WO2025163492A1 - Foamed material, method for the manufacture thereof, and articles comprising the foamed material - Google Patents

Abstract

A foamed material includes particular amounts of a poly(phenylene ether), a polystyrene, a nucleating agent, and optionally a flame retardant. The foamed material has 20 to 100 kilograms per cubic meter, measured at 23 °C and a closed cell content of greater than 90%. Methods of making the foamed material and articles including the foamed material are also described.

Description

23SHPP0032-WO-PCT (SS220061PCT) FOAMED MATERIAL, METHOD FOR THE MANUFACTURE THEREOF, AND ARTICLES COMPRISING THE FOAMED MATERIAL CROSS-REFERENCE TO RELATED APPLICATION This application is based on and claims the benefit of European Patent Application No. 24154354.5, filed January 29, 2024, the contents of which are incorporated by reference herein in their entirety. BACKGROUND [0001] Disclosed herein are extruded polystyrene foamed materials. Methods for the manufacture of the extruded polystyrene foamed materials and articles including the extruded polystyrene foamed materials are also disclosed. [0002] Foamed polymer materials such as extruded foam board are widely used in building and insulation applications. Requirements for these applications include excellent thermal insulation properties, good compression strength, and excellent flame retardant properties. The majority of the commercial flame retardant foams in building applications include halogenated flame retardants. Two examples of commercial flame retardant foamed materials used in building applications are flame retardant extruded polystyrene (XPS) and flame retardant expandable polystyrene (EPS), both of which contain brominated flame retardants. For example, hexabromocyclododecane (HBCD) is the most commonly used halogenated flame retardant (FR) agent used in polystyrene foamed materials. Increasingly, regulatory authorities are demanding that insulating foams exclude halogenated flame retardants. [0003] There is therefore a needed for insulating foam compositions that exhibit excellent flame retardancy without incorporating halogenated flame retardants. It would be particularly advantageous to provide a foamed material that exhibits a desirable combination of compression strength and tensile properties. It would be further advantageous if such a foam board could pass the flammability testing according to the test method Federal Motor Vehicle Safety Standards (FMVSS) and ISO9772. SUMMARY [0004] An extruded foamed material comprising: 50 to 94.9 weight percent of polystyrene; 5 to 49.9 weight percent of a poly(phenylene ether); 0.1 to 5 weight percent of a nucleating agent; and optionally, 0.5 to 20 weight percent of an organophosphate ester flame retardant; wherein weight percent is based on the total weight of the foamed material; wherein 23SHPP0032-WO-PCT (SS220061PCT) the foamed material has a density of 20 to 100 kilograms per cubic meter, measured at 23 °C; a closed cell content of greater than 90%; and wherein a block copolymer of an alkenyl aromatic and a conjugated diene is excluded from the composition. [0005] Another aspect is a method of making the above-described foamed material, the method including: melt blending a first portion of polystyrene, the poly(phenylene ether),; and optionally, the organophosphate ester flame retardant to provide a masterbatch; melt blending in an extruder the masterbatch, a second portion of polystyrene, and the nucleating agent to form a molten thermoplastic composition; adding a blowing agent to the extruder to form a pre-foamed molten thermoplastic composition; and extruding the pre-foamed molten thermoplastic composition from the extruder to form the foamed material or board. [0006] Another aspect is an article comprising the foamed material. [0007] The above described and other features are exemplified by the following detailed description and claims. DETAILED DESCRIPTION [0008] The present inventors have discovered an extruded foamed material that can overcome one or more of the above-described technical limitations of existing foamed materials. The foamed material includes particular amounts of polystyrene, poly(phenylene ether), a nucleating agent, and, optionally, a flame retardant. Advantageously, the extruded foamed material according to the present disclosure has a density of 20 to 100 kilograms per cubic meter (kg/m³), measured at 23°C and a closed cell content of greater than 90%. Further, the extruded foamed materials can exhibit a desirable combination of one or more properties including improved compression strength, thermal conductivity, tensile strength, bending stiffness, and thermal and dielectric stability. In an aspect, the extruded foamed materials can also achieve pass ratings in flammability testing according to at least one of FMVSS or ISO9772 test standards in the absence of a halogenated flame retardant additive. A significant improvement can therefore be provided by the present disclosure. [0009] In an aspect, an extruded foamed material comprises polystyrene. As used herein, the term polystyrene refers to a homopolymer of styrene. Thus, the residue of any monomer other than styrene is excluded from the polystyrene. The polystyrene can be atactic, syndiotactic, or isotactic. In some aspects, the polystyrene comprises an atactic polystyrene having a melt flow index of 1.5 to 15 grams per 10 minutes (g/10 min), measured at 200°C and 5 kilogram (kg) load according to ASTM D1238-13. Within this range, the melt flow index can be 3 to 14 grams per 10 minutes, specifically 5 to 13 grams per 10 minutes. In an aspect, the 23SHPP0032-WO-PCT (SS220061PCT) polystyrene can comprise an atactic homopolystyrene having a melt flow index of 1.5 to 15 grams per 10 minutes, measured at 200 °C and 5 kilogram load according to ASTM D1238-13. [0010] The foamed material comprises the polystyrene in an amount of 50 to 94.9 weight percent, based on the total weight of the foamed material. Within this range, the polystyrene can be present in an amount of at least 50 weight percent, or at least 55 weight percent, or at least 60 weight percent, or at least 65 weight percent. Also within this range, the polystyrene can be present in an amount of at most 93.9 weight percent, or 90 weight percent, or 85 weight percent, or 80 weight percent, or 75 weight percent, or 74.9 weight percent. For example, in an aspect, the polystyrene can be present in an amount of 65 to 74.9 weight percent, based on the total weight of the foamed material. In an aspect, the polystyrene can be present in an amount of 50 to 93.9 weight percent, based on the total weight of the foamed material. [0011] In addition to the polystyrene, the foamed material comprises a poly(phenylene ether). Poly(phenylene ether)s as used herein includes those comprising repeating structural units having the formula wherein each occurrence of Z¹ is independently C1-12 hydrocarbylthio, C1-12 hydrocarbyloxy, C2- 12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms, or unsubstituted or substituted C1-12 hydrocarbyl provided that the hydrocarbyl group is not tertiary hydrocarbyl; and each occurrence of Z² is independently hydrogen, C1-12 hydrocarbylthio, C1-12 hydrocarbyloxy, C2-12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms, or unsubstituted or substituted C1-12 hydrocarbyl provided that the hydrocarbyl group is not tertiary hydrocarbyl. As used herein, the term “hydrocarbyl”, whether used by itself, or as a prefix, suffix, or fragment of another term, refers to a residue that contains only carbon and hydrogen. The residue can be aliphatic or aromatic, straight-chain, cyclic, bicyclic, branched, saturated, or unsaturated. It can also contain combinations of aliphatic, aromatic, straight chain, cyclic, bicyclic, branched, saturated, and unsaturated hydrocarbon moieties. However, when the hydrocarbyl residue is described as substituted, it can, optionally, contain heteroatoms (other than halogens) over and above the 23SHPP0032-WO-PCT (SS220061PCT) carbon and hydrogen members of the substituent residue. Thus, when specifically described as substituted, the hydrocarbyl residue can also contain one or more carbonyl groups, amino groups, hydroxyl groups, or the like, or it can contain heteroatoms within the backbone of the hydrocarbyl residue. As one example, Z¹ can be a di-n-butylaminomethyl group formed by reaction of a terminal 3,5-dimethyl-1,4-phenyl group with the di-n-butylamine component of an oxidative polymerization catalyst. [0012] The poly(phenylene ether) can comprise compounds having aminoalkyl-containing end group(s), typically located in a position ortho to the hydroxyl group. Also frequently present are tetramethyldiphenoquinone (TMDQ) end groups, typically obtained from 2,6-dimethylphenol-containing reaction mixtures in which tetramethyldiphenoquinone by-product is present. The poly(phenylene ether) can be in the form of a homopolymer, a copolymer, a graft copolymer, an ionomer, or a block copolymer, as well as combinations thereof. Preferably, the poly(phenylene ether) is in the form of a homopolymer. [0013] In an aspect, the poly(phenylene ether) can have an intrinsic viscosity of 0.2 to 1 deciliter per gram (dl/g) measured by Ubbelohde viscometer at 25°C in chloroform. Within this range, the poly(phenylene ether) intrinsic viscosity can be 0.3 to 0.65 deciliter per gram, more specifically 0.25 to 0.5 deciliter per gram, even more specifically 0.29 to 0.45 deciliter per gram. In an aspect, the poly(phenylene ether) can have an intrinsic viscosity of 0.2 to 1 deciliter per gram, preferably 0.4 to 0.6 deciliters per gram. [0014] In an aspect, the poly(phenylene ether) is a homopolymer. For example, the poly(phenylene ether) can be a homopolymer consisting of repeating units derived from of 2,6- dimethylphenol. In an aspect, a poly(phenylene ether) other than a homopolymer of phenylene ether can be excluded from the foamed material. [0015] The poly(phenylene ether) can optionally be in the form of a copolymer of two or more monomers, for example a terpolymer, and the raw materials used to produce the poly(phenylene ether) can be, or can be formed from, renewable, sustainable, bio-circular, circular, lower carbon footprint feedstocks, upcycled, and/or post-consumer/ post-industrial recycled materials, including pyrolysis oil (“py-oil”) . [0016] Poly(phenylene ethers) made from renewable sources can include, for example, a bio-content or PCR content of up to about 99.9%, about 1 to 99%, 5 to 95%, 55 to 99%, or 80-to 99%, 1 to 50%, 1 to 25%, 1 to 15%, 1 to 10%, or 1 to 5%, based, e.g., on the monomer source. The poly(phenylene ether) can be, e.g., an oligomer with as few as two repeating units to ultra- high molecular weight poly(phenylene ethers). The weight average molecular weight of the poly(phenylene ether) in a non-limiting embodiment can be 600 to 200,000 grams per mole, as 23SHPP0032-WO-PCT (SS220061PCT) determined by gel permeation chromatography. In another non-limiting embodiment, the poly(phenylene ether) can have an intrinsic viscosity of up to 1.5 deciliters per gram (dl/g) as measured at 25°C in chloroform. Poly(phenylene ether) made from renewable sources can include material made by a mass balance approach and certified by regulatory bodies such as, for example, the ISCC Plus. [0017] Poly(phenylene ether) in an embodiment can be prepared by oxidative polymerization of monomers in the presence of a polymerization catalyst in the presence of oxygen. Any of the components used in the polymerization reaction or their synthetic precursors, or the solvents used in the process, can be bio-sourced, bio-circular, or renewable raw materials. Such components and precursors include monomers (e.g., monohydric phenol, dihydric phenol and other comonomers), reagents, solvents, catalysts (e.g., a metal source, a secondary alkylene diamine ligand, a tertiary monoamine, and optionally a secondary monoamine or alternatively enzyme catalysts), gases (e.g., oxygen gas), or any combinations thereof. In some aspects, reaction components used in the polymerization of poly(phenylene ethers) can be from sources as listed in the EU Renewable Energy Directive Annex IX. [0018] Poly(phenylene ether) can be further processed, such as by redistribution, or any chemical derivatization, such as post-polymerization end-group capping or coupling, to make other materials that can transfer the sustainability characteristic to the new material. Such reagents and/or their synthetic precursors can be sustainable, bio-sourced, bio-circular, or renewable raw materials, upcycled, and/or post-consumer/ post-industrial recycled materials, including pyrolysis oil (“py-oil”), to produce a poly(phenylene ether). [0019] Biosourced and sustainable materials can be derived from biomass sources or industrial sources such as waste (e.g., municipal waste). Biomass is a renewable organic material that comes from organic matter. Lignocellulosic biomass, the most abundant type of biomass and includes a wide variety of different biomass types including grasses, wood, energy crops, and agricultural and municipal wastes, is mostly composed of cellulose, hemicellulose, and lignin. Depolymerization of lignin, which is a phenolic polymer, can provide phenol. Solvents used in the production of monomers, such as methanol and acetone can be obtained from syngas, which is a product of the gasification of biomass. [0020] Poly(phenylene ether), such as a recycled poly(phenylene ether) comprising an open- or closed-loop post-consumer recycled (“PCR”) poly(phenylene ether), an open- or closed-loop post-industrial recycled (“PIR”) poly(phenylene ether), or upcycled poly(phenylene ether) or a combination thereof can be used, provided that the desired property or combination of properties can be achieved. As used herein, the term “post-consumer recycle poly(phenylene 23SHPP0032-WO-PCT (SS220061PCT) ether)” refers to a poly(phenylene ether) that has reached the intended user or consumer and which has been collected or reclaimed after utilization by the end-user or consumer. Thus, for example, it is understood that that the term refers to a poly(phenylene ether) material in whole or in part that would have otherwise been disposed of as waste, but has instead been collected and recovered (reclaimed) as a material input, in lieu of a virgin material, for a recycling or manufacturing process. PCR-poly(phenylene ether) is inclusive of material that has been reprocessed from collected or reclaimed material by means of a manufacturing process, (including e.g., purification, sorting, and pretreating) and made into a product or into a component for incorporation into a product. Such recycled poly(phenylene ether)s can be further processed, for example, into the form of powders, ground materials, flakes, pellets, or other form. As used herein, the term “post-industrial recycled poly(phenylene ether)” refers to a poly(phenylene ether) polymer or polymers that have never reached the end user and that is production waste arising during polymerization reactions, during further processing, or during manufacturing the resin or an article and includes materials such as, but not limited to, sprues from injection molding, start-up material from injection molding or extrusion, extrusion scrap, molding scrap, edge trims from extruded sheets or films, and the like, including materials diverted from the waste stream during a manufacturing process for an article. [0021] The poly(phenylene ether) can be present in the foamed material in an amount of 5 to 49.9 weight percent, based on the total weight of the foamed material. Within this range, the poly(phenylene ether) can be present in an amount of at least 10 weight percent, or at least 15 weight percent, or at least 20 weight percent, or at least 25 weight percent. Also within this range, the poly(phenylene ether) can be present in an amount of at most 45 weight percent, or at most 40 weight percent, or at most 35 weight percent, or at most 34.9 weight percent. For example, in an aspect, the poly(phenylene ether) can be present in an amount of 25 to 34.9 weight percent, based on the total weight of the foamed material. In another aspect, the poly(phenylene ether) can be present in an amount of 5 to 40 weight percent, based on the total weight of the foamed material. [0022] In addition to the polystyrene and the poly(phenylene ether), the foamed material comprises a nucleating agent. Without wishing to be bound by theory, it is believed that inclusion of a nucleating agent can provide an improved foam structure, and therefore can contribute to the foamed materials exhibiting the desired combination of properties. Suitable nucleating agents are not particularly limited and can comprise, for example, CaCO₃ (chalk), talc, carbon black, graphite, titanium dioxide, a polymeric nucleating agent, or a combination thereof. In a specific aspect, the nucleating agent can comprise talc 23SHPP0032-WO-PCT (SS220061PCT) [0023] . However, the inventors hereof have found that specific nucleating agents, or a combination of specific nucleating agents and specific blowing agents as described in further detail below can provide unexpected advantages. Thus, in an aspect, the nucleating agent can comprise a nanostructured nucleating agent, preferably a nanostructured polymer-based nucleating agent. As used herein, the term “nanostructured” refers to a material in which one dimension of the material is equal to or less than 1000 nanometer (nm) (e.g., one dimension is 1 to 1000 nm in size). In a particular aspect, the nanostructure includes at least two dimensions that are equal to or less than 1000 nm (e.g., a first dimension is 1 to 1000 nm in size and a second dimension is 1 to 1000 nm in size). In another aspect, the nanostructure includes three dimensions that are equal to or less than 1000 nm (e.g., a first dimension is 1 to 1000 nm in size, a second dimension is 1 to 1000 nm in size, and a third dimension is 1 to 1000 nm in size). The shape of the nanostructure can be of a wire, a particle (e.g., having a substantially spherical shape), a rod, a tetrapod, a hyper-branched structure, a tube, a cube, or a combination thereof. The nanostructures can be monodisperse, having particles of uniform size, or where all particles are of the same size with little variation, or polydisperse, where the particles have a range of sizes and are averaged. The nanostructured nucleating agents can be as described in U.S. Publication No.2023/0020844. [0024] The nucleating agent can be present in the foamed material in an amount of 0.1 to 5 weight percent, based on the total weight of the foamed material. Within this range, the nucleating agent can be present in an amount of 0.1 to 4 weight percent, or 0.1 to 3 weight percent, or 0.1 to 2 weight percent, or 0.1 to 1 weight percent, or 1 to 4 weight percent, or 1 to 3 weight percent or 2 to 3 weight percent, each based on the total weight of the foamed material. [0025] In addition to the polystyrene, the poly(phenylene ether), and the nucleating agent, the foamed material can optionally further comprise an organophosphate ester flame retardant, preferably an aromatic organophosphate ester flame retardant that is not halogenated. Exemplary organophosphate ester flame retardants, in particular aromatic, halogen-free organophosphate ester flame retardants can include phosphate esters comprising phenyl groups, substituted phenyl groups, or a combination of phenyl groups and substituted phenyl groups, bis-aryl phosphate esters based upon resorcinol such as, for example, resorcinol bis(diphenyl phosphate), as well as those based upon bisphenols such as, for example, bisphenol A bis(diphenyl phosphate). In an aspect, the organophosphate ester is a tris((C_1-6alkyl)phenyl) phosphate (for example, CAS Reg. No.89492-23-9 or CAS Reg. No.78-33-1), resorcinol bis(diphenyl phosphate) (CAS Reg. No.57583-54-7), bisphenol A bis(diphenyl phosphate) (CAS Reg. No.181028-79-5), triphenyl phosphate (CAS Reg. No.115-86-6), 23SHPP0032-WO-PCT (SS220061PCT) tris(isopropylphenyl) phosphate (for example, CAS Reg. No.68937-41-7), t-butylphenyl diphenyl phosphate (CAS Reg. No.56803-37-3), bis(t-butylphenyl) phenyl phosphate (CAS Reg. No.65652-41-7), tris(t-butylphenyl) phosphate (CAS Reg. No.78-33-1), or a combination thereof. In an aspect, the organophosphate ester comprises bisphenol A bis(diphenyl phosphate). [0026] When present, the organophosphate ester flame retardant can be present in the foamed material in an amount of 0.5 to 20 weight percent, based on the total weight of the foamed material. Within this range, the organophosphate ester flame retardant can be present in an amount of 1 to 20 weight percent, or 1 to 18 weight percent, or 1 to 15 weight percent, or 1 to 12 weight percent, or 1 to 10 weight percent, each based on the total weight of the foamed material. [0027] The foamed material can, optionally, minimize or exclude components other than those described herein as required. The foamed material excludes a block copolymer of an alkenyl aromatic and a conjugated diene. In an aspect, the foamed material comprises less than or equal to 0.5 weight percent, or entirely excludes, polyamides. As another example, in an aspect, the foamed material comprises less than or equal to 0.5 weight percent, or entirely excludes, polyolefins. As another example, in an aspect, the foamed material comprises less than or equal to 0.5 weight percent, or entirely excludes, impact modifiers such as rubber- modified polystyrene. As another example, the blowing agent used to form the foamed material excludes halogenated blowing agents. In an aspect, the composition can exclude or minimize (i.e.,, include less than 5 weight percent, or less than 1 weight percent, or less than 0.1 weight percent, or no) thermoplastic polymers other than the poly(phenylene ether) and the polystyrene. In an aspect, the foamed material can minimize or exclude a coupling agent (e.g., a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, or a combination thereof), a dispersant (e.g., a polyolefin-based hyperdispersant, a polyether-based hyperdispersant, a polyacrylate-based hyperdispersant, or a combination thereof) and deodorant (e.g., comprising hydrotalcite or silica), or a combination thereof. In an aspect, a flame retardant other than the organophosphate ester flame retardant can be present in an amount of less than 1 weight percent, or less than 0.5 weight percent, or less than 0.1 weight percent, or is preferably excluded from the foamed material. In an aspect, a halogenated flame retardant is excluded from the foamed material. [0028] One advantage of the foamed material is that it can exhibit good flame retardancy without using substantial amounts, or any halogenated flame retardants. In an aspect, the foamed material further excludes any halogenated component. For example, in an aspect the 23SHPP0032-WO-PCT (SS220061PCT) foamed material comprises less than or equal to 1,500 parts per million by weight total of chlorine, bromine, fluorine, and iodine, based on the total weight of the foamed material. [0029] In a specific aspect, the foamed material can comprise 65 to 74.9 weight percent of polystyrene; 25 to 34.9 weight percent of the poly(phenylene ether); 0.1 to 3 weight percent of the nucleating agent; wherein weight percent is based on the total weight of the foamed material. In another specific aspect, the foamed material can comprise 50 to 93.9 weight percent of polystyrene; 5 to 40 weight percent of the poly(phenylene ether); 1 to 10 weight percent of the organophosphate ester flame retardant; 0.1 to 3 weight percent of the nucleating agent; and wherein weight percent is based on the total weight of the foamed material. The poly(phenylene ether) can be a poly(2,6-dimethyl-1,4-phenylene ether) homopolymer and have an intrinsic viscosity of 0.2 to 1 deciliter per gram, preferably 0.4 to 0.6 deciliters per gram, measured at 25 °C in chloroform by Ubbelohde viscometer. The polystyrene can comprise an atactic homopolystyrene having a melt flow index of 1.5 to 15 grams per 10 minutes, measured at 200 °C and 5 kilogram load according to ASTM D1238-13. The organophosphate ester, when present, can comprise bisphenol A bis(diphenyl phosphate). The nucleating agent can comprise talc or a polymeric nanostructured nucleating agent. The foamed material can comprise less than or equal to 1,500 parts per million by weight total of chlorine, bromine, fluorine, and iodine, based on the total weight of the foamed material. [0030] The foamed material can optionally further comprise one or more additives, provided that the additive(s) do not significantly adversely affect a desired property of the foamed material, for example flame retardancy, compression strength, or tensile properties. The additive composition or individual additives can be mixed at a suitable time during the mixing of the components for forming the foamed material. The additive composition can include flow modifier, filler (e.g., a particulate polytetrafluoroethylene (PTFE), glass, carbon, mineral, or metal, although in an aspect a particulate PTFE is excluded), antioxidant, heat stabilizer, light stabilizer, ultraviolet (UV) light stabilizer, UV absorbing additive, plasticizer, lubricant, release agent (such as a mold release agent), antistatic agent, anti-fog agent, antimicrobial agent, colorant (e.g., a dye or pigment), surface effect additive, radiation stabilizer, anti-drip agent (e.g., a PTFE-encapsulated styrene-acrylonitrile copolymer (TSAN), although in an aspect TSAN is excluded), or a combination thereof. The additives are used in the amounts generally known to be effective. For example, the total amount of the additive composition (other than any impact modifier, filler, or reinforcing agent) can be 0.001 to 10 weight percent, or 0.1 to 10 weight percent, or 0.01 to 5 weight percent, each based on the total weight of the polymer in the 23SHPP0032-WO-PCT (SS220061PCT) foamed material. In an aspect the foamed material can exclude additives not specifically disclosed herein. [0031] The foamed material has a density of 20 to 100 kilograms per cubic meter, measured at 23°C. Within this range, the density can be 30 to 100 kilograms per cubic meter, or 40 to 90 kilograms per cubic meter, or 40 to 75 kilograms per cubic meter, or 40 to 65 kilograms per cubic meter. [0032] Advantageously, the foamed material can exhibit a closed cell content of greater than 90%. Within this range, the closed cell content can be, for example, greater than 90 to 99%, or 91 to 99%, or 91 to 98%, or 92 to 98%. The foamed material can further have a number average cell size of 100 to 600 micrometers. Within this range, the number average cell size can be, for example, 150 to 550 micrometers, or 200 to 500 micrometers, or 250 to 500 micrometers. In a specific aspect, the number average cell size can be in the range of 200 to 300 micrometers. [0033] The foamed material can exhibit a desirable combination of one or more properties. For example, the foamed material can exhibit a compression strength of greater than 0.35 N/mm², preferably greater than 0.35 to less than 1 N/mm². In an aspect, the foamed material can exhibit a tensile strength of greater than 0.85 MPa, or greater than 0.9 MPa, for example 0.9 to 1.5 MPa, or 0.9 to 1.3 MPa. In an aspect, the foamed material can exhibit one or both of a burning rate of less than 100 millimeters per second at a thickness of 6 millimeters according to FMVSS test standard, or a HF1 rating at a thickness of 6 millimeters according to ISO9772, particularly when an aromatic, non-halogenated flame retardant is present in the composition. In an aspect, the foamed materials can exhibit good dielectric stability. For example, the dielectric constant (Dk) and dissipation factor (Df) can remain stable over a range of frequencies, for example over the range of 58 to 88 GHz. As used herein, a stable dielectric constant (Dk) can refer to a change of less than 0.2 in the dielectric constant over the recited frequency range. As used herein, a stable dissipation factor can refer to a change of less than 0.02 in the dissipation factor over the recited frequency range. As further described and illustrated herein these combinations can provide an optimal balance of mechanical properties and flame performance versus compositions of the prior art. This combination can further be achieved using a much lower amount of poly(phenylene ether) and flame retardant. [0034] In a specific aspect, the foamed material can comprise 67 to 72 weight percent of polystyrene; 28 to 32 weight percent of the poly(phenylene ether); and 2.5 to 3.5 weight percent of the nucleating agent; wherein weight percent is based on the total weight of the foamed material. The poly(phenylene ether) can be a poly(2,6-dimethyl-1,4-phenylene ether) homopolymer and have an intrinsic viscosity of 0.2 to 1 deciliter per gram, preferably 0.4 to 0.6 23SHPP0032-WO-PCT (SS220061PCT) deciliters per gram, measured at 25 °C in chloroform by Ubbelohde viscometer. The polystyrene can comprise an atactic homopolystyrene having a melt flow index of 1.5 to 15 grams per 10 minutes, measured at 200 °C and 5 kilogram load according to ASTM D1238-13. The nucleating agent comprises a polymeric nanostructured nucleating agent, preferably a nanostructured nucleating agent comprising a fluoropolymer. The foamed material can comprise less than or equal to 1,500 parts per million by weight total of chlorine, bromine, fluorine, and iodine, based on the total weight of the foamed material. The foamed material can have a density of 40 to 60 kg/m³, a closed cell content of greater than 96%, for example greater than 96 to 99%, a number average cell size of 200 to 210 micrometers, and a specific compression of greater than or equal to 0.01 MPa, for example 0.01 to 0.015 MPa. The foamed material can have a tensile strength of greater than 1 MPa, for example greater than 1 to 1.5 MPa. [0035] In a specific aspect, the foamed material can comprise 67 to 72 weight percent of polystyrene; 28 to 32 weight percent of the poly(phenylene ether); and 0.1 to 1 weight percent of the nucleating agent; wherein weight percent is based on the total weight of the foamed material. The poly(phenylene ether) can be a poly(2,6-dimethyl-1,4-phenylene ether) homopolymer and have an intrinsic viscosity of 0.2 to 1 deciliter per gram, preferably 0.4 to 0.6 deciliters per gram, measured at 25 °C in chloroform by Ubbelohde viscometer. The polystyrene can comprise an atactic homopolystyrene having a melt flow index of 1.5 to 15 grams per 10 minutes, measured at 200 °C and 5 kilogram load according to ASTM D1238-13. The nucleating agent comprises talc. The foamed material can comprise less than or equal to 1,500 parts per million by weight total of chlorine, bromine, fluorine, and iodine, based on the total weight of the foamed material. The foamed material can have a density of 60 to 70 kg/m³, a closed cell content of greater than 96%, for example greater than 96 to 99%, a number average cell size of 285 to 295 micrometers, and a specific compression of greater than or equal to 0.01 MPa, for example 0.01 to 0.015 MPa. [0036] Another aspect of the present disclosure is a method of making the foamed material. In an aspect, the method comprises melt blending in an extruder components of any one of the foamed compositions described herein, i.e., the polystyrene; the poly(phenylene ether); the nucleating agent; and optionally, the organophosphate ester flame retardant, preferably a halogen-free, aromatic organophosphate ester flame retardant, to form a molten thermoplastic composition; adding a blowing agent to the extruder to form a pre-foamed molten thermoplastic composition; and extruding the pre-foamed molten thermoplastic composition from the extruder to form the foamed material. For example, the method comprises melt blending in an extruder components comprising, based on the total weight of the foamed 23SHPP0032-WO-PCT (SS220061PCT) material, 50 to 94.9 weight percent of polystyrene; 5 to 49.9 weight percent of a poly(phenylene ether); 0.1 to 5 weight percent of a nucleating agent; and optionally, 1 to 20 weight percent of an organophosphate ester flame retardant to form a molten thermoplastic composition; adding a blowing agent to the extruder to form a pre-foamed molten thermoplastic composition; and extruding the pre-foamed molten thermoplastic composition from the extruder to form the foamed material. In an aspect, the foamed material is not prepared by a blow molding process. [0037] In an aspect, at least a portion of the compositions of the pre-foamed molten thermoplastic composition can be provided in the form of a masterbatch. For example, a method of making the foamed material can comprise melt blending a first portion of polystyrene, the poly(phenylene ether), and optionally, the organophosphate ester flame retardant to provide a masterbatch. The method further comprises melt blending in an extruder the masterbatch, a second portion of polystyrene, and the nucleating agent to form a molten thermoplastic composition; adding a blowing agent to the extruder to form a pre-foamed molten thermoplastic composition; and extruding the pre-foamed molten thermoplastic composition from the extruder to form the foamed material. [0038] In an aspect, the masterbatch can comprise 20 to 55 weight percent of the first portion of polystyrene; 45 to 65 weight percent of the poly(phenylene ether); and optionally, 5 to 20 weight percent of the organophosphate ester flame retardant; wherein weight percent is based on the total weight of the masterbatch. [0039] The term “blowing agent” as used herein refers to a chemical agent that is used to foam a polymer. The blowing agent, also referred to herein as a foaming agent, can be a solid, a liquid, and/or a supercritical liquid. Suitable blowing agents that can be used include inorganic agents, organic agents, and other chemical agents. Exemplary inorganic blowing agents include carbon dioxide, nitrogen, argon, water, air, nitrogen, and inert gases (such as helium and argon), or a combination thereof. Exemplary organic agents include aliphatic hydrocarbons having 1-9 carbon atoms, aliphatic alcohols having 1-3 carbon atoms, and fully and partially halogenated aliphatic hydrocarbons having 1-4 carbon atoms. Aliphatic hydrocarbons include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, and the like. Aliphatic alcohols include methanol, ethanol, n-propanol, and isopropanol. Fully and partially halogenated aliphatic hydrocarbons include fluorocarbons, chlorocarbons, and chlorofluorocarbons. Examples of fluorocarbons include methyl fluoride, perfluoromethane, ethyl fluoride, 1,1- difluoroethane (HFC-152a), 1,1,1-trifluoroethane (HFC-143a), 1,1,1,2-tetrafluoro-ethane (HFC- 134a), pentafluoroethane, difluoromethane, perfluoroethane, 2,2-difluoropropane, 1,1,1- trifluoropropane, perfluoropropane, dichloropropane, difluoropropane, perfluorobutane, 23SHPP0032-WO-PCT (SS220061PCT) perfluorocyclobutane, and the like. Partially halogenated chlorocarbons and chlorofluorocarbons include methyl chloride, methylene chloride, ethyl chloride, 1,1,1-trichloroethane, 1,1-dichloro- 1-fluoroethane (HCFC-141b), 1-chloro-1,1-difluoroethane (HCFC-142b), chlorodifluoromethane (HCFC-22), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123), 1-chloro- 1,2,2,2-tetrafluoroethane (HCFC-124), and the like. Fully halogenated chlorofluorocarbons include trichloromonofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trichlorotrifluoroethane (CFC-113), 1,1,1-trifluoroethane, pentafluoroethane, dichlorotetrafluoroethane (CFC-114), chloroheptafluoropropane, and dichlorohexafluoropropane. Other chemical agents include azodicarbonamide, azodiisobutyronitrile, benzenesulfonhydrazide, 4,4-oxybenzene sulfonyl-semicarbazide, p- toluene sulfonyl semi-carbazide, barium azodicarboxylate, N,N^-dimethyl-N,N^- dinitrosoterephthalamide, trihydrazino triazine, and the like. In an aspect, the blowing agent can be carbon dioxide, air, nitrogen, argon, gaseous hydrocarbons, or a combination thereof. [0040] In an aspect, the blowing agent can comprise propane, cyclopentane, isopentane (2-methylbutane), n-pentane, n-butane, isobutane (2-methylpropane), neopentane, dimethyl ether, ethanol, carbon dioxide, or a combination thereof. In an aspect, the blowing agent does not include a supercritical liquid such as supercritical CO₂. In an aspect, the blowing agent is halogen-free, for example fluorine-free. [0041] The blowing agent is introduced to the extruder in an amount effective to provide a total amount of blowing agent of less than 6 weight percent of blowing agent, wherein weight percent of the blowing agent is based on the total weight of the poly(phenylene ether) and the polystyrene. For example, the blowing agent can be introduced in an amount effective to provide a total amount of blowing agent of 3 to less than 6 weight percent, or 4 to less than 6 weight percent, or 5 to less than 6 weight percent, or 5.1 to 5.9 weight percent, each based on the total weight of the poly(phenylene ether) and the polystyrene. [0042] The step of melt blending is conducted in an extruder, which can be, for example, a single-screw extruder, or a twin-screw extruder. The extruder can comprise independently heated zones, each of which can be operated a temperature of 20 to 340 °C. Detailed extrusion conditions are described in the working examples below. [0043] The foamed composition in the form of an extruded foam board. The foam board can have a width of, for example, 50 to 500 millimeters (mm), for example 100 to 300 mm, or 150 to 250 mm, and a thickness of 1 to 25 mm, for example 2 to 15 mm, or 5 to 10 mm. 23SHPP0032-WO-PCT (SS220061PCT) [0044] The foamed composition prepared by the method described herein has a density of 20 to 100 kilograms per cubic meter, measured at 23 °C, and a closed cell content of greater than 90%. [0045] All of the variations described above in the context of the foamed material apply as well to the method of making the foamed material. [0046] The foamed material described herein can be useful in a variety of articles. An article comprising the foamed composition therefore represents another aspect of the present disclosure. Exemplary articles can include extruded foam sheets, foam beads, injection-molded foam, composite laminates/ sandwich structures, foam insulation boards, building materials, an electric vehicle battery component, an electrical box component, an automotive component, or insulation for wire or cable. In a specific aspect, the article can be insulation, ceiling insulation, insulation for attics and crawl spaces, backing for exterior siding, interior trim, interior signs, plenums, refrigerator insulation, or freezer insulation. The foams can further be used in wind, aerospace, or transportation, or mass transportation applications, for example a component of as a train, a tram, a subway, a light rail, a monorail, an aircraft, a helicopter, a bus, a trolley, a ferry, a cable car, or the like. [0047] This disclosure is further illustrated by the following examples, which are non- limiting. EXAMPLES [0048] Materials used in the following examples are described in Table 1. Table 1 Component Description Supplier PPE Poly(2,6-dimethyl-1,4-phenylene ether), CAS Reg. No.25134-01-4, having an SABIC intrinsic viscosity of about 0.40 deciliter per gram measured in chloroform at 25° C PS Atactic polystyrene, CAS Reg . No .9003-53-6 , having no mineral oil content Total Energies and a melt flow index of 6-8 grams per 10 minutes measured at 200° C and 5 kilogram load; obtained as 1450N BPADP Bisphenol A bis(diphenyl phosphate), CAS Reg. No.181028-79-5 Adeka Br-PS MB Flame retardant masterbatch containing 40 weight percent HBCD-free flame Campine retardant additive in a polystyrene carrier, obtained as MASTERTEK 7405934 Nucleating Nanostructured nucleating agent in polystyrene SABIC Agent TalcMB Talc masterbatch containing 60 weight percent talc in a polystyrene carrier, Green Chemicals obtained as STARCELL^TM PS 60 CO₂ Carbon dioxide, CAS Reg. No.124-38-9 Linde EtOH Ethanol, CAS Reg. No.64-17-5 Theo Seulberger Chemie DME Dimethyl ether, CAS Reg. No.115-10-6 Gerling Holz, Co. iButane Isobutane, CAS Reg. No.75-28-5 Gerling Holz, Co. Pentane Pentane, CAS Reg. No.109-66-0 Theo Seulberger Chemie 23SHPP0032-WO-PCT (SS220061PCT) iPentane Isopentane, CAS Reg. No.78-78-4 Theo Seulberger Chemie cPentane Cyclopentane, CAS Reg. No.287-92-3 Theo Seulberger Chemie Propane Propane, CAS Reg. No.74-98-6 Linde [0049] Masterbatches of PPE and PS, optionally with flame retardant were prepared. Components of the compositions were dry blended and extruded with a ZSK 25 mm Coperion Werner and Pfleiderer 40 L/D co-rotating twin screw extruder with a vacuum vented mixing screw. The temperature settings during the compounding trials were: 40-180-210-220-260-260- 260-240-240-240 °C with a screw speed of 300 rpm at 10-20 kg/hr, unless otherwise noted. The extrudate was cooled with a water bath prior to pelletization. The resulting formulations were converted in ISO IZOD bars on an ENGEL 90 molding machine using the following process conditions: 2 hour pre-drying time; 80 °C pre-drying temperature; 60 °C hopper temperature; 270-290-300 °C zone 1-3 temperatures (respectively); 275 °C nozzle temperature; and 90 °C mold temperature. [0050] The masterbatch compositions were analyzed for Vicat softening temperature (VST) according to ISO306. Melt-volume flow rate (MVR) was determined in accordance with ISO1133 at 280°C under a 5 or a 2.16 kilogram load. [0051] Compositions and properties of the masterbatches are shown in Table 2. Table 2 Component Unit MB1 MB2 PPE wt% 50 60 PS wt% 50 25 BPADP wt% 15 P^roperties VST °C 145 124 MVR (280°C/5 kg) cm³/10 min 48 MVR (280°C/2.16 kg) cm³/10 min 17 [0052] Extruded foams were produced by a KraussMaffei Berstorf Schaumtandex laboratory unit ZE30/KE60 which includes a twin-screw extruder as a primary extruder (plastification, additivation and gas nucleation of the polymers) and a secondary single-screw extruder (for cooling and homogenizing the melt). The tandem extrusion line, both ZE and KE are 30L/D. ZE has 30 mm co-rotating twin screw, KE 60 mm single screw. The masterbatch (MB1 or MB2 from Table 2), PS, a nucleating agent, and a brominated FR (Br-PS MB at 1.5%) was continuously fed into the meltdown extruder. Blowing agents or propellants were injected into the injection port under pressure. The total throughput including the blowing agents and additives was about 25 kg/hr. The propellant-containing melt was cooled in a subsequent 23SHPP0032-WO-PCT (SS220061PCT) cooling extruder and extruded at a throughput of 30 kg/hr through a slot die. The intumescent melt was withdrawn through a heated belt and heated to a plate by means of a heated calibration, the surfaces of which are equipped with PTFE. Typical plate dimensions before mechanical processing were approximately 300 to 350 mm wide (y direction) and 20 to 40 mm thick (z direction). The foam extrusion processing parameters are shown in Tables 3 and 4. Haul-off unit line speed was 2.5-5 meters per minute (m/min). Table 3 ZE30 Pure PS foams MB1- based foams MB2- based foams °C °C °C Zone 0 40 39-41 39-40 Zone 1 56 56 56 Zone 2 134 133-139 133-135 Zone 3 270 273-280 263-272 Zone 4 276 280 270-280 Zone 5 181 229-231 230 Zone 6 180 230 230 Zone 7 180 230 220-231 P1 30-32 14-55 1-33 Pinj 80 80 80 P2 111-113 114-172 89-119 T1 52-53 60-65 54-59 T^{able 4} KE60 Pure PS foams MB1-based foams MB2-based foams °C °C °C Zone 10 80 80 80 Zone 11 125 144-145 125-145 Zone 12 89-90 85-90 89-90 Zone 13 180 190-194 179-190 Zone 14 138-140 146-151 135-151 Zone 15 100 137-141 119-140 Zone 16 100-101 137-142 115-141 Zone 17 100-100 137-142 114-142 Zone 18 112-113 139-143 121-140 Zone 19 100-101 137-141 113-136 Zone 20 106-109 140-141 123-146 Zone 21 100 138-140 115-140 Zone 21.1 160 160 160 Zone 21.2 161 161 161 Zone 22 80 115-120 100-120 Zone 23 80 80 80 50 P3 80 94-136 94-119 P4 53-54 37-54 34-38 T2 115-117 152-153 133-158 [0053] Exemplary compositions and particular foam extrusion processing conditions for each composition are shown in Table 5. Amounts of each component are shown in weight percent based on the total weight of the polymer components (i.e., PS + MB-1/MB-2). 23SHPP0032-WO-PCT (SS220061PCT) Specifically, Table 5 shows the throughput, torque, RPM, and specific energies for each composition. Table 5 Component Units CE1 CE2 Ex1 Ex2 Ex3 Ex4 Ex5 Ex6 PS wt% 100 100 39.5 39.5 39.5 39.5 39.5 39.5 MB-1 wt% 60 60 60 60 60 60 MB-2 wt% CO2 wt% 0.8 0.8 0.6 0.6 0.6 1 0.6 0.6 Ethanol wt% 3.5 3.5 3.5 3.5 3.5 4.5 3.5 3.5 DME wt% 1.5 1.5 1.5 1.5 1.5 Isobutane wt% 1.5 Pentane wt% Isopentane wt% 1.5 Cyclopentane wt% Propane wt% Br-PS MB wt% 1.5 TalcMB wt% 1 1 1 1 1 1 Nucleating Agent wt% 0.5 3 Foam Extrusion Conditions Throughput kg/hr 25/29.7 25/29.7 25/30 25/30 25/30 25/30 25/30 25/30 ZE30/KE60 Torque ZE30/KE60 % 31/29 32/29 30/37 30/38 31/38 36/42 33/40 33/41 Screw speed RPM 250/16.5 250/16.5 250/15 250/15 250/15 250/15 250/15 250/15 ZE30/KE60 Specific energy kWh/k 0.177/ 0.182/ 0.167/ 0.167/ 0.174/ 0.20/ 0.186/ 0.187/ ZE30/KE60 g 0.067 0.067 0.079 0.08 0.08 0.09 0.086 0.088 Table 5 (continued) Components Units Ex7 Ex8 Ex9 Ex10 Ex11 Ex12 Ex13 Ex14 PS wt% 39.5 39.5 39.5 90 80 60 40 40 MB-1 wt% 60 60 60 MB-2 wt% 10 20 40 60 60 CO2 wt% 0.6 0.6 1 1 1 1 1 1 Ethanol wt% 3.5 3.5 4.5 4.5 4.5 4.5 4.5 DME wt% Isobutane wt% Pentane wt% 4 Isopentane wt% Cyclopentane wt% 1.5 Propane wt% 1.5 Br-PS MB wt% TalcMB wt% 1 1 1 1 1 1 1 Nucleating Agent wt% 1 Throughput kg/hr 25/30 25/30 25/29.8 25/30 25/30 25/30 25/30 25/30 ZE30/KE60 Torque ZE30/KE60 % 33/42 35/39 41/46 33/38 31/29 27/32 28/37 26/37 Screw speed RPM 250/15 250/15 250/14.9 250/15 250/15 250/15 250/15 250/15 ZE30/KE60 Specific energy kWh/k 0.188/ 0.98/ 0.228/ 0.186/ 0.175/ 0.153/ 0.158/ 0.149/ ZE30/KE60 g 0.090 0.083 0.098 0.08 0.062 0.068 0.078 0.078 23SHPP0032-WO-PCT (SS220061PCT) [0054] The foamed samples of Table 5 were examined for various properties characterization, including visual appearance, density, closed cell content, cell size, call aspect ratio, cell wall thickness, compression strength, tensile strength, bending stiffness, thermal stability, thermal conductivity (^), dielectric stability Dk/Df and flame retardancy. Test methods and testing conditions are summarized in Table 6. Table 6 Property Test Standard Foam visual appearance Foam Density ASTM D792 Closed cell content EN13164 Cell size (Number average CT Scan Cell size (Volume average) CT Scan Cell aspect ratio (Number average) CT Scan Cell aspect ratio (Volume average) CT Scan Cell Wall thickness CT Scan Initial Compression Strength Compression Strength after 45 days ISO844 E-Moduli (MPa) Tensile strength (tested by elongation of samples) EN1607 (EN13164) Bending Stiffness EN12089 [2] Water immersion DIN EN12087 FR Testing FMVSS302 FR Testing UL HBF/ISO9772 FR Testing EN11925-2:2020 Thermal stability Foams 100 x 100 mm are put in oven at 100C/ 4 weeks. Dimensions LxBxH measured before and after oven ageing Dielectric stability 58 to 88 GHz (Dk/Df) Determined using Rohde & Schwarts ZVA50 / ZVA-Z90 frequency converter / Swissto12 WR-12+ waveguide [0055] Thermal conductivity (^) was measured by heat flow meter LaserComp FOX 50 from TA instruments. Thermal stability was assessed by placing foams having dimensions of 100 x 100 mm in oven at 100 °C for 4 weeks. Dimensions (LxWxH) were measured before and after oven ageing. [0056] For flame testing, the foamed compositions were cut into 6 millimeter thickness bars for flammability testing according to ISO 9772, a horizontal burn test for foamed materials. This flammability test rates performance in the following manner: non-classified (NC) which is the worst flaming behavior, medium flame retardant performance (HBF), and superior flame retardant performance (HF1) and somewhat less superior (HF2). Superior flame retardant performance HF1 is defined as short flame out times and non-dripping behavior, while less superior HF2 should meet similar criteria as HF1 but dripping is allowed. [0057] The foamed compositions were also tested for flammability according to the test method Federal Motor Vehicle Safety Standards (FMVSS) at 6 millimeter thickness, which are 23SHPP0032-WO-PCT (SS220061PCT) U.S. federal regulations. Standard FMVSS 302 relates to the burning behavior of materials used inside road vehicles such as passenger cars, trucks, buses, and agriculture machinery. The test sample is held horizontally in a U-shaped holder and exposed to a flame for 15 seconds in a combustion chamber, in order to see if/when the flame extinguishes, or the time taken for the flame to pass a defined distance. The burning rate per minute is then calculated. For most automotive applications, a burning rate of no more than 100 mm/min is acceptable. [0058] Flame retardancy testing was also conducted according to EN ISO 11925-:2010. EN ISO 11925-2:2010 is the principal flame standard in Europe to classify materials for building applications. It is the generally accepted flame standard for construction materials for walls and ceilings (but not floorings). [0059] The dimensions of the test specimens were 250x90x20 millimeters. The test specimens were cut to size from larger boards. The surface of the foam plates were not ideally flat as there was no calibrator used during the foam extrusion. To account for variations in dimensions, six samples per foam material were used for each of the surface and edge flame applications. [0060] To conduct each test, a foam specimen was clamped in vertical position and subjected to a small propane flame for 15 seconds. The flame was applied both on the surface of the foam plate (6 tests) and on the edge of the foam plate (6 tests). The sample was marked 150 millimeters above the point where the flame was applied. After the 15 seconds of flame application the burner was removed from the sample and the specimens are observed for flame spread and the formation of flaming drips that potentially are formed from the foam sample and might ignite the paper positioned below the sample. [0061] The criteria for a Class E rating are that the flame should not pass the 150 millimeter mark line and the paper positioned below the foam sample should not ignite by drips falling from the foam sample. These pass criteria apply to each individual test, 6 for surface testing and 6 for edge testing. The reported maximum flame height (in millimeters) and after burning time (in seconds) are not part of the test criteria but give additional details on the flaming behavior of the samples. [0062] The results, presented in Tables 7 and 9, show that the inventive foams of Examples 4 and 13-18 passed the EN ISO 11925-2:2010 test for a Class E rating under both surface and edge test conditions. In other words, none of the samples exhibited flame spread across the 150 millimeter mark and none of the samples exhibited ignition of the paper below the flame test set up. [0063] Results are shown in Table 7. 23SHPP0032-WO-PCT (SS220061PCT) Table 7 Properties Units CE1 CE2 Ex1 Ex2 Ex3 Ex4 Ex5 Ex6 Visual appearance Good Good Good Good Good Good Good Good Density kg/m³ 42 47.8 51.9 49.6 51.1 51 48.8 53 Closed cell content % 94.8 97.88 97.19 96.69 Cell size (number µm 397 322 372 205 291 277 315 average) Cell size (volume µm 449 372 428 233 338 310 380 average) Cell aspect ratio 1.51 1.37 1.43 1.4 1.49 1.37 2.76 (number average) Cell aspect ratio 1.47 1.32 1.39 1.37 1.44 1.34 3.08 (volume average) Cell Wall thickness µm 1.95 2.17 2.12 1.67 2.09 1.94 1.89 Initial Compression mW/mK 0.261 0.267 0.363 0.317 0.48 0.388 0.352 0.361 Strength Compression N/mm² 0.34 0.363 0.455 0.413 0.586 0.518 0.5 0.514 Strength, 45 days (MPa) Specific Compression MPa- 0.008095 0.0075940.008767 0.008327 0.011468 0.010157 0.010246 0.009698 strength, 45 days m³/kg Tensile strength MPa 0.76 1.25 1.08 1.12 E-Moduli (MPa) N/mm² 12.9 13.9 9.2 9.4 16.9 12.2 10.3 16.7 Initial ^ mW/mK 32.7 32.7 33.6 33.4 33.3 34.6 31 33.2 ^, 90 days mW/mK 33.7 33.9 34.5 34.8 34.2 34.7 32.9 35.3 Bending stiffness MPa 1.37 1.62 1.74 Water uptake % 0.66 FR Testing FMVSS; mm/s 123.9 0 129.7 143 Average burn rate (Fail) (Pass) (Fail) (Fail) FR Testing ISO9772; HF1 Fail Fail Fail Fail 6 mm rating (HBF- (HF2) (HBF- (HBF- NOT) NOT) NOT) Thermal stability Poor Poor Good Good Good Good Good Good 100°C/4 weeks Dielectric Stability Could Stable Stable Stable Stable Stable Stable Stable Dk and Df; 58-88 not be GHz measured FR Testing Fail Pass Pass EN11925-2:2010 Table 7 (cont.) Properties Units Ex7 Ex8 Ex9 Ex10 Ex11 Ex12 Ex13 Ex14 Visual appearance Good Good Good Good Good Good Good Good Density kg/m³ 48.2 45.1 64.8 49.1 42.9 43.2 45 45.3 Closed cell content % 93.33 94.71 97.05 91.9 93.19 Cell size (number µm 384 288 291 429 311 average) Cell size (volume µm 467 335 341 524 370 average) Cell aspect ratio 1.44 1.39 1.66 1.45 1.39 (number average) Cell aspect ratio 1.38 1.36 1.61 1.36 1.33 (volume average) Cell Wall thickness µm 2.28 1.63 2.2 2.28 1.98 Initial Compression mW/mK 0.314 0.332 0.589 0.352 0.285 0.23 0.237 0.262 Strength Compression N/mm² 0.457 0.457 0.663 0.467 0.405 0.376 0.357 0.397 Strength, 45 days (MPa) 23SHPP0032-WO-PCT (SS220061PCT) Specific Compression MPa- 0.0094810.0101330.0102310.0095110.0094410.0087040.0079330.008764 strength, 45 days m³/kg Tensile strength MPa 1.13 0.98 0.97 0.94 1.04 E-Moduli (MPa) N/mm² 15.9 15.1 27.4 11.2 10.4 11.5 8.3 12.3 (MPa) Initial ^ mW/mK 32.8 31.8 30.6 35.5 34.3 34.5 34.3 33.8 ^, 90 days mW/mK 34.8 33.6 33.2 36.1 35.8 34.9 35.2 34.4 Bending stiffness MPa 2.57 1.48 1.58 Water uptake % 0.47 FR Testing FMVSS; mm/s 138.7 0 (Pass) 0 (Pass) Average burn rate (Fail) FR Testing ISO9772; HF1 Fail Pass Pass 6 mm rating (HBF- (HF1) (HF1) NOT) Thermal stability Good Good Good Good Good Good Good Good 100°C/4 weeks Dielectric Stability Dk Stable Stable Stable Stable Stable Stable Stable Stable and Df; 58-88 GHz FR Testing EN11925- Fail Pass Pass 2:2010 [0064] As shown in Table 7, foams prepared according to the present disclosure exhibited a desirable combination of properties. In particular, foams according to the present disclosure exhibited improved compression strength, tensile strength, bending stiffness, and thermal stability compared to comparative polystyrene foams CE1 and CE2. The foams according to E1-14 each exhibited a high closed cell content (e.g., >90%). Use of the MB-1 or MB-2 also resulted in higher specific compression strength, with a 3-51% improvement compared to polystyrene extruded foams. [0065] Even with different blowing agent types or ratios, the similar higher specific compression strength improvement was observed, as in Ex4 to Ex12 and Ex14. It is further noted that Ex4 to Ex5 and Ex 8 to Ex9 have significantly improved compression strength using a variety of blowing agents than CEx1 (or even Ex 1) although the nucleating agent (talc) is same. [0066] Use of a nanostructured nucleating agent is further advantageous relative to talc, in that Ex3 with a nanostructured nucleating agent shows significantly higher compression and tensile strength compared to Ex1 (talc) or CE 1-2 (talc). The blowing agents used in Ex1 to Ex3 are similar, as are the blowing agents in Ex15 to Ex 18 and Ex10 to Ex14. Cell sizes using the nanostructured nucleating agents are significantly smaller as well. [0067] One or more desirable properties, for example improved compression strength, tensile strength, bending stiffness, thermal stability, or a combination thereof were obtained without use of a halogenated blowing agent. One or more desirable properties, for example improved compression strength, tensile strength, bending stiffness, thermal stability, or a 23SHPP0032-WO-PCT (SS220061PCT) combination thereof were obtained without use of a halogenated blowing agent and in the presence of a nanostructured or talc nucleating agent. When talc is used as a nucleating agent, the compositions are halogen-free, and in particular contain no added perfluoroalkyl substances (PFAS). In an aspect, the compositions have no intentionally added PFAS, thereby qualifying as “no intentionally added perfluoroalkyl substances” or NIA-PFAS. In an aspect, the compositions include less than or equal to 1,500 parts per million by weight total of fluorine, based on the total weight of the composition. [0068] Additional Examples were prepared as described above, as shown in Table 8. Table 8 Ex15 Ex16 Ex17 Ex18 PS wt% 40 39 38.7 38.2 MB-1 wt% MB-2 wt% 60 60 59.3 58.8 CO₂ wt% 2 2 2 2 Ethanol wt% 3.5 3.5 3.5 3.5 DME wt% Isobutane wt% Pentane wt% Isopentane wt% Cyclopentane wt% Propane wt% Br-PS MB wt% TalcMB wt% Nucleating Agent wt% 1 1 2 3 Throughput kg/hr 25/30 25/30 25/30 25/30 ZE30/KE60 Torque ZE30/KE60 % 31/42 32/47 33/45 33/45 Screw speed RPM 250/15 250/15 250/15 250/15 ZE30/KE60 Specific energy kWh/ 0.177/0.089 0.182/0.1 0.184/0.095 0.184/0.095 ZE30/KE60 kg [0069] The foams were tested as described above. Results are shown in Table 9. Table 9. Properties Units Ex15 Ex16 Ex17 Ex18 Visual appearance Good Good Good Good Density kg/m³ 53.98 53.76 53.11 53.74 Closed cell content % 95.9 97.7 97.7 99.2 Cell size (number µm ~1.4 1.82 average) Cell size (volume µm .31,3 1.84 average) Cell aspect ratio 350 116 (number average) Cell aspect ratio 400 134 (volume average) Cell Wall thickness µm 1.36 Compression N/mm² 0.511 0.65 0.732 0.751 Strength, 45 days (MPa) 23SHPP0032-WO-PCT (SS220061PCT) Specific Compression MPa- 0.009 0.0121 0.0138 0.0140 strength, 45 days m³/kg Initial ^ mW/mK 34.1 33.8 34.1 34.1 ^, 90 days mW/mK 24.5 34.1 34.1 34.1 FR Testing FMVSS; mm/s Pass Pass Pass Pass Average burn rate FR Testing ISO9772; HF1 HF1 HF1 HF1 HF1 6 mm rating Thermal stability Good Good Good Good 100°C/4 weeks Dielectric Stability Dk Stable Stable Stable Stable and Df; 58-88 GHz FR Testing EN11925- Pass Pass Pass Pass 2:2010 [0070] As shown in Table 9, foams prepared according to the present disclosure exhibited desirable properties, including a desirable combination of two or more properties. In particular, foams according to the present disclosure exhibited improved compression strength, tensile strength, bending stiffness, and thermal stability compared to polystyrene foams not according to the present disclosure (e.g., CE1 and CE2). The foams according to Ex15 to Ex18 each exhibited a high closed cell content (e.g., >90%). Use of the MB-1 or MB-2 also resulted in higher specific compression strength, with a 3-51% improvement compared to polystyrene extruded foams (see, e.g., Ex15 to Ex18 versus CEx2). [0071] One or more desirable properties, for example improved compression strength, tensile strength, bending stiffness, thermal stability, or a combination thereof were obtained without use of a halogenated blowing agent. One or more desirable properties, for example improved compression strength, tensile strength, bending stiffness, thermal stability, or a combination thereof were obtained without use of a halogenated blowing agent and in the presence of a nanostructured or talc nucleating agent. If talc is used as a nucleating agent, the compositions can be halogen-free, and in particular can contain no added perfluoroalkyl substances (PFAS). [0072] A significant improvement is therefore provided by the present disclosure. [0073] This disclosure further encompasses the following aspects. [0074] Aspect 1: An extruded foamed material comprising: 50 to 94.9 weight percent of polystyrene; 5 to 49.9 weight percent of a poly(phenylene ether); 0.1 to 5 weight percent of a nucleating agent; and optionally, 0.5 to 20 weight percent of an organophosphate ester flame retardant; wherein weight percent is based on the total weight of the foamed material; wherein the foamed material has a density of 20 to 100 kilograms per cubic meter, measured at 23 °C; a 23SHPP0032-WO-PCT (SS220061PCT) closed cell content of greater than 90%; and wherein a block copolymer of an alkenyl aromatic and a conjugated diene is excluded from the composition. [0075] Aspect 2: The foamed material of aspect 1, wherein the foamed material exhibits: a compression strength of greater than 0.35 N/mm², preferably greater than 0.35 to less than 1 N/mm²; or at least one of a burning rate of less than 100 millimeters per second at a thickness of 6 millimeters according to FMVSS test standard, or a HF1 rating at a thickness of 6 millimeters according to ISO9772. [0076] Aspect 3: The foamed material of aspect 1 or 2, wherein the foamed material is the product of a process comprising: melt blending a first portion of polystyrene; the poly(phenylene ether); and optionally, the organophosphate ester flame retardant, to provide a masterbatch; melt blending in an extruder the masterbatch, a second portion of polystyrene, and the nucleating agent to form a molten thermoplastic composition; adding a blowing agent to the extruder to form a pre-foamed molten thermoplastic composition; and extruding the pre-foamed molten thermoplastic composition from the extruder to form the foamed material. [0077] Aspect 4: The foamed material of any one of aspects 1 to 3, wherein the foamed material has a number average cell size of 100 to 600 micrometers. [0078] Aspect 5: The foamed material of any one of aspects 1 to 4, wherein the poly(phenylene ether) has an intrinsic viscosity of 0.2 to 1 deciliter per gram, preferably 0.4 to 0.6 deciliters per gram, measured at 25 °C in chloroform by Ubbelohde viscometer. [0079] Aspect 6: The foamed material of any one of aspects 1 to 5, wherein the polystyrene comprises an atactic homopolystyrene having a melt flow index of 1.5 to 15 grams per 10 minutes, measured at 200 °C and 5 kilogram load according to ASTM D1238-13. [0080] Aspect 7: The foamed material of any one of aspects 1 to 6, wherein the organophosphate ester flame retardant comprises bisphenol A bis(diphenyl phosphate). [0081] Aspect 8: The foamed material of any one of aspects 1 to 7, wherein a high impact polystyrene is excluded from the composition. [0082] Aspect 9: The foamed material of aspect 1, wherein the poly(phenylene ether) has an intrinsic viscosity of 0.2 to 1 deciliter per gram, preferably 0.4 to 0.6 deciliters per gram, measured at 25 °C in chloroform by Ubbelohde viscometer; wherein the polystyrene comprises an atactic homopolystyrene having a melt flow index of 1.5 to 15 grams per 10 minutes, measured at 200 °C and 5 kilogram load according to ASTM D1238-13; wherein the organophosphate ester comprises bisphenol A bis(diphenyl phosphate); wherein the nucleating agent comprises talc; and wherein the foamed material comprises less than or equal to 1,500 23SHPP0032-WO-PCT (SS220061PCT) parts per million by weight total of chlorine, bromine, fluorine, and iodine, based on the total weight of the foamed material. [0083] Aspect 10: The foamed material of any one of aspects 1 to 9, wherein the foamed material comprises: 65 to 74.9 weight percent of polystyrene; 25 to 34.9 weight percent of the poly(phenylene ether); 0.1 to 3 weight percent of the nucleating agent; and wherein weight percent is based on the total weight of the foamed material. [0084] Aspect 11: The foamed material of any one of aspects 1 to 9, wherein the foamed material comprises: 50 to 93.9 weight percent of polystyrene; 5 to 40 weight percent of the poly(phenylene ether); 1 to 10 weight percent of the organophosphate ester flame retardant; 0.1 to 3 weight percent of the nucleating agent; and wherein weight percent is based on the total weight of the foamed material. [0085] Aspect 12: The foamed material of any one of aspects 2 to 11, wherein the masterbatch comprises 20 to 55 weight percent of the first portion of polystyrene; 45 to 65 weight percent of the poly(phenylene ether); and optionally, 5 to 20 weight percent of the organophosphate ester flame retardant; wherein weight percent is based on the total weight of the masterbatch. [0086] Aspect 13: A method of making a foamed material, the method comprising: melt blending a first portion of polystyrene; the poly(phenylene ether); and optionally, the organophosphate ester flame retardant, to provide a masterbatch; melt blending in an extruder the masterbatch, a second portion of polystyrene, and the nucleating agent to form a molten thermoplastic composition; adding a blowing agent to the extruder to form a pre-foamed molten thermoplastic composition; and extruding the pre-foamed molten thermoplastic composition from the extruder to form the foamed material, wherein the foamed material comprises: 50 to 94.9 weight percent of the polystyrene; 5 to 49.9 weight percent of the poly(phenylene ether); 0.1 to 5 weight percent of the nucleating agent; and optionally, 0.5 to 20 weight percent of the organophosphate ester flame retardant; wherein weight percent is based on the total weight of the foamed material; and wherein the foamed material has a density of 20 to 100 kilograms per cubic meter, measured at 23 °C; a closed cell content of greater than 90%; and wherein a block copolymer of an alkenyl aromatic and a conjugated diene is excluded from the composition. [0087] Aspect 14: The method of aspect 13, wherein the masterbatch comprises 20 to 55 weight percent of the first portion of polystyrene; 45 to 65 weight percent of the poly(phenylene ether); and optionally, 5 to 20 weight percent of the organophosphate ester flame retardant; wherein weight percent is based on the total weight of the masterbatch. 23SHPP0032-WO-PCT (SS220061PCT) [0088] Aspect 15: An article comprising the foamed material of any one of aspects 1 to 12, preferably wherein the article is insulation, ceiling insulation, insulation for attics and crawl spaces, backing for exterior siding, interior trim, interior signs, plenums, refrigerator insulation, and freezer insulation, as well as composite laminates/ sandwich structures for aerospace/ mass transportation (applications (e.g., a train, a tram, a subway, a light rail, a monorail, an aircraft, a helicopter, a bus, a trolley, a ferry, a cable car, and the like, and wind industries, bead foams, and injection molded foams. [0089] Aspect 16: An extruded foamed material comprising: 50 to 94.9 weight percent of polystyrene; 5 to 49.9 weight percent of a poly(phenylene ether); 0.1 to 5 weight percent of a nucleating agent; and optionally, 0.5 to 20 weight percent of an organophosphate ester flame retardant; wherein weight percent is based on a total weight of the foamed material; wherein the foamed material has a density of 20 to 100 kilograms per cubic meter, measured at 23 °C; a closed cell content of greater than 90%; wherein a block copolymer of an alkenyl aromatic and a conjugated diene is excluded from the composition; and wherein the foamed material exhibits: a compression strength of greater than 0.35 N/mm², preferably greater than 0.35 to less than 1 N/mm²; or at least one of a burning rate of less than 100 millimeters per second at a thickness of 6 millimeters according to FMVSS test standard, or a HF1 rating at a thickness of 6 millimeters according to ISO9772, or a Pass rating according to EN ISO 11925-2:2010; or a combination thereof. [0090] Aspect 17: The foamed material of aspect 16, wherein the foamed material has a number average cell size of 100 to 600 micrometers. [0091] Aspect 18: The foamed material of any one of aspects 16 or 17, wherein the polystyrene comprises an atactic homopolystyrene having a melt flow index of 1.5 to 15 grams per 10 minutes, measured at 200 °C and 5 kilogram load according to ASTM D1238-13; and the poly(phenylene ether) has an intrinsic viscosity of 0.2 to 1 deciliter per gram, preferably 0.4 to 0.6 deciliters per gram, measured at 25 °C in chloroform by Ubbelohde viscometer. [0092] Aspect 19: The foamed material of any one of aspects 16-18, wherein the foamed material is made using a halogen-free blowing agent, preferably wherein the blowing agent is a non-halogenated hydrocarbon having from 1 to 9 carbon atom, carbon dioxide, ethanol, or a combination thereof. [0093] Aspect 20: The foamed material of any one of aspects 16 to 19, wherein the nucleating agent is a nanostructured nucleating agent, and the foamed material has a number average cell size of 100 to 600 micrometers. 23SHPP0032-WO-PCT (SS220061PCT) [0094] Aspect 21: The foamed material of any one of aspects 16 to 20, wherein the foamed material is made using a halogen-free blowing agent, preferably wherein the blowing agent is a non-halogenated hydrocarbon having from 1 to 9 carbon atoms, carbon dioxide, ethanol, or a combination thereof, and the composition has a compression strength of greater than 0.5 N/mm² to less than 1 N/mm². [0095] Aspect 22: The foamed material of any one of one of aspects 16 to 21, wherein the organophosphate ester flame retardant is present, and is an aromatic, halogen-free organophosphate ester flame retardant, preferably wherein the aromatic, organophosphate ester flame retardant comprises bisphenol A bis(diphenyl phosphate). [0096] Aspect 23: The foamed material of any one of aspects 16 to 22, wherein a high impact polystyrene is excluded from the composition. [0097] Aspect 24: The foamed material of aspect 16, wherein the poly(phenylene ether) has an intrinsic viscosity of 0.2 to 1 deciliter per gram, preferably 0.4 to 0.6 deciliters per gram, measured at 25 °C in chloroform by Ubbelohde viscometer; wherein the polystyrene comprises an atactic homopolystyrene having a melt flow index of 1.5 to 15 grams per 10 minutes, measured at 200 °C and 5 kilogram load according to ASTM D1238-13; wherein the organophosphate ester comprises bisphenol A bis(diphenyl phosphate); wherein the nucleating agent comprises talc; and wherein the foamed material comprises less than or equal to 1,500 parts per million by weight total of fluorine, based on the total weight of the foamed material. [0098] Aspect 25: The foamed material of any one of aspects 16 to 24, wherein the foamed material comprises less than or equal to 1,500 parts per million by weight total of chlorine, bromine, fluorine, and iodine, based on the total weight of the foamed material. [0099] Aspect 26: The foamed material of any one of aspects 1 to 24, wherein the foamed material comprises: 65 to 74.9 weight percent of polystyrene; 25 to 34.9 weight percent of the poly(phenylene ether); and 0.1 to 3 weight percent of the nucleating agent; wherein weight percent is based on the total weight of the foamed material. [0100] Aspect 27: The foamed material of any one of aspects 16 to 24, wherein the foamed material comprises: 50 to 93.9 weight percent of polystyrene; 5 to 40 weight percent of the poly(phenylene ether); 1 to 10 weight percent of the organophosphate ester flame retardant; and 0.1 to 3 weight percent of the nucleating agent; wherein weight percent is based on the total weight of the foamed material. Aspect 28: A method of making the extruded foamed material of , the many one of aspects 16-27, the method comprising: melt blending a first portion of the polystyrene; the poly(phenylene ether); and optionally, the organophosphate ester flame retardant, to provide a 23SHPP0032-WO-PCT (SS220061PCT) masterbatch; melt blending in an extruder the masterbatch, a second portion of polystyrene, and the nucleating agent to form a molten thermoplastic composition; adding a blowing agent to the extruder to form a pre-foamed molten thermoplastic composition; and extruding the pre-foamed molten thermoplastic composition from the extruder to form the foamed material. [0101] Aspect 29: The method of aspect 28, wherein the masterbatch comprises 20 to 55 weight percent of the first portion of polystyrene; 45 to 65 weight percent of the poly(phenylene ether); and optionally, 5 to 20 weight percent of the organophosphate ester flame retardant; wherein weight percent is based on the total weight of the masterbatch. [0102] Aspect 30: An article comprising the foamed material of any one of aspects 16 to 27, preferably wherein the article is insulation, ceiling insulation, insulation for attics and crawl spaces, refrigerator insulation, freezer insulation, a composite laminate, a multi-layer foam, a sandwiched foam, a foam for aerospace or rail applications, backing for exterior siding, interior trim, interior signs, or plenums, or a foam for a train, a tram, a subway, a light rail, a monorail, an aircraft, a helicopter, a bus, a trolley, a ferry, a cable car, wind industry, a bead foam, or an injection molded foam. [0103] The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of, any appropriate materials, steps, or components herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any materials (or species), steps, or components, that are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles. [0104] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. “Combinations” is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms “first,” “second,” and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms “a” and “an” and “the” do not denote a limitation of quantity, and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. “Or” means “and/or” unless clearly stated otherwise. Reference throughout the specification to “an aspect” means that a particular element described in connection with the aspect is included in at least one aspect described herein, and may or may not be present in other aspects. The term “combination thereof” as used herein includes one or more of the listed elements, and is open, allowing the presence of one or more like elements not named. In addition, it is to be understood that the described elements can be combined in any suitable manner in the various aspects. 23SHPP0032-WO-PCT (SS220061PCT) [0105] Unless specified to the contrary herein, all test standards are the most recent standard in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears. [0106] Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this application belongs. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference. [0107] Compounds are described using standard nomenclature. For example, any position not substituted by any indicated group is understood to have its valency filled by a bond as indicated, or a hydrogen atom. A dash ("-") that is not between two letters or symbols is used to indicate a point of attachment for a substituent. For example, -CHO is attached through carbon of the carbonyl group. [0108] As used herein, the term “hydrocarbyl”, whether used by itself, or as a prefix, suffix, or fragment of another term, refers to a residue that contains only carbon and hydrogen. The residue can be aliphatic or aromatic, straight-chain, cyclic, bicyclic, branched, saturated, or unsaturated. It can also contain combinations of aliphatic, aromatic, straight chain, cyclic, bicyclic, branched, saturated, and unsaturated hydrocarbon moieties. However, when the hydrocarbyl residue is described as substituted, it can, optionally, contain heteroatoms over and above the carbon and hydrogen members of the substituent residue. Thus, when specifically described as substituted, the hydrocarbyl residue can also contain one or more carbonyl groups, amino groups, hydroxyl groups, or the like, or it can contain heteroatoms within the backbone of the hydrocarbyl residue. The term "alkyl" means a branched or straight chain, saturated aliphatic hydrocarbon group, e.g., methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, t-butyl, n- pentyl, s-pentyl, and n- and s-hexyl. “Alkenyl” means a straight or branched chain, monovalent hydrocarbon group having at least one carbon-carbon double bond (e.g., ethenyl (-HC=CH2)). “Alkoxy” means an alkyl group that is linked via an oxygen (i.e., alkyl-O-), for example methoxy, ethoxy, and sec-butyloxy groups. "Alkylene" means a straight or branched chain, saturated, divalent aliphatic hydrocarbon group (e.g., methylene (-CH₂-) or, propylene (-(CH₂)₃- )). “Cycloalkylene” means a divalent cyclic alkylene group, -C_nH_2n-x, wherein x is the number of hydrogens replaced by cyclization(s). “Cycloalkenyl” means a monovalent group having one or more rings and one or more carbon-carbon double bonds in the ring, wherein all ring members are carbon (e.g., cyclopentyl and cyclohexyl). "Aryl" means an aromatic hydrocarbon 23SHPP0032-WO-PCT (SS220061PCT) group containing the specified number of carbon atoms, such as phenyl, tropone, indanyl, or naphthyl. “Arylene” means a divalent aryl group. “Alkylarylene” means an arylene group substituted with an alkyl group. “Arylalkylene” means an alkylene group substituted with an aryl group (e.g., benzyl). The prefix "halo" means a group or compound including one more of a fluoro, chloro, bromo, or iodo substituent. A combination of different halo atoms (e.g., bromo and fluoro), or only chloro atoms can be present. The prefix “hetero” means that the compound or group includes at least one ring member that is a heteroatom (e.g., 1, 2, or 3 heteroatom(s)), wherein the heteroatom(s) is each independently N, O, S, Si, or P. “Substituted” means that the compound or group is substituted with at least one (e.g., 1, 2, 3, or 4) substituents that can each independently be a C_1-9 alkoxy, a C_1-9 haloalkoxy, a nitro (-NO₂), a cyano (-CN), a C_1-6 alkyl sulfonyl (-S(=O)₂-alkyl), a C_6-12 aryl sulfonyl (-S(=O)₂-aryl), a thiol (-SH), a thiocyano (-SCN), a tosyl (CH₃C₆H₄SO₂-), a C_3-12 cycloalkyl, a C_2-12 alkenyl, a C_5-12 cycloalkenyl, a C_6-12 aryl, a C_{7- 13} arylalkylene, a C_4-12 heterocycloalkyl, and a C_3-12 heteroaryl instead of hydrogen, provided that the substituted atom’s normal valence is not exceeded. The number of carbon atoms indicated in a group is exclusive of any substituents. For example -CH₂CH₂CN is a C₂ alkyl group substituted with a nitrile. [0109] While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.

Claims

23SHPP0032-WO-PCT (SS220061PCT) CLAIMS What is claimed is: 1. An extruded foamed material comprising: 50 to 94.9 weight percent of polystyrene; 5 to 49.9 weight percent of a poly(phenylene ether); 0.1 to 5 weight percent of a nucleating agent; and optionally, 0.5 to 20 weight percent of an organophosphate ester flame retardant; wherein weight percent is based on a total weight of the foamed material; wherein the foamed material has a density of 20 to 100 kilograms per cubic meter, measured at 23 °C; a closed cell content of greater than 90%; wherein a block copolymer of an alkenyl aromatic and a conjugated diene is excluded from the composition; and wherein the foamed material exhibits: a compression strength of greater than 0.35 N/mm², preferably greater than 0.35 to less than 1 N/mm²; or at least one of a burning rate of less than 100 millimeters per second at a thickness of 6 millimeters according to FMVSS test standard, or a HF1 rating at a thickness of 6 millimeters according to ISO9772, or a Pass rating according to EN ISO 11925-2:2010; or a combination thereof. 2. The foamed material of claim 1, wherein the foamed material has a number average cell size of 100 to 600 micrometers. 3. The foamed material of any one of claims 1 or 2, wherein the polystyrene comprises an atactic homopolystyrene having a melt flow index of 1.5 to 15 grams per 10 minutes, measured at 200 °C and 5 kilogram load according to ASTM D1238- 13; and the poly(phenylene ether) has an intrinsic viscosity of 0.2 to 1 deciliter per gram, preferably 0.4 to 0.6 deciliters per gram, measured at 25 °C in chloroform by Ubbelohde viscometer. 23SHPP0032-WO-PCT (SS220061PCT) 4. The foamed material of any one of claims 1 to 3, wherein the foamed material is made using a halogen-free blowing agent, preferably wherein the blowing agent is a non-halogenated hydrocarbon having from 1 to 9 carbon atom, carbon dioxide, ethanol, or a combination thereof. 5. The foamed material of any one of claims 1 to 4, wherein the nucleating agent is a nanostructured nucleating agent, and the foamed material has a number average cell size of 100 to 600 micrometers. 6. The foamed material of any one of claims 1 to 5, wherein the foamed material is made using a halogen-free blowing agent, preferably wherein the free agent is -a non-halogenated hydrocarbon having from 1 to 9 carbon atoms, carbon dioxide, ethanol, or a combination thereof, and the composition has a compression strength of greater than 0.5 N/mm² to less than 1 N/mm². 7. The foamed material of any one of one of claims 1 to 6, wherein the organophosphate ester flame retardant is present, and is an aromatic, halogen-free organophosphate ester flame retardant, preferably wherein the aromatic, organophosphate ester flame retardant comprises bisphenol A bis(diphenyl phosphate). 8. The foamed material of any one of claims 1 to 7, wherein a high impact polystyrene is excluded from the composition. 9. The foamed material of claim 1, wherein the poly(phenylene ether) has an intrinsic viscosity of 0.2 to 1 deciliter per gram, preferably 0.4 to 0.6 deciliters per gram, measured at 25 °C in chloroform by Ubbelohde viscometer; the polystyrene comprises an atactic homopolystyrene having a melt flow index of 1.5 to 15 grams per 10 minutes, measured at 200 °C and 5 kilogram load according to ASTM D1238-13; the organophosphate ester comprises bisphenol A bis(diphenyl phosphate); the nucleating agent comprises talc; and the foamed material comprises less than or equal to 1,500 parts per million by weight total of fluorine, based on the total weight of the foamed material. 23SHPP0032-WO-PCT (SS220061PCT) 10. The foamed material of any one of claims 1 to 9, wherein the foamed material comprises less than or equal to 1,500 parts per million by weight total of chlorine, bromine, fluorine, and iodine, based on the total weight of the foamed material. 11. The foamed material of any one of claims 1 to 9, wherein the foamed material comprises: 65 to 74.9 weight percent of polystyrene; 25 to 34.9 weight percent of the poly(phenylene ether); and 0.1 to 3 weight percent of the nucleating agent; wherein weight percent is based on the total weight of the foamed material. 12. The foamed material of any one of claims 1 to 9, wherein the foamed material comprises: 50 to 93.9 weight percent of polystyrene; 5 to 40 weight percent of the poly(phenylene ether); 1 to 10 weight percent of the organophosphate ester flame retardant; and 0.1 to 3 weight percent of the nucleating agent; wherein weight percent is based on the total weight of the foamed material. 13. A method of making the extruded foamed material of any one of claims 1 to 12, the method comprising: melt blending a first portion of the polystyrene; the poly(phenylene ether); and optionally, the organophosphate ester flame retardant, to provide a masterbatch; melt blending in an extruder the masterbatch, a second portion of polystyrene, and the nucleating agent to form a molten thermoplastic composition; adding a blowing agent to the extruder to form a pre-foamed molten thermoplastic composition; and extruding the pre-foamed molten thermoplastic composition from the extruder to form the foamed material. 14. The method of claim 13, wherein the masterbatch comprises: 20 to 55 weight percent of the first portion of polystyrene; 45 to 65 weight percent of the poly(phenylene ether); and 23SHPP0032-WO-PCT (SS220061PCT) optionally, 5 to 20 weight percent of the organophosphate ester flame retardant; wherein weight percent is based on the total weight of the masterbatch. 15. An article comprising the foamed material of any one of claims 1 to 12, preferably wherein the article is insulation, ceiling insulation, insulation for attics and crawl spaces, refrigerator insulation, freezer insulation, a composite laminate, a multi-layer foam, a sandwiched foam, a foam for aerospace or rail applications, backing for exterior siding, interior trim, interior signs, or plenums, or a foam for a train, a tram, a subway, a light rail, a monorail, an aircraft, a helicopter, a bus, a trolley, a ferry, a cable car, wind industry, a bead foam, or an injection molded foam.