GB1559052A

GB1559052A - Thermoplastic polyphenylene ether resin moulding compositions

Info

Publication number: GB1559052A
Application number: GB48047/77A
Authority: GB
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1976-12-20
Filing date: 1977-11-18
Publication date: 1980-01-16
Also published as: DD133962A5; AU513181B2; FR2374378A1; CA1119742A; DE2750242A1; DE2750242C2; NL7712660A; IT1088289B; BR7708529A; JPS5394540A; MX146397A; SU865130A3; FR2374378B1; AU3170277A

Description

(54) IMPROVEMENTS IN THERMOPLASTIC POLYPHENYLENE ETHER RESIN MOULDING COMPOSITIONS (71) We, GENERAL ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of New York, United States of America, of I River Road, Schenectady 12305, State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to thermoplastic moulding compositions of a polyphenylene ether resin, a styrene resin, and a radial teleblock copolymer of a vinyl aromatic compound and a saturated rubber. The compositions of this invention provide moulded articles having good mechanical properties, including improved impact resistance. Reinforced and flame-retardant compositions are also provided.

The polyphenylene ether resins are a family of engineering thermoplastics that are well known to the polymer art. These polymers may be made by a variety of catalytic and non-catalytic processes from the corresponding phenols or reactive derivatives thereof. By way of illustration, certain of the polyphenylene ethers are disclosed in Hay, U.S. 3,306,874 and 3,306,875, and in Stamatoff, U.S. 3,257,357 and 3,257,358. In the Hay patents, the polyphenylene ethers are prepared by an oxidative coupling reaction comprising passing an oxygen-containing gas through a reaction solution of a phenol and a metalamine complex catalyst. Other disclosures relating to processes for preparing polyphenylene ether resins, including graft copolymers of polyphenylene ethers with styrene type compounds, are found in Fox, U.S. 3,356,761; Sumitomo, U.K. 1,291,609: Bussink et al., U.S. 3,337,499; Blanchard et al., U.S. 3,219,626; Laakso et al., U.S.

3,342,892; Borman, U.S. 3,344,166; Hori et al., U.S. 3,384,619; Faurote et al., U.S.

3,440,217; and disclosures relating to metal based catalysts which do not include amines, are known from patents such as Wieden et al., U.S. 3,442,885 (copperamidines); Nakashio et al., U.S. 3,573,257 (metal-alcoholate or -phenolate); Kobayashi et al., U.S. 3,455,880 (cobalt chelates); and the like. In the Stamatoff patents, the polyphenylene ethers are produced by reacting the corresponding phenolate ion with an initiator, such as peroxy acid salt, an acid peroxide, a hypohalite, in the presence of a complexing agent. Disclosures relating to non-catalytic processes, such as oxidation with lead dioxide, silver oxide, etc., are described in Price et al., U.S. 3,382,212. Cizek, U.S.

3,383,435 disclosures polyphenylene etherstyrene resin compositions.

The processing of polyphenylene ether resins on injection molding and extrusion equipment is enhanced when the polyphenylene ethers are combined with styrene resins, e.g., crystal homopolystyrene or rubber-modified high-impact polystyrenes. These polymers are combinable in a wide range of porportions, e.g., from 1 to 99 parts of polyphenylene ether and from 99 to 1 parts of styrene resin.

Compositions comprising from 10 to 60 parts of polyphenylene ether and 90 to 40 parts of styrene resin offer an especially wide range of desirable design properties.

Such combinations are disclosed in Cizek, U.S. 3,383,435. The thermoplastic compositions disclosed in Cizek can include a rubber-modified high-impact styrene resin, as well as a homopolystyrene. Highimpact styrene resins are especially useful in providing polyphenylene ether compositions which possess good resistance to impact.

It is disclosed in Laid-open German Application 2,713,509 that compositions of a polyphenylene ether resin, a styrene resin, and a radial teleblock copolymer of a vinyl aromatic compound and a conjugated diene, e.g., a styrene-butadiene radial teleblock copolymer, provide molded articles of good impact strength.

It has now been surprisingly discovered that when compositions are prepared from a polyphenylene ether resin, a styrene resin, and a hydrogenated radial teleblock copolymer of a vinyl aromatic compound and a polymer of a conjugated diene the resulting compositions provide moulded articles of improved surface gloss. The radial hydrogenated teleblock copolymers employed in the present invention have been found to be compatible with, and effective for, compositions of relatively high polyphenylene ether resin content, e.g., 50 parts by weight or more, and low molecular weight crystal polystyrene, as well as compositions of relatively low polyphenylene ether resin content, e.g., 35 parts by weight or less, and high-impact polystyrene.

As used herein, the term "hydrogenated radial teleblock copolymer" refers to branched polymers having segments, or blocks, which are comprised of a saturated polymer of a conjugated diene, blocks of a vinyl aromatic polymer, and a coupling agent. More particularly, in the copolymer structure, several chains of the rubber, usually three or more, extend from a coupling agent, with each chain terminating at its other end with a block of the vinyl aromatic polymer. It is generally believed that incompatibility of the block segments in the radial teleblock co-polymer promotes the formation of a two-phase system with blocks of the vinyl aromatic polymer coalescing to form discrete regions, or "domains". These domains simulate the effect of cross-links between the chains of elastomer, and a branched elastomeric network is thus formed comprising blocks of a saturated polymer of a conjugated diene, blocks of vinyl aromatic polymer, and a coupling agent.

Radial teleblock copolymers are known in the art. For instance, detailed descriptions of these materials are given by Marrs et al. In Adhesive Age, December, 1971, pp. 15-20 and by Haws et.al. in Rubber World, January, 1973, pp. 27-32.

Hydrogenation of radial teleblock copolymers is also known in the art.

According to the present invention, there are provided thermoplastic moulding compositions which comprise an intimate admixture of: (i) a polyphenylene ether resin; (ii) a styrene resin; and (iii) a hydrogenated radial teleblock copolymer of a vinyl aromatic compound, a polymer of a conjugated diene, and a coupling agent.

Within the invention broadly described above, the styrene resin component (ii) can be either homopolystyrene or a rubbermodified high-impact polystyrene. The radial tele-block copolymer (iii) is preferably a branched copolymer of styrene and saturated polymer of a conjugated diene, containing a relatively small, effective amount of a coupling agent selected from among epoxidizedpolybutadiene (e.g., Oxiron 2000 or Oxiron 2001), SiC 14, or mixtures thereof.

The polyphenylene ether resin (i) is preferably one of a family having repeating units represented by the formula:

wherein the oxygen ether atom of one unit is connected to the benzene nucleus of the next adjoining unit, n is positive and is at least 50, and each Q is hydrogen or a monovalent substituent selected from the group consisting of halogen, hydrocarbon radicals free of a tertiary alpha-carbon atom, halohydrocarbon and halohydrocarbonoxy radicals having at least two carbon atoms between the halogen atom and the phenyl nucleus, and hydrocarbonoxy radicals.

Examples of polyphenylene ethers corresponding to the above formula can be found in the above-referenced patents of Hay and Stamatoff.

For purposes of the present invention an especially preferred family of polyphenylene ethers includes those having alkyl substitution in the two positions ortho to the oxygen ether atom, i.e., those of the above formula wherein each Q is alkyl, most preferably having from 1 to 4 carbon atoms.

The most preferred polyphenylene ether resin is poly(2,6-dimethyl- 1 4-phenylene) ether, preferably having an intrinsic viscosity of about 0.5 deciliters per gram as measured in chloroform at 30"C.

The preferred styrene resins (ii) will be those having at least 25% by weight of repeating units derived from a vinyl aromatic monomer of the formula:

wherein R1 and R2 are selected from the group consisting of hydrogen and alkyl or alkenyl groups of from 1 to 6 carbon atoms; R3 and R4 are selected from the group consisting of chlorine, bromine, hydrogen, and alkyl groups of from 1 to 6 carbon atoms; and R5 and R6 are selected from the group consisting of hydrogen and alkyl and alkenyl groups of from 1 to 6 carbon atoms or R5 and R6 may be concatenated together with hydrocarbyl groups to form a naphthyl group. These compounds are free of any substituent that has a tertiary carbon atom.

Specific examples of vinyl aromatic monomers include styrene, chlorostyrene, a- methylstyrene, vinyl xylene, divinylbenzene, and vinyl naphthalene.

The vinyl aromatic monomer may be copolymerized with materials such as those having the general formula:

wherein the dotted lines each represent a single or a double carbon to carbon bond; R7 and R8 taken together represent a

linkage; R9 is selected from the group consisting of hydrogen, vinyl, alkyl of from 1 to 12 carbon atoms, alkenyl of from 1 to 12 carbon atoms, alkylcarboxylic of from 1 to 12 carbon atoms, and alkenylcarboxylic of from 1 to 12 carbon atoms; one of n and n' is 1, and the other is 0 or 2, depending on the position of the carbon-carbon double bond: and m is 0 or an integer of from 1 to 9.

Examples include maleic anhydride, citraconic anhydride, itaconic anhydride and aconitic anhydride.

Merely by way of illustration, the styrene resins (ii) include homopolymers such as polystyrene and monochloro-polystyrene, the modified polystyrenes, such as rubbermodified, high-impact polystyrene, and the styrene containing copolymers, such as the styrene-acrylonitrile copolymers, styrenebutadiene copolymers, styrene acrylonitrile-a-alkyl styrene copolymers, styrene-acrylonitrile-butadiene copolymers, poly - a - methyl-styrene, copolymers of ethylvinylbenzene, and divinylbenzene, styrene-maleic anhydride copolymers, styrene-butadiene-styrene block copolymers and styrene-butadiene block copolymers, and styrene-butadiene-styrene maleic anhydride block copolymers.

The styrene-maleic anhydride copolymers are described in U.S. 3,971,939, U.S. 3,336,267, and U.S. 2,769,804, Especially preferred styrene resins are homopolystyrene and rubber-modified high-impact polystyrene resins, i.e., those which have been modified by natural or synthetic polymeric materials which are elastomers at room temperature, e.g., 20 to 25"C., such as polystyrene resins containing polybutadiene or rubbery styrenebutadiene copolymers.

A preferred high-impact polystyrene is FG 834, available from Foster-Grant Co., which is a rubber-modified high-impact polystyrene containing about 8 " polybutadiene rubber. A preferred low molecular weight homopolystyrene is KPTL-5, commercially available from Arco Polymers, Inc., Pittsburgh, Pa., having a number average molecular weight of about 40,000. A preferred homopolystyrene of relatively high molecular weight is DYL-8G, with a number average molecular weight of about 150,000, also available from Arco.

Radial teleblock copolymers are available commercially or can be prepared by following the teachings of the prior art. As an illustration, they can be made by polymerizing conjugated dienes, e.g., butadiene, and vinyl aromatic compounds, e.g., styrene in the presence of an organometallic initiator, e.g., nbutyllithium, to produce copolymers which contain an active metal atom, such as lithium, on one end of each of the polymer chains. These metal atom-terminated polymers are then reacted with a coupling agent which has at least three active sites capable of reacting with the carbon-metal atom bonds on the polymer chains and replacing the metal atoms on the chains.

This results in polymers which have relatively long branches which radiate from a nucleus formed by the poly-functional coupling agent. Such a method of preparation is described in detail in Zelinski et al., U.S. 3,281,383.

The coupling agents for radial teleblock copolymers can be chosen from among polyepoxides, polyisocyanates, polyimines, polyaldehydes, polyketones, polyanhydrides, polyesters, and polyhalides.

These materials can contain two or more types of functional groups, such as the combination of epoxy and aldehyde groups or isocyanate and halide groups. The coupling agents are described in detail in the above-mentioned U.S. 3,281,383.

The conjugated dienes of radial teleblock copolymers include compounds such as 1,3butadiene, isoprene, 2,3-dimethyl-1,3butadiene, 1,3-pentadiene, and 3-butyl-1,3octadiene.

The vinyl aromatic polymers may be prepared from vinyl aromatic compounds of Formula II. They include styrene, 1vinylnaphthalene, 2-vinylnaphthalene, and the alkyl, cycloalkyl, aryl, alkaryl, and aralkyl derivatives thereof. Examples include 3-methylstyrene, 4-n-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2 ethyl-4-benzylstyrene, 4-p-tolystyrene, and 4-(4-phenyl-n-butyl) styrene.

Hydrogenation of radial teleblock copolymers to form the hydrogenated radial teleblock copolymers (iii) can be carried out by any of several known procedures. See by way of illustration, De Vault, U.S. 3,696,088.

In preferred compositions, the hydrogenated radial teleblock copolymer will be a radial teleblock copolymer of styrene and a saturated rubber, with terminal blocks derived from styrene, and a coupling agent selected from epoxidized polybutadiene, SiC14, or mixtures thereof.

Especially preferred epoxidized polybutadiene coupling agents are available commercially under the trade names Oxiron 2000 and Oxiron 2001.

The molecular weight of the hydrogenated radial teleblock copolymer and the ratios of the co-monomers thereof can vary broadly. In preferred embodiments the molecular weight of the hydrogenated radial teleblock copolymer will be from 75,000 to 350,000, and will comprise from 1 to 45 parts by weight of the vinyl aromatic compound and from 99 to 55 parts by weight of the saturated rubber, based on the weight of the radial teleblock copolymer. The amount of coupling agent in the copolymer will depend on the particular agent and the amount of organometallic initiator used.

Generally, relatively small amounts of coupling agent, e.g., from 0.1 to I part by weight per 100 parts of resin are employed.

Preferred hydrogenated radial teleblock copolymers include Solprene 502 and 512 (containing 70 parts by weight of hydrogenated butadiene units and 30 parts by weight of styrene units), which are available commercially from Philips Petroleurn Co., Stowe, Ohio ("Solprene' is a Registered Trade Mark). These materials also include a relatively minor amount of a coupling agent, e.g., less than 1 part by weight of a coupling agent per 100 parts by weight of copolymer.

Components (i), (ii), and (iii) are combinable in a fairly wide range of proportions. Preferably, the compositions of this invention will comprise from 10 to 65 parts by weight of polyphenylene ether resin (i), from 90 to 35 parts by weight of styrene resin (ii), and from 1 to 25 parts by weight of hydrogenated radial teleblock copolymer (iii), based on the total weight of the composition.

The compositions of the invention can also include other ingredients, such as flame-retardants, extenders, processing aids, pigments, stabilizers, for their conventionally employed purposes.

Reinforcing fillers, in amounts sufficient to impart reinforcement, can be used, such as aluminum, iron or nickel, and non-metals, such as carbon filaments, silicates, such as acicular calcium silicate, asbestos, titanium dioxide, potassium titanate and titanate whiskers and glass flakes and fibers. It is to be understood that, unless the filler adds to the strength and stiffness of the composition, it is only a filler and not a reinforcing filler as contemplated herein. In particular, the reinforcing fillers increase the flexural strength, the flexural modulus, the tensile strength and the heat distortion temperature.

In particular, the preferred reinforcing fillers are of glass, most preferably, fibrous glass filaments comprised of lime-aluminum borosilicate glass that is relatively soda free.

This is known as "E" glass.

In general, the best properties will be obtained if the sized filamentous glass reinforcement comprises from about I to about 80% by weight based on the combined weight of glass and polymers and preferably from 10 to 50%, most preferably, 10 to 40% by weight.

In accordance with the invention flameretardant compositions are provided which contain a flame-retarding additive selected from a halogenated organic compound, a halogenated organic compound in admixture with an antimony compound, elemental phosphorous, or a phosphorus compound or compounds containing phosphorus-nitrogen bonds, or a mixture of two or more of the foregoing.

In general, however, the amount of the flame-retarding additive will be from 0.5 to 50 parts by weight per hundred parts of components (i), (ii), and (iii).

The compositions of the invention may be formed by conventional techniques, that is, by first dry mixing the components to form a premix, and then passing the premix through an extruder at an elevated temperature, e.g. 425 to 6400 F.

By way of illustration, glass roving (a bundle of strands of filaments) is chopped into small pieces, e.g. 1/8" to 1" in length, and preferably less than +" in length and put into an extrusion compounder with (i) the polyphenylene ether resin, (ii) the styrene resin, (iii) the hydrogenated radial teleblock copolymer, and (iv) the flame-retardant additive(s), to produce molding pellets. The fibers are shortened and predispersed in the process, coming out at less than 1/16" long.

In another procedure, glass filaments are ground or milled to short lengths, are mixed with the polyphenylene ether resin, the styrene resin, the radial teleblock copolymer, and optionally, flame-retardant additive, by dry blending, and then are either fluxed on a mill and ground, or are extruded and chopped.

In addition, compounding should be carried out to insure that the residence time in the machine is short; that the temperature is carefully controlled; that the frictional heat is utilized; and that an intimate mixture between the resins and the additives is obtained.

The following examples are set forth as further illustration of the invention and are not to be construed as limiting the invention thereto.

Comparative Example (Sample A) A premix comprised of 55 parts by weight of poly-(2,6-dimethyl- I ,4-phenylene) ether resin (PPO), and 45 parts by weight of Foster-Grant's Fosterflux 834 (FG 834), a rubber-modified polystyrene containing about 8% polybutadiene rubber was prepared by dry mixing these components with 4 parts tri-phenyl phosphate, 1.5 parts polyethylene, 1 part tridecyl-phosphite, 0.15 parts zinc sulfide, and 0.15 parts zinc oxide.

The premix was then compounded on a 28 mm twin-screw extruder at about 500"F.

The extrudate was cooled and chopped into pellets, and the pellets were moulded into test bars on a Newbury injection molding machine.

Example I. (Sample B) Comparative Example I was repeated with the exception that the 45 parts of FG 834 were replaced by 30 parts of Sinclair Kopper Co.'s Dylene 8G (DYL-8G), "crystal" polystyrene, and Phillips Petroleum's Solprene 502CX (SOL-502), which is a radial teleblock copolymer containing hydrogenated rubber blocks.

Example II.

The composition prepared in the Comparative Example and Example I were tested, and the results were as follows: Composition T.Y. T.E. Izod GIMP HDT GLOSS MV Sample A 8900 83 3.0 210 245 53 2100 Sample B 7900 20 6.0 225 259 65 2150 T.Y.-Tensile Yield Strength (psi) T.E.-Tensile Elongation (%) Izod-Notched Izod Impact Strength (ft lbs./in. notch) GIMP-Gardner Impact (in. Ibs.) HDT-Heat Deflection Temperature ("F) GLOSS-45" Surface Gloss (dimensionless) MV-Melt Viscosity z 5400 F, 1500 sec-' (poise) As can be seen above, a thermoplastic composition in accordance with the invention, Sample B, demonstrated improved impact resistance and unexpected improvements in surface gloss over a typical commercial composition, Sample A.

Comparative Example II. (Sample C) A premix comprised of 50 parts by weight of PPO and 50 parts by weight FG 834 was prepared by dry mixing these components with 3 parts triphenyl phosphate, 1.5 parts polyethylene, 1 part tridecylphosphite, 0.15 parts zinc sulfide, 0.15 parts zinc oxide, and 3 parts titanium dioxide. The premix was then compounded on a 28 mm twin-screw extruder at about 5000 F. The extrudate was cooled and chopped into pellets, and the pellets were moulded into test bars on a Newbury injection molding machine.

Comparative Example (Sample D) Comparative Example II was repeated with the exception that the 50 parts of FG 834 were replaced by 42 parts of DYL-8G and 8 parts of Phillips Petroleum's Solprene 411 (SOL-411), a radial teleblock copolymer comprising styrene and butadiene.

Example III. (Sample E) The procedure of Comparative Example II was repeated with the exception that the 50 parts of FG 834 were replaced by 38 parts of DYL-8G and 12 parts of SOL-502.

Example IV The compositions prepared in Comparative Examples II and III and Example II were tested to determine the effect of aging, and the results were as follows: Days&commat; Izod T.E.

115"C C D E C D E 6 4.5 4.0 4.3 94 89 25 1I 3.0 3.3 2.5 30 20 16 28 2.2 2.1 2.4 16 7 13 50 1.0 1.1 1.9 6 6 10 63 1.8 9 91 1.3 8 The results unquestionably show the improved retention of ductility during heat aging of Sample E, a composition in accordance with the invention, over Samples C and D, two known compositions.

WHAT WE CLAIM IS: 1. A thermoplastic molding composition which comprises an intimate admixture of: (i) a polyphenylene ether resin; (ii) a styrene resin; and (iii) a hydrogenated radial teleblock

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

in the machine is short; that the temperature is carefully controlled; that the frictional heat is utilized; and that an intimate mixture between the resins and the additives is obtained.

The following examples are set forth as further illustration of the invention and are not to be construed as limiting the invention thereto.

Comparative Example (Sample A) A premix comprised of 55 parts by weight of poly-(2,6-dimethyl- I ,4-phenylene) ether resin (PPO), and 45 parts by weight of Foster-Grant's Fosterflux 834 (FG 834), a rubber-modified polystyrene containing about 8% polybutadiene rubber was prepared by dry mixing these components with 4 parts tri-phenyl phosphate, 1.5 parts polyethylene, 1 part tridecyl-phosphite, 0.15 parts zinc sulfide, and 0.15 parts zinc oxide.

The premix was then compounded on a 28 mm twin-screw extruder at about 500"F.

The extrudate was cooled and chopped into pellets, and the pellets were moulded into test bars on a Newbury injection molding machine.

Example I. (Sample B) Comparative Example I was repeated with the exception that the 45 parts of FG 834 were replaced by 30 parts of Sinclair Kopper Co.'s Dylene 8G (DYL-8G), "crystal" polystyrene, and Phillips Petroleum's Solprene 502CX (SOL-502), which is a radial teleblock copolymer containing hydrogenated rubber blocks.

Example II.

The composition prepared in the Comparative Example and Example I were tested, and the results were as follows: Composition T.Y. T.E. Izod GIMP HDT GLOSS MV Sample A 8900 83 3.0 210 245 53 2100 Sample B 7900 20 6.0 225 259 65 2150 T.Y.-Tensile Yield Strength (psi) T.E.-Tensile Elongation (%) Izod-Notched Izod Impact Strength (ft lbs./in. notch) GIMP-Gardner Impact (in. Ibs.) HDT-Heat Deflection Temperature ("F) GLOSS-45" Surface Gloss (dimensionless) MV-Melt Viscosity z 5400 F, 1500 sec-' (poise) As can be seen above, a thermoplastic composition in accordance with the invention, Sample B, demonstrated improved impact resistance and unexpected improvements in surface gloss over a typical commercial composition, Sample A.

Comparative Example II. (Sample C) A premix comprised of 50 parts by weight of PPO and 50 parts by weight FG 834 was prepared by dry mixing these components with 3 parts triphenyl phosphate, 1.5 parts polyethylene, 1 part tridecylphosphite, 0.15 parts zinc sulfide, 0.15 parts zinc oxide, and 3 parts titanium dioxide. The premix was then compounded on a 28 mm twin-screw extruder at about 5000 F. The extrudate was cooled and chopped into pellets, and the pellets were moulded into test bars on a Newbury injection molding machine.

Comparative Example (Sample D) Comparative Example II was repeated with the exception that the 50 parts of FG 834 were replaced by 42 parts of DYL-8G and 8 parts of Phillips Petroleum's Solprene 411 (SOL-411), a radial teleblock copolymer comprising styrene and butadiene.

Example III. (Sample E) The procedure of Comparative Example II was repeated with the exception that the 50 parts of FG 834 were replaced by 38 parts of DYL-8G and 12 parts of SOL-502.

Example IV The compositions prepared in Comparative Examples II and III and Example II were tested to determine the effect of aging, and the results were as follows: Days&commat; Izod T.E.

115"C C D E C D E

6 4.5 4.0 4.3 94 89 25 1I 3.0 3.3 2.5 30 20 16

28 2.2 2.1 2.4 16 7 13

50 1.0 1.1 1.9 6 6 10

63 1.8 9

91 1.3 8 The results unquestionably show the improved retention of ductility during heat aging of Sample E, a composition in accordance with the invention, over Samples C and D, two known compositions.

WHAT WE CLAIM IS: 1. A thermoplastic molding composition which comprises an intimate admixture of: (i) a polyphenylene ether resin; (ii) a styrene resin; and (iii) a hydrogenated radial teleblock

copolymer comprising a vinyl aromatic polymer, a polymer of a conjugated diene, and a coupling agent.
2. A composition as claimed in claim 1 wherein the polyphenylene ether resin has repeating units of the structural formula:

wherein the oxygen ether atom of one unit is connected to the benzene nucleus of the next adjoining unit, n is positive and is at least 50, and each Q is hydrogen or a monovalent substituent selected from halogen, hydrocarbonoxy radicals, hydrocarbon radicals free of a tertiary alpha-carbon atom, halo-hydrocarbon or halohydrocarbonoxy radicals having at least two carbon atoms between the halogen atom and the phenol nucleus; and wherein, in said styrene resin at least 25% by weight of repeating units are derived from a vinyl aromatic monomer of the formula:

wherein R' and R2 are selected from hydrogen and alkyl or alkenyl groups of from 1 to 6 carbon atoms; R3 and R4are selected from chlorine, bromine, hydrogen, and alkyl groups of from 1 to 6 carbon atoms; and R5 and R6 are selected from hydrogen and alkyl and alkenyl groups of from 1 to 6 carbon atoms; R3 and R4 are be concatenated together with hydrocarbyl groups to form a naphthyl group, these compounds being free of any substituent having a tertiary carbon atom.
3. A composition as claimed in claim 1 or claim 2 wherein said polyphenylene ether resin is poly (2,6-di-methylphenylene 1,4)ether.
4. A composition as claimed in any one of the preceding claims wherein said styrene resin is a low molecular weight homopolystyrene.
5. A composition as claimed in any one of claims 1 to 3 wherein said styrene resin is a rubber-modified high-impact polystyrene.
6. A composition as claimed in any one of the preceding claims wherein said radial teleblock copolymer contains 1 to 45 parts by weight of the vinyl aromatic polymer and correspondingly 99 to 55 parts by weight of the saturated rubber.
7. A composition as claimed in any one of the preceding claims wherein said coupling agent is a polymer selected from polyepoxides, polyisocyanates, polyimines, polyaldehydes, polyketones, polyanhydrides, polyesters, and polyhalides.
8. A composition as claimed in any one of the preceding claims wherein in said radial teleblock copolymer the vinyl aromatic polymer is polystyrene, the polymer of a conjugated diene is polybutadiene, and the coupling agent is selected from epoxidized polybutadiene, SiC 14, and mixtures thereof.
9. A composition as claimed in any one of the preceding claims comprising 10 to 65 by weight percent of said poly-phenylene ether resin, 90 to 35 weight percent of said styrene resin, and I to 25 by weight percent of said radial teleblock copolymer, based on the total weight of the composition.
10. A composition as claimed in any one of the preceding claims which further comprises a reinforcing filler.
11. A composition as claimed in any one of the preceding claims which further comprises a flame-retardant additive.
12. A thermoplastic moulding composition as claimed in claim 1 substantially as hereinbefore described in any one of Examples I to IV.