeric mixture has an increased tensile toughness when compared to the thermoplastic polymer of formula (I) on its own. For example, the tensile toughness may range from 2 to 200 times the toughness of the thermoplastic polymer of formula I without the branched chain thermoplastic polymer of formula II.
The thermoplastic polymeric mixture may be used in an elastomeric composition. The elastomeric compositions may be vulcanized, cross-linked, compatibilized, and/or compounded with one or more other elastomer, additive, modifier, and/or filler.
The thermoplastic polymeric mixture may be used in an adhesive composition including a tackifier and/or a plasticizer blended with the thermoplastic polymeric mixture.
The thermoplastic polymeric mixture may be used in a toughened engineering thermoplastic composition. The engineering thermoplastic polymers of the present application may be formed into a wide variety of articles such as films, pipes, fibers (e.g., dyeable fibers), rods, containers, bags, packaging materials, and adhesives (e.g., hot melt adhesives) for example, by polymer processing techniques known to one of skill in the art, such as forming operations including film, sheet, pipe, and fiber extrusion and co-extrusion as well as blow molding, injection molding, rotary molding, and thermoforming, for example. Films include blown, oriented, or cast films formed by extrusion or co-extrusion or by lamination useful as shrink film, cling film, stretch film, sealing films, oriented films, snack packaging, heavy duty bags, grocery sacks, baked and frozen food packaging, medical packaging, industrial liners, and membranes, for example, in food-contact and non-food contact application. Fibers include slit-films, monofilaments, melt spinning, solution spinning, and melt blown fiber operations for use in woven or non-woven form to make sacks, bags, rope, twine, carpet backing, carpet yarns, filters, diaper fabrics, medical garments, and geotextiles, for example. Extruded articles include medical tubing, wire and cable coatings, hot melt adhesives, sheets, such as thermoformed sheets (including profiles and plastic corrugated cardboard), geomembranes, and pond liners, for example. Molded articles include single and multilayered constructions in the form of bottles, tanks, large hollow articles, rigid food containers, and toys, for example.
The thermoplastic polymeric mixture of the present application may be formed into compositions that contain other compounds which are customary in polymer compositions. These compounds can include flame retardants, colorants, antioxidants, antiozonates, light stabilizers, fillers, foaming agents, and the like. The level of the other compounds may be from 0 to 99 weight parts based on 100 weight parts of the total weight of the thermoplastic polymeric mixture, depending on the desired end use application. If other ingredients are used, they may be mixed into the composition in the reactive melt blend, or they may be added post-reaction in a compounding step. Compounding ingredients into polymer formulations is well-known to those skilled in the art. Melt mixing equipment such as extruders, two roll mills, Banbury mixers, and the like, may be used in the compounding step.
A third aspect of the present application relates to a method of forming a thermoplastic graft copolymer. This method includes:
with a branched chain thermoplastic polymer of formula II:
where
The grafting reaction of the thermoplastic polymers of formula (I) and the thermoplastic polymers of formula (II) may be conducted in a molten state inside an extruder, such as for example a single extruder or a twin-screw extruder. Such process is often referred to as reactive extrusion or melt blending.
The thermoplastic graft copolymer of the present application may be formed via reactive extrusion. Any reactive extrusion process known in the art and literature may be used to perform the reaction. Suitable processes include melt blending in a single screw extruder, a twin screw extruder, on a two roll mill, a screw feeding injection molding machine, or in an internal mixture such as a Banbury mixer. In one embodiment of the present application, an extruder is used to melt blend the ingredients to form the thermoplastic graft copolymer.
A screw extruder is a machine in which material, usually some form of plastic, is forced under pressure to flow through a contoured orifice in order to shape the material. Screw extruders are generally composed of a housing, which is usually a cylindrical barrel section, surrounding a central motor-driven screw. At a first end of the barrel is a feed housing containing a feed opening through which new material, usually plastic particles, is introduced into the barrel. The screw contains raised portions called flights having a larger radial diameter than the screw's central shaft and which are usually wrapped in a helical manner about the central shaft. The material is then conveyed by these screw flights toward the second end of the barrel through a melting zone, where the material is heated under carefully controlled conditions to melt the material and allow for the reaction of the polymers. The reacted polymer then passes through a melt-conveying zone, also called a pumping zone. The melted polymer is finally pressed through a shaped opening or die to form the extrudate.
Besides conveying material toward the die for extrusion, the screw is depended upon to perform mixing of the feed material. Very generally, mixing can be defined as a process to reduce the non-uniformity of a composition. The basic mechanism involved is to induce physical motion in the ingredients. The two types of mixing that are important in screw extruder operation are distribution and dispersion. Distributive mixing is used for the purpose of increasing the randomness of the spatial distribution of the particles without reducing the size of these particles. Dispersive mixing refers to processes that reduce the size of cohesive particles as well as randomizing their positions. In dispersive mixing, solid components, such as agglomerates, or high viscosity droplets are exposed to sufficiently high stresses to cause them to exceed their yield stress, and they are thus broken down into smaller particles. The size and shape of the agglomerates and the nature of the bonds holding the agglomerate together will determine the amount of stress required to break up the agglomerates. The applied stress can either be shear stress or elongational stress and generally, elongational stress is more efficient in achieving dispersion than is shear stress. An example of dispersive mixing is the manufacture of a color concentrate where the breakdown of pigment agglomerates below a certain critical size is crucial. An example of distributive mixing is the manufacture of miscible polymer blends, where the viscosities of the components are reasonably close together. Thus, in dispersive mixing, there will always be distributive mixing, but distributive mixing will not always produce dispersive mixing.
In screw extruders, significant mixing occurs only after the polymers have melted. Thus, the mixing zone is thought of as extending from the start of the melting zone to the end of the extrusion die. In molten polymers, the stress is determined by the product of the polymer melt viscosity and rate of deformation.
The use of single and twin screw extruders for reactive extrusion is commonly known in the art. Further disclosure of screw extruders which may be used for reactive extrusion is found in U.S. Pat. No. 8,101,108 to Otoshi; U.S. Pat. No. 7,960,473 to Kobayashi et al.; U.S. Pat. No. 6,074,084 to Kolossow; U.S. Pat. No. 5,932,159 to Rauwendaal; and U.S. Patent Application No. US20180163901 to Gopalan et al, which are hereby incorporated by reference in their entirety.
Screw feeding injection molding is a process which comprises melting a material, such as a plastic, primarily by shear heat that is dynamically generated by rotation of an extrusion screw. Screw feeding injection molding is commonly known in the art and is disclosed in U.S. Pat. No. 5,002,717 to Taniguchi; U.S. Pat. No. 2,734,226 to Willert; U.S. Pat. No. 6,676,864 to Hawley; and U.S. Pat. No. 9,931,773 to Fitzpatrick, which are hereby incorporated by reference in their entirety.
Banbury mixers consist of a kneading chamber having a closed structure, which can produce a large shear force created by a pair of rotors that are reversed in this state. Banbury mixers have been known and used extensively in the rubber industry for many years for masticating raw or uncured rubber or preparing curable rubber compositions. The general construction is described, for example, in U.S. Pat. No. 1,881,994 to Banbury, which is hereby incorporated by reference in its entirety, and improved versions of this machine have been in use for many years and are well understood by those in the rubber industry without further description. Detailed descriptions of modern Banbury machines and their use can be found in U.S. Pat. No. 3,294,720 to Beber et al.; U.S. Pat. No. 8,586,651 to Wang et al., U.S. Pat. No. 9,365,497 to Watanabe et al.; and U.S. Pat. No. 3,897,070 to Anderson et al., which are hereby incorporated by reference in their entirety.
The thermoplastic polymer of formula (I) a can be fed to the extruder in pellet form, as is commercially available. The thermoplastic polymer of formula (II) can be fed in liquid or solid form (granulates or flakes) to the extruder. Alternatively, the thermoplastic polymer of formula (II) can be coated onto the thermoplastic polymer of formula (I) before being fed into the mixer of the extruder. The thermoplastic polymer of formula (II) may be dissolved in a solvent, such as sub-epoxidized soybean oil, soybean oil, epoxidized soybean oil, methyl soyate, epoxidized methyl soyate, epoxidized soyate benzyl soyate, isoamyl soyate, vegetable oils, fatty acid methyl esters, epoxidized fatty acid methyl esters, citrate esters, other plasticizers, and mixtures thereof. The thermoplastic polymer of formula (II) in the solvent may be in a concentration ranging from 1 wt % to 99 wt %. The mixing temperature of the melt in the extruder will be a temperature sufficient to melt the polymers such that they can be processed through an extruder. The exact temperature used will depend on the melt processing temperature of the highest melting point polymers used in the blend. Melt processing temperatures may range from 100° C. to 300° C., for example from 100° C., 110° C., 120° C., 130° C., 140° C., 150° C., 160° C., 170° C., 180° C., 190° C., 200° C., 210° C., 220° C., 230° C., 240° C., 250° C., 260° C., 270° C., 280° C., or 290° C., to 110° C., 120° C., 130° C., 140° C., 150° C., 160° C., 170° C., 180° C., 190° C., 200° C., 210° C., 220° C., 230° C., 240° C., 250° C., 260° C., 270° C., 280° C., 290° C., or 300° C., as can be well understood by those skilled in the art of polymer blending. The ingredients are in the extruder for a period of time sufficient to allow for the formation of the engineering thermoplastic. This can range in time from 1 s to 600 s. For example, the time may range from about 1 s, 10 s, 50 s, 100 s, 200 s, 300 s, 400 s, or 500 s up to about 10 s, 50 s, 100 s, 200 s, 300 s, 400 s, 500 s, or 600 s. The weight percent ratio of the thermoplastic polymers of formula (I) and the thermoplastic polymers of formula (II) may range from 1 wt % to 99 wt %. For example, the weight percent ratio of the thermoplastic polymers of formula (I) and the thermoplastic polymers of formula (II) may range from about 1 wt %, 10 wt %, 20 wt %, 30 wt %, 40 wt %, 50 wt %, 60 wt %, 70 wt %, 80 wt %, or 90 wt % up to about 10 wt %, 20 wt %, 30 wt %, 40 wt %, 50 wt %, 60 wt %, 70 wt %, 80 wt %, 90 wt %, or 99 wt %.
After exiting the extruder, the polymer can be pelletized and stored as is typical. Furthermore, the polymer would not always need to be pelletized, but rather could be extruded directly from the reaction extruder through a die into a final product profile.
The reactive extrusion technique has been used for decades as a tool to produce polymer blends and other hybrids. The process is generally viewed as efficient and effective means to bring together otherwise thermodynamically incompatible materials. High temperatures and strong shear forces drive chemical reactions over the short residence times involved to produce hybrid polymers the serve as compatibilizers to stabilize the mixture. For example, Moad provided an extensive review of methodologies employed to form polyolefin hybrids, often through free radical mediated chemistry (Moad, G. “The Synthesis of Polyolefin Graft Copolymers by Reactive Extrusion,” Prog. Polym. Sci. 24:81-142(1999), which is hereby incorporated by reference in its entirety). Polyesters are also well-suited to this processing strategy, where additives like maleic anhydride are often used to form chemical bridges with other materials like starches (Carlson, et al., Maleation of Polylactide (PLA) by Reactive Extrusion”, J. Appl. Polym. Sci. 72(4):477-485 (1999), which is hereby incorporated by reference in its entirety).
Thermoplastic poly((meth)acrylated epoxidized triacyl glycerides) (PAETAG) are branched chain polymers with (meth)acrylate primary chains and AETAG-derived pendant groups. Since AETAGs have a distribution in the number of (meth)acrylate functionalities, multiply (meth)acrylated instances can be present both as branch points and sources of residual vinyl functionality in the PAETAG. Moreover, PAETAGs contain ester, oxirane and alcohol moieties throughout the macromolecule. This diversity of chemical groups presents an unusually broad variety of mechanisms through which compatibilizing graft copolymers can be formed in a reactive extrusion process. For example, poly(acrylated epoxidized high oleic soybean oil) (PAEHOSO) can dynamically form ester bonds with polyesters or polyamides through the ring opening esterification of an oxirane group with a free acid or amine. Through these covalent bonds, PAEHOSO-polyester graft copolymers could be produced to promote thermodynamically stable blends of the constituent components. A potentially complicating issue is the thermal stability of the PAETAG. PAETAG is unusual as a thermoplastic polymer since its monomer is multiply functional, which necessarily implies a tendency to form thermosets, i.e. infinite polymer networks. Thermoplastic PAETAG is formed when the formation of this network is suppressed through processes like controlled radical polymerization. However, the application of heat to concentrated PAETAG generates further thermally generated free radicals that quickly cure the polymer to transform it to a thermoset. Surprisingly, when melt processed with other polymers like polylactide, macrogelation does not occur and the resultant polymer blends remain thermoplastic and melt processable.
Currently, acrylated epoxidized vegetable oils have shown promise as potentially low Tg thermoset plasticizers (Mauck et al., Macromolecules 49:1605-1615 (2016), which is hereby incorporated by reference in its entirety). These vegetable oils contain many reactive chemical moieties such as epoxy, acrylic, and alcohol functionality that can be reacted in an extruder barrel with various other polyesters; however, as stated previously, plasticizers can significantly alter the Tg of PLA. Therefore, the polymerization of the vegetable oils discussed in the present application is an ideal way to preserve the PLA glass transition temperature. With the innate ability for the acrylic functionality to undergo polymerization, acrylated vegetable oils can undergo polymerization via reversible addition fragmentation chain transfer to generate high molecular weight homopolymers, copolymers, and block copolymers which can be used to synthesize a biobased thermoplastic elastomer. A series of poly acrylated epoxidized high oleic soybean oil polymers (PAHOESO) at varying molecular weights, polymer architectures and compositions were synthesized. This strategy is an effective way to toughen PLA and stabilize the interface between the PLA and oil domains at a low cost bioderived alternative to petroleum based engineering thermoplastics and petroleum based impact modifiers.
Preferences and options for a given aspect, feature, embodiment, or parameter of the technology described herein should, unless the context indicates otherwise, be regarded as having been disclosed in combination with any and all preferences and options for all other aspects, features, embodiments, and parameters of the technology.
The present technology may be further illustrated by reference to the following Examples which are presented to illustrate various aspects of the present application, but are not intended to limit the scope of the claims.
Epoxidized High Oleic Soybean Oil (EHOSO) was supplied by CHS, triethylamine, hydroquinone, and acrylic acid were all purchased from Sigma Aldrich with purity of 99% or higher. Carbon Disulfide, ethane thiol, p-tosyl chloride and azobisisobutyronitrile were purchased from Sigma Aldrich. Glycidyl methacrylate, 2,2-azobis 2-methylpropionitrile, and dioxane were purchased from Sigma Aldrich with purities of 98% or higher. Methanol was purchased from Fischer scientific with a purity of 99.8%. The asphalt binder with a PG grade of 64-22 was obtained from a Jebro asphalt terminal in Sioux City, Iowa. A linear SBS polymer was used as received along with elemental sulfur and poly-phosphoric acid (PPA).
100 g of EHOSO (0.103 mol), 27.5 g of acrylic acid (0.319 mol), 0.893 g triethylamine (0.7% w/w of EHOSO), and 1.6 g hydroquinone (1.25% w/w of EHOSO) were added in a round bottom flask agitated with magnetic stirring. The flask was flushed with Argon and was allowed to react 4 hours at 110° C. with septa to achieve an acrylic functionality of 2.15. After the reaction was completed, distillation was performed at 100° C. under vacuum to remove the excess acrylic acid. 1H-NMR (Bruker, AVII, 600 MHZ) in CDCl3 was used to confirm structure and purity: δ 0.8-1.1 ppm (t, 9H, CH3CH2), δ 2.2-2.4 ppm (m, 6H, COCH2CH2), δ 4.2-4.4 ppm (m, 4H, 2xCH2), δ 5.70-6.5 ppm (m, 3H, CH2CH2) as shown in
50 g of Acrylated Epoxidized High Oleic Soybean Oil (0.0454 mols), 0.1894 g of 2,2-azobis(2-methylpropionitrile) (0.00115 mols), 0.0157 g (0.000077 mols) of 2-ethyl(3-oxobutan-2-yl) carbonotrithioate (OxCART), and 51.5 g (0.0568 mols) of sub-epoxidized soybean oil (SESO) were added to a round bottom flask equipped with a stir-bar. The reaction vessel was purged for 30 minutes with argon and the reaction proceeded at 100° C. for 2 hours. The reaction was quenched with the addition of hydroquinone at 0.1% by wt of the reaction contents. The reaction scheme can be seen in
30 g of glycidyl methacryalate (0.2113 mols), 0.1153 g of 2,2-azobis(2-methylpropionitrile) (0.0006 mols), 0.615 g (0.0030 mols) of 2-cyanopropan-2-yl methyl carbonotrithioate (CYCART), and 31 g (0.3517 mols) of dioxane were added to a round bottom flask equipped with a stir-bar. The reaction vessel was purged for 30 minutes with argon and the reaction proceeded at 80° C. for 4 hours. The reaction was precipitated in methanol and dried at 50° C. overnight. A small sample was then taken to perform gel permeation chromatography (GPC) to determine molecular weight.
12 g (0.0100 mols) of acrylated epoxidized high oleic soybean oil (AHOESO), 3 g (0.062236 mols) of PGMA-RAFT CTA from Example 3, 0.05768 g (0.00119 mols) of AMBN (2,2′-azodi(2-methylbutyronitrile)), and 33.14 g (0.376 mols) of dioxane were added to a round bottom flask equipped with astir-bar. The reaction vessel was purged for 30 minutes and then the reaction proceeded at 80° C. for 2.5 hours. The reaction was then precipitated in methanol and dried. A small sample was taken for NMR to determine the composition. 1H-NMR (Bruker, AVII, 600 MHz) in CDCl3 was used to confirm the structure and composition.
The fabrication of the A+B or A+B+AB polymer blends was performed by extruding a calculated amount of polymermodifier with various amounts of PLA depending on the composition. The polymer was then melt blended using a Haake miniLab twin screw extruder. The extrudate was cooled and prepared for injection molding. The blends were synthesized at 220° C. with a 10-minute residence time.
The BABS-A blend consists of poly acrylated epoxidized high oleic soybean oil (PAEHOSO) polymerized in its sub epoxidized soybean oil (SESO) solvent at a 1:1 mass ratio with a target molecular weight of 500 kDa. The PAEHOSO and SESO reactor product is then physically mixed together at a loading of 10wt % with PLA at room temperature. The physically mixed product is then put into the Haake compounder at 5 g per cycle at 220° C. After 10 minutes, the extrudate was extruded from the compounder to yield the BABS-A blended product.
The BABS series was thought to be a possible impact modifier for PLA as the polymer mixture contains a Tg of −40° C. and has epoxide functionality that can chain extend with the carboxylic acid end groups of PLA to stabilize the interface between the soybean elastomer and PLA. The results showed an increase in elongation at break; however, switching to a methacrylic backbone was thought to increase the mechanical performance since polymethyl methacrylate (PMMA) is known to be miscible with PLA. An increase in the interfacial adhesion using a methacrylic backbone would yield smaller micelles increasing mechanical performance.
The BABSMA-A blend consists of poly methacrylated epoxidized high oleic soybean oil (PMAEHOSO) polymerized in its sub epoxidized soybean oil solvent at a 1:1 mass ratio with a target molecular weight of 500 kda. The PMAEHOSO and SESO reactor product is then physically mixed together at a loading of 10wt % with PLA at room temperature. The physically mixed product was then put into the Haake compounder at 5 g per cycle at 220° C. After 10 minutes, the extrudate was extruded from the compounder to yield the BABSMA-A blended product.
The BABSMA series was thought to be a possible impact modifier for PLA as the polymer mixture contains a Tg of −46° C. and has epoxide functionality that can chain extend with the carboxylic acid end groups of PLA to stabilize the interface between the soybean elastomer and PLA. A further increase in the elongation was seen by switching to a methacrylic backbone; however, it was decided that synthesizing statistical copolymers of PMMA with PAHOESO would increase the interfacial adhesion between the dispersed phase and the PLA matrix.
The BABSCO-B blend consists of PMMA copolymerized with PAEHOSO with a target MW of 500 kDa. 50 g (0.0418 moles) of AEHOSO, 22 g of MMA (0.2195 moles), 0.0138 g of AMBN (7.2E−5 moles), 0.02951 g of CyCART (1.44E−4 moles), and finally 70 g of SESO were added to a 3-neck round bottom flask equipped with a mechanical agitator. The reactor flask was then purged with argon for 30 minutes before being reacted at 100° C. The reaction then proceeded for 1.5 hours before the reaction was quenched with inhibitor. H-NMR (Bruker, AVII, 600 MHz) in CDCl3 was used to confirm the structure and composition of ˜30 wt % PMMA. The reactor product was then physically mixed together at a loading of 20 wt % with PLA at room temperature. The physically mixed product was then put into the Haake compounder at 5 g per cycle at 220° C. After 10 minutes, the extrudate was extruded from the compounder to yield the BABSCO-B blended product.
The elongation showed an increase by 2 orders of magnitude; however, the impact strength was still found to not increase. In order to increase the impact strength, it was thought that a highly entangled rubber would be required. Ethylene-co-methyl acrylate-co-glycidyl methacrylate (EMA-GMA) was selected as a potential candidate to increase the impact strength
BABSELVA is a ternary blend of 10 wt % PAEHOSO with SESO and 10 wt % EMA-GMA. The materials were physically mixed together prior to extruding in the Haake extruder. The physically mixed product was then put into the Haake compounder at 5 g per cycle at 220° C. After 10 minutes, the extrudate was extruded from the compounder to yield the BABSELVA-F blended product.
The impact strength was shown to increase by an order of magnitude confirming that an entangled rubber would be necessary to receive increases in impact strength. While the impact strength increased, the compostability aspect of the blend was removed. In order to combat this pure polymer was synthesized with the thought that removal of the plasticizer would help combat the decrease in impact strength observed.
PAHMA-A was synthesized with a target MW of 500 kDa. 50 g of Methacrylated Epoxidized High Oleic Soybean Oil (0.0454 mols), 0.1894 g of 2,2-azobis(2-methylpropionitrile) (0.00115 mols), 0.0157 g (0.000077 mols) of 2-cyanopropan-2-yl methyl carbonotrithioate (CyCART), and 51.5 g of dioxane were added to a round bottom flask equipped with a stir-bar. The reaction vessel was purged for 30 minutes with argon, and the reaction proceeded at 80° C. for 2 hours. The reaction was quenched with the addition of hydroquinone at 0.1% by wt of the reaction contents. The reaction contents were precipitated in methanol and then dried in the vacuum ovens for 4 hours. This product is referred to as PMAEHOSO in
The material properties showed the removal of SESO had a large effect on the tensile toughness attributing to a 2 orders of magnitude increase from the BABSMA-A blend; however, the impact strength was relatively unaffected.
The PAHCO-A blend consists of PMMA copolymerized with PAEHOSO with a target MW of 500 kDa. 50 g (0.0418 moles) of AEHOSO, 22 g of MMA (0.2195 moles), 0.0138 g of AMBN (7.2E−5 moles), 0.02951 g of CyCART (1.44E−4 moles), and finally 70 g of dioxane. This polymer is referred to as PMMA-stat-PAEHOSO in
30 g of glycidyl methacryalate (0.2113 mols), 0.1153 g of 2,2-azobis(2-methylpropionitrile) (0.0006 mols), 0.615 g (0.0030 mols) of 2-cyanopropan-2-yl methyl carbonotrithioate (CYCART), and 31 g (0.3517 mols) of dioxane were added to a round bottom flask equipped with a stir-bar. The reaction vessel was purged for 30 minutes with argon and the reaction proceeded at 80° C. for 4 hours. The reaction was precipitated in methanol and dried at 50° C. overnight yielding PGMA-RAFT-CTA. A small sample was then taken to perform gel permeation chromatography (GPC) to determine molecular weight. The molecular weight was determined to be ˜8 kDa using PMMA standards. 12 g (0.0100 mols) of acrylated epoxidized high oleic soybean oil (AEHOSO), 3 g (0.062236 mols) of PGMA-RAFT CTA from Example 3, 0.05768 g (0.00119 mols) of AMBN (2,2′-azodi(2-methylbutyronitrile)), and 33.14 g (0.376 mols) of dioxane were added to a round bottom flask equipped with a stir-bar. The reaction vessel was purged for 30 minutes and then the reaction proceeded at 80° C. for 2.5 hours. The reaction was then precipitated in methanol and dried. A small sample was taken for NMR to determine the composition. 1H-NMR (Bruker, AVII, 600 MHz) in CDCl3 was used to confirm the structure and composition. The product yielded a block copolymer with an Mn of ˜20 kDa with a block composition of ˜10 wt % PGMA. This product is referred to as PGMA-block-PAEHOSO in
The polymer blend yielded excellent mechanical properties showing both an order of magnitude increase in tensile toughness and impact strength. This is likely due to the ability of the PGMA block to form a corona around the PAEHOSO core allowing for the synthesis of a core-shell micelle.
PAHTERN is a ternary blend using PGMA-block-PAEHOSO at 10 wt %, polybutylene succinate (PBS) at 20 wt %, and PLA at 70 wt %. The mixture was extruded using the Hakke extruder with a cycle time of 10 minutes at 190° C. The polymer blend yielded a blend that showed an order of magnitude increase in impact strength showing that PGMA-block-PAEHOSO could be used to compatibilize PBS with PLA. PBS is known to be readily compostable while PLA is industrially compostable with the goal that a small amount of PBS chain extended with PLA would yield an engineering thermoplastic that is durable and readily compostable.
Formulations of the different polymer blends are shown in Table 1. The GPC of exemplary polymer PAHBLO-A is shown in
Sample code and biopolymers: The biopolymer for BABS and BABSELVA samples is 500 kDa PAEHOSO; the biopolymer for BABSMA and PAHMA is 500 kDa PMAEHOSO; the biopolymer for BABSCO and PAHCO biopolymer is 500 kDa PMMA/PAEHOSO; the biopolymer for PAHBLO and PAHTERN is PGMA-PAEHOSO.
The extrudate was used to make ASTM D256 IZOD bars and ASTM D638 Type 5 dogbones. A Haake MiniJet injection molder was used with the barrel temperature set to 240° C. and a mold temperature of 40° C. The Ram pressure was set to 700 bar. Notches were then created under the ASTM D256 Specifications. ASTM D256 specifications can be described as having dimensions of 63.5×12.5×3.2. The dimensions are all in millimeters where the length, width, and thickness of the IZOD bar correspond to the values above.
Uniaxial tensile tests were performed with an Instron 3367 tensile testing machine using a cross-head moving rate of 5 mm/min. Images of the samples after tensile tests are shown in
Analysis of polymers microstructure was performed on a 200 kV JEOL 2100 Scanning/Transmission Electron Microscope. Each TEM specimen was ultra-microtomed at −70° C. in the whitened gauge region of the tensile bar, shown in
The PLA blends were all prepared via reactive extrusion. The reactive extrusion process between PLA, the various PAHOESO polymer architectures, and SESO utilizes the epoxy rings and the carboxylic acid chemical moieties. The resultant blends would then branch and form graft copolymers inducing compatibility between the PLA phase and the oil phases. TEMs showing a compatibilized blend can be seen in
A series of reactive PAHOESO polymer architectures were uniformly dispersed as differing morphology micelles resulting in compatibilized A+B+AB polymer blends. The mechanical properties showed an order of magnitude increase in tensile toughness and notched izod impact strength over neat PLA. The micelles toughen the PLA matrix by inducing cavitation, crazing, and shear yielding throughout the thermoplastic matrix while undergoing deformation depending on the polymer architecture. These results show that a biobased polyester can be toughened with a biobased polymer at low loadings while maintaining the thermal and mechanical properties of the original matrix.
The A+B+AB polymer blends can be formed inside the extruder barrel. These AB-type polymers could be used as a dispersed phase to chain extend with the matrix yielding graft copolymers in the extruder barrel. Originally, the BABS series blends were thought to be able to be used as a high-performance impact modifier; however, only the elongations of the polymer blends could be improved. Since it is well known that PMMA is miscible with PLA, exchanging out the acrylic AEHOSO backbone (BABS) with a methacrylic backbone (BABSMA) was thought to provide an increase in the interfacial adhesion between the soybean rubber phase and the PLA rigid phase. While improvements in the tensile properties can be seen, the impact strength was once again a concern. Copolymers of the BABSCO blends display the addition of ˜30 wt % PMMA statistically polymerized into the AEHOSO backbone can increase the elongation at break of 2 orders of magnitude higher than the BABSMA series. This is because PMMA is miscible with PLA, enhancing the adhesion between the soybean copolymer rubber and the PLA matrix. The impact strength was still unaffected, likely due to the lack of the rubber containing entanglements that provide elasticity. With this concept in mind, BABSELVA blends were synthesized. EMA-GMA is an ethylene-based highly entangled rubber that when extruded with PLA can enhance the impact strength. This blend showed an order of magnitude increase in impact strength; however, the compostability aspect of the blend was effectively eliminated. Since the compostability aspect of the blend was the ultimate goal, the removal of SESO from the soybean-based polymer was thought to help increase the impact strength since plasticizers cannot undergo common deformation mechanisms. PAHCO and PAHMA blends, which contain no SESO, showed similar results to BABSCO blends where large increases in tensile properties were observed without increases in impact strength. Ultimately, a block copolymer was formulated with the thought that a reactive amphiphilic block copolymer would allow for the synthesis of a core-shell micelle with a PGMA corona and a PAEHOSO core. PAHBLO-L showed both an order of magnitude increase in tensile toughness and impact strength. Finally, PAHTERN was synthesized with the goal of a durable thermoplastic blend that was also readily compostable. PLA is known to be industrially compostable while PBS is “backyard” compostable. A blend with a small percentage of PBS with PGMA-block-PAEHOSO as the compatiblizer could be used to give a blend that is both extremely durable and readily compostable.
Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the claims which follow.
This application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 63/170,178, filed Apr. 2, 2021, which is hereby incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/023113 | 4/1/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63170178 | Apr 2021 | US |
