MXPA99011770A - Vinyl aromatic polymer coupling and foams - Google Patents

Abstract

The invention includes a process comprising steps of (1) forming an admixture of (a) a vinyl aromatic polymer and (b) a coupling amount of at least one poly(sulfonyl azide);(2) introducing the vinyl aromatic polymer or admixture into a melt processing device;(3) melting the vinyl aromatic polymer or admixture, and thereafter (4) exposing the admixture to a temperature, hereinafter, melt process temperature, sufficient to result in coupling of the vinyl aromatic polymer. The invention also includes a process of increasing the molecular weight of a vinyl aromatic polymer by heating an admixture of at least one vinyl aromatic polymer and a coupling amount of at least one poly(sulfonyl azide). Alternatively the invention is a process comprising steps of (1) forming, under a first pressure, a mixture of a vinyl aromatic polymer, a blowing agent and at least one poly(sulfonyl azide), with the mixture at a temperature at which the viscosity of the mixture is sufficient to retain the blowing agent when the mixture is allowed to expand;(2) extruding the mixture into a holding zone maintained at a temperature and second pressure which does not allow the mixture to foam, the holding zone having an outlet die defining an orifice opening into a zone of a third pressure lower than the first or second pressures at which the mixture foams, and an openable gate closing the die orifice;(3) periodically opening the gate;(4) substantially concurrently applying mechanical pressure by a movable ram on the mixture to eject the mixture from the holding zone through the die orifice into the zone of third pressure, at a rate greater than that at which substantial foaming in the die orifice occurs and less than that at which substantial irregularities in cross-sectional area or shape occurs;and (5) permitting the ejected mixture to expand unrestrained in at least one dimension to produce an elongated thermoplastic cellular body. The invention also includes any composition comprising a product formed by a process of the invention, said composition preferably comprising a foam or polymer and any article formed from such a composition.

Description

COUPLING AND AROMATIC VINYL POLYMER FOAMS DESCRIPTION OF THE INVENTION This invention relates to aromatic monovinylidene polymer resins, more particularly, to the coupling of said resins. In general, the basic physical properties that are usually desired in the production of molded thermoplastic resin articles are a readily processable starting resin that produces articles that are relatively strong and heat resistant. It is within the skill of the art to produce relatively strong heat-resistant articles from aromatic monovinylidene polymer resins. Most resins used to produce articles that possess these properties must be modified in some way to improve their melt flow characteristics enough to allow them to be easy as quickly processed in an available processing equipment, such as a processing equipment. injection molding, under normal conditions. To avoid the extended residence time requirements and the consequent equipment requirements, it may be desirable to polymerize the aromatic vinyl monomers to a lower molecular weight and subsequently develop the polymers of low molecular weight to higher molecular weight polymers. It may also be desirable to use lower molecular weight aromatic vinyl polymers for processability and subsequently to develop the molecular weight to improve the melt strength and extension properties of a foam material. The increase in molecular weight could preferably also increase the cell size or density, or both. Most preferably, with the treatment of the polymer starting materials, a further production polymer can be obtained. high in a foam (eg, in kilograms per hour) or a lower density than with the untreated starting material in the same foaming process, while retaining a resistance to cracking or flexibility, or both, equivalent or better. In the past, difunctional sulfonyl azides have been used to bridge such polymers as polypropylene, for example, as described by Cox et al., In the U.S. patent. 3,336,268, but such reactions lead to entanglement. In this way, the reactions can be expected to have adverse effects on foams or other properties of aromatic vinyl polymers. The patent of E.U.A. No. 4,694,025 discloses a process for preparing interlaced aromatic vinyl polymer foam compositions using azidosilanes (sulfonyl azides). However, these systems are interlocked, which can have adverse effects on foams or other properties of aromatic vinyl polymers.

It has now been found that the molecular weight of an aromatic vinyl polymer can be developed using reactions with poly (sulfonyl) azide. The reaction is also useful in treating foam polymer supply material to retain or improve processability and to subsequently develop the molecular weight to improve the melt strength and spreading properties of a foam material. Advantageously, the cell size preferably also increased. Most preferably, by treating the polymer starting materials through the process of the invention, at least one polymer of higher production to a foam (eg, in kilograms per hour) or lower density than with the material can be obtained. unit not treated in the same foaming process while retaining a resistance to cracking or flexibility, or both, equivalent or better. The invention includes a process comprising the steps of (1) forming a mixture of (a) an aromatic vinyl polymer and (b) a coupling amount of at least one poly (sulfonyl) azide; (2) introducing the aromatic vinyl polymer or mixture into a fusion processing device, (3) melting the aromatic vinyl polymer or mixture, and then (4) exposing the mixture to a temperature, hereinafter, the melting process temperature, sufficient to result in the coupling of the aromatic vinyl polymer. With the exception of step (4), the steps are optionally performed in any sequence including overlap, but preferably in numerical order. Preferably, the coupling amount is from 0.005 pph to 2 pph based on the amount of the aromatic vinyl polymer; the aromatic vinyl polymer is a styrene polymer; or the melting process temperature is greater than 150 ° C and below 250 ° C; the fusion processing device; a uniform mixture of poly (sulfonyl azide) and aromatic vinyl polymer is formed before the mixture is exposed to temperatures sufficient to result in coupling; or a combination thereof. The poly (sulfonyl) azide preferably has a structure, X-R-X, wherein each X is S02N3 and R represents an unsubstituted or inertly substituted hydrocarbyl, hydrocarbyl ether or a silicon-containing group; the poly (sulfonyl) azide has sufficient carbon, oxygen or silicon atoms to separate the sulfonyl azide groups sufficiently to allow an easy reaction between the aromatic vinyl polymer and the sulfonyl azide; R includes at least one aryl group between the sulfonyl groups; or a combination thereof. The invention also includes a process for increasing the molecular weight of an aromatic vinyl polymer by heating a mixture of at least one aromatic vinyl polymer and a coupling amount of at least one poly (sulfonyl) azide. In a preferred embodiment, foams are formed. Then, preferably, the mixture that goes in step (4) further comprises a blowing agent and the process further comprises a step of extruding the resulting mixture into a zone having a pressure lower than the pressure in step (4), cooling the mixture and forming a resulting foam. Preferably, the foam has a density of less than 65 kg / m3 or a cell size of less than 4 millimeters and greater than 0.05 millimeters in diameter or a combination thereof. Alternatively, the invention is a process comprising the steps of (1) forming, under a first pressure, a mixture of an aromatic vinyl polymer, a blowing agent and at least one poly (sulfonyl) azide, with the mixing at a temperature at which the viscosity of the mixture is sufficient to retain the blowing agent when the mixture is allowed to expand; (2) extrude the mixture to a support zone maintained at a temperature and second pressure, which does not allow that the mixture forms froth, the support zone having an exit die defining an orifice opening in an area of a third lower pressure than the first and second pressures to which the mixture foams, and a gate that can be open by closing the hole of the die; (3) periodically opening the gate; (4) substantially and concurrently applying mechanical pressure through a moving ram on the mixture to eject the mixture from the support zone through the die hole towards the third pressure zone, at a speed greater than that at which substantial foaming occurs in the die orifice and less than that at which substantial irregularities occur in the cross-sectional area or configuration; and (5) allowing the ejected mixture to expand without restricting in at least one direction to produce an elongate thermoplastic cell body. • The invention also includes any composition comprising a product formed through a process of the invention, said composition preferably comprising a foam or polymer and any article formed from said composition. The article is preferably in the form of sound or temperature insulation, development or construction foam, manufacturing foam, craft foam, flotation foam or packaging. This invention involves the coupling of polymers of aromatic vinyl monomers. Aromatic vinyl monomers suitable for the preparation of such polymers for use in the present invention include, but are not limited to, those aromatic vinyl monomers known to be used in polymerization processes, such as those described in the U.S. Patents. 4,666,987; 4,572,819 and 4,585,825. Preferably, the monomer is of the formula: R '"I Ar-C = CH2 wherein R 'is hydrogen or methyl, Ar is an aromatic ring structure having from 1 to 3 aromatic rings with or without alkyl, halogen or haloalkyl substitution, wherein any alkyl group contains 1 to 6 carbon atoms and haloalkyl refers to an alkyl group substituted with halogen. Preferably, Ar is phenyl or alkylphenyl, wherein alkylphenyl refers to a phenyl group substituted with alkyl, with phenyl being very preferred. Typical aromatic vinyl moiomers, which may be used, include: styrene, alpha-methylstyrene, all isomers of vinyltoluene, especially para-vinyltoluene, all isomers of ethylstyrene, propylstyrene, vinylbiphenyl, vinylnaphthalene, vinifanthracene and mixtures thereof . The aromatic vinyl monomers can also be combined with other copolymerizable monomers. Examples of such monomers include, but are not limited to, acrylic monomers such as acrylonitrile, methacrylonitrile, methacrylic acid, methyl methacrylate, acrylic acid and methyl acrylate; maleimide, phenylmaleimide and maleic anhydride. In addition, the polymerization can be conducted in the presence of a pre-dissolved elastomer to prepare products containing grafted rubber or modified by impact, examples of which are described in the U.S. Patents. Nos. 3,123,655; 3,346,520; 3,639,522 and 4,409,369. In the polymerization of high or intermediate molecular weight polymers, the method for initiation is not critical. For example, the polymerizations are conveniently initiated radical or ammonically free. The conditions suitable for the initiation of thermal free radical, as well as free radical and free radical compositions anionic initiator are within the experience of the technique. Representative free radical initiators include peroxide initiators such as peresters, for example, tertiary butyl peroxybenzoate and tertiary butyl peroxyacetate, dibenzoyl peroxide, dilauroyl peroxide, 1,1-bis-butyl tertiary-peroxocyclohexane, 1, Tertiary butyl-tert-butyl-3,3,5-trimethylcyclohexane and dicumyl peroxide. Representative ammonium initiators include well-known organo lithium initiators, such as n-butyl lithium. - Polymerization processes and process conditions for the polymerization of aromatic vinyl monomers are well known in the art. Although any polymerization process can be used, typical processes are bulk or solution polymerizations, you continue, as described in US 2,727,884 and US 3,639,372. The polymerization is typically conducted at temperatures of 80 to 200 ° C, preferably 90 to 190 ° C, most preferably 100 to 185 ° C, and most preferably 110 to 180 ° C. The present invention is also applicable to the matrix-phase or continuous, rigid polymer of rubber-modified aromatic moriovinylidene polymer compositions. The term "polymer" is used herein to refer to polymers of at least one aromatic vinyl monomer, also referred to herein as aromatic vinyl polymers, or aromatic monovinylidene polymer compositions.

- The aromatic monovinylidene polymers are those comprising at least a larger portion of a polymerized addition monomer of the formula: Ar I C = CH2 I Ri wherein R ^ is selected from the group of radicals consisting of hydrogen and alkyl radicals containing three carbons or less and Ar is selected from the group of radicals consisting of phenyl, halophenyl, alkylphenyl and alkylhalophenyl. Preferably, R-i is a hydrogen or methyl radical. Preferably, Ar is phenyl or alkylphenyl. Preferably, the polymer is polystyrene. The compositions of the invention and the articles including foams of the invention comprise a polymer material. The polymer material comprises totally or in part, a linear, aromatic monovinyl polymer coupled in accordance with the practice of the invention. The aromatic monovinyl polymer is optionally a rTomopolymer or a copolymer formed from aromatic monovinyl monomers and ethylenically unsaturated and copolymerizable comonomers Minor amounts of monoethylenically unsaturated comonomers such as C2-6 alkyl acids and esters, ionomeric derivatives and C4 dienes. -6 are optionally copolymerized with aromatic monovinyl monomers. of copolymerizable compounds include acrylic acid, methacrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic anhydride, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, vinyl acetate and butadiene. The comonomer content is less than 50% and preferably less than 30% based on the weight of the aromatic alkenyl polymer. Without considering the composition, the polymer material comprises more than 50 and preferably more than 70% by weight monomeric monovinyl aromatic units. Most preferably, the aromatic monovinyl polymer material is substantially or completely composed of monovinyl aromatic monomer units. Polystyrene is the most common family of aromatic monovinylidene polymers and, therefore, is a preferred embodiment within polystyrenes. The widely recognized categories of polymers include, but are not limited to, (1) general purpose polystyrene (GPGS), which is a styrene homopolymer which optionally contains additives such as plasticizers and / or mold release agents (e.g. , zinc stearate) and (2) high impact polystyrene (HIPS), which contains a rubber as well as optional additives such as a plasticizer or a mold release agent. The rubbers are very advantageously diene rubbers, preferably polybutadiene rubbers or polybutadiene block polystyrene and preferably present in amounts of 2 to 12% by weight.

As used herein, the Mw of a polymer means the weight average molecular weight of the polymer, while Mn means the number average molecular weight. In addition, in the compositions herein, the increased high molecular weight polymer is reflected in the Mz value of the resin, the "z average" molecular weight. The Mz of a resin is believed to more accurately show the effect of constituents of a high molecular weight resin. For the purpose of defining the present invention, molecular weight data for components having weight average molecular weights of 70,000 Spend are determined through Gel Penetration Chromatography (GPC). The GPC analysis is conveniently with a GPC column, which is linear of Mw from 600 to 2,000,000. In the case of polymers of very high average molecular weight (above 700,000 and higher), the molecular weight is exactly determined from the solution viscosity of a 10% solution of the polymer in toluene. - "The ratio of the average molecular weights in weight and number average, Mw / Mn, usually called the dispersion index, is an indication of the amplitude or narrowness of the molecular weight distribution, the larger the given number Because of this relationship, the molecular weight distribution is broader.The molecular weight distribution can also be shown graphically plotting the molecular weight record of the polymer fractions on the X axis, against the percentage of the molecular weight. total weight of the composition such that the polymer of molecular weight of shape, on the Y axis. The determination of this data using GPC is within the skill in the art and said graphs are referred to as GPC curves. In general, the GPC curves for isothermal styrenic polymers are individual bell-shaped curves, the relatively wider or narrower shape of the "bell" indicating a broad or narrow distribution as used herein, generally refers to the shape of the curves obtained by the GPC analysis of said polymers, which is reflected in the Mw / Mn ratios. Preferably, the molecular weight distribution is less than 20, preferably less than 10, and most preferably less than 5. The molecular weight distribution is preferably less than 2, and most preferably greater than 2. Preferred polymers for use as Starting materials in the practice of the invention include polymers having a molecular weight Mw of at least 50, 000 to most preferably at least 80,000, preferably at least 100,000, but preferably at least 400,000, preferably at least 350,000, and most preferably at least 300,000. Conveniently, the aromatic vinyl polymer has a melt index as determined by the method of ASTM 1238, at 200 ° C using a weight of 5 kg of less than 200 g / 10 minutes, most preferably less than 60 g / 10 minutes. For coupling purposes, the polymer is made react with a poly (sulfonyl) azide compound capable of insertion reactions to C-H bonds. Poly (sulfonyl) azide compounds having at least two azide groups capable of C-H insertion under reaction conditions are referred to herein as coupling agents. The poly (sulfonyl) azide is any compound having at least two sulfonyl azide groups (-S02N3) reactive with the polymer. Preferably, the poly (sulfonyl) azides have an XRX structure, wherein each X is S02N3 and R represents an unsubstituted or inertly substituted hydrocarbyl, hydrocarbyl ether or a silicon-containing group, preferably having sufficient carbon, oxygen or silicon, of preferably carbon atoms for separating the sulfonyl azide groups sufficiently to allow an easy reaction between the polymer and the sulfonyl azide, most preferably at least 1, preferably at least 2, most preferably at least 3 carbon atoms, oxygen or silicon, preferably carbon atoms between functional groups. Although limiting the length of R is not critical, each R advantageously has at least one carbon or silicon atom between X and preferably less than 50, preferably less than 30, and most preferably less than 20 carbon atoms, oxygen or silicon. Within these limits, the greater is better for reasons that include thermal and shock stability. When R is a straight chain alkyl hydrocarbon, preferably less than 4 carbon atoms exist among the sulfonyl azide groups to reduce the propensity of nitrene to flex and react with itself. Silicon-containing groups include silanes and siloxanes, preferably siloxanes. The term "inertly substituted" refers to the substitution with atoms or groups that do not undesirably interfere with the desired reaction (s) desired properties of the resulting coupled polymers. Such groups include fluorine, aliphatic or aromatic ether, siloxane, as well as azide groups when two or more polymer chains are to be joined. Suitable structures include R as aryl, alkyl, arylalkyl, arylalkysilane, siloxane or heterocyclic groups and other groups which are inert and separate the sulfonyl azide groups as described. Most preferably, R includes at least one aryl group between the sulfonyl groups, most preferably at least two aryl groups (such as when R is 4,4'-diphenylether or 4,4'-biphenyl). When R is an aryl group, it is preferred that the group has more than one ring, as in the case of naphthylene bis (sulfonyl) azides. The poly (sulfonyl) azides include compounds such as 1,5-pentane bis (sulfonyl) azide, 1,8-octane bis (sulfonyl) azide, 1,10-decane bis (sulfonyl) azide, bis (sulfonyl) azide of 1,1-O-octadecane, tris (sulfonyl) azide of 1-octyl-2,4,6-benzene, 4,4'-diphenyl bis (sulfonyl) azide, 1,6 bis (4'-sulfoazidophenyl) hexane, bis (sulfonyl) azide of 2,7-naphthalene and mixed sulfonyl azides of chlorinated aliphatic hydrocarbons containing an average of 1 to 8 chlorine atoms and 2 to 5 azide groups of sulfonyl molecule, and mixtures thereof. Preferred poly (sulfonyl) azides include oxy-bis- (4-sjjlfonylazidobenzene), 2,7-naphthalene-bis (sulfonylazido), 4,4'-bis (sulfonylazido) biphenyl, bis (sulfonyl) azide of ether 4 , 4'-diphenyl and bis (4-sulfonylazidophenyl) methane and mixtures thereof. The sulfonyl azides are conveniently prepared through the reaction of sodium azide with the corresponding sulfonyl chloride, although the oxidation of sulfonyl hydrazines with various reagents (nitrous acid, dinitrogen tetraoxide, nitroside tetrafluoroborate) has been used.; For coupling, poly (sulfonyl) azide is used in a coupling amount, ie an amount effective to increase the molecular weight of the polymer, preferably at least 2% compared to the starting material polymer, but less than an amount of entanglement, which is an amount sufficient to result in at least 400% increase in molecular weight. The amount is preferably less than 2 parts per 100 by weight (pph), preferably less than 1 pph, most preferably less than 0.5 pph of poly (sulfonyl) azide based on the total weight of the polymer when the poly ( sulfonyl) has a molecular weight of 200 to 2000. To achieve a measurable rheology modification, the amount of poly (sulfonyl) azide is preferably at least 0.005 pph, preferably at least 0.01 pph, and most preferably at least 0.02 pph pph based on the total polymer.

For coupling, the sulfonyl azide is mixed with the polymer and heated to at least the decomposition temperature of the sulfonyl azide. By decomposition temperature it is meant the temperature at which the azide is converted to the sulfonyl nitrene, removing the nitrogen and heated in the process, as determined by differential scanning calorimetry (DSC). The poly (sulfonyl) azide begins to react at a kinetically significant rate (convenient for use in the practice of the invention) at temperatures of 130 ° C and almost reacts completely at 160 ° C in a DSC (scan at 10 ° C) / min). Acceleration velocity calorimetry (ARC) (scanning at 2 ° C / hour) shows the onset of decomposition which is 100 ° C. The degree of reaction is a function of time and temperature. At the low levels of the azide used in the practice of the invention, the optimum properties are not reached until the essential azide and completely reacts. The temperatures to be used in the practice of the invention are also determined through the softening or melting temperatures of the polymer starting materials. For these reasons, the mixing temperature is advantageously greater than 50 ° C, preferably greater than 80 ° C, and most preferably greater than 90 ° C. The coupling reaction temperature is preferably greater than 90 ° C, preferably greater than 130 ° C and most preferably greater than 150 ° C. Similarly, the coupling temperature is preferably less than 300 ° C, preferably lower 260 ° C and very preferably less than 250 ° C. Preferred times at the desired decomposition temperatures are times which are sufficient to result in the reaction of the coupling agent with the polymer (s) without unpleasant thermal degradation of the polymer matrix. The preferred reaction times in terms of the half-life of the coupling agent, ie the time required for half of the agent to react at a pre-selected temperature, whose half-life can be determined through DSC is 5 lives coupling agent stockings. In the case of bis (sulfonyl) azide, for example, the reaction time of preference is at least 4 minutes at 200 ° C. Conveniently, the polymer and poly (sulfonyl) azide are processed for at least 5, preferably at least 15, most preferably at least 30 seconds, but preferably less than 2 hours, preferably less than 30 minutes and most preferably less than 15 minutes. Preferred processes include at least one of (a) dry blending the coupling agent with the polymer, preferably to form a substantially uniform mixture and adding this mixture to the fusion processing equipment, for example, an extruder to achieve the reaction of coupling, at a temperature of at least the decomposition temperature of the coupling agent; (b) introducing, for example, by injection, a coupling agent in liquid form, for example, dissolved in a solvent therefor or a slurry of the coupling in a liquid, to a polymer-containing device, preferably a molten, melted or fused polymer, but alternatively in the form of a particle, in solution or dispersion, very preferably in a fusion processing equipment; first mixture of a first quantity of a first polymer and a coupling agent, advantageously at a temperature lower than the decomposition temperature of the coupling agent, preferably through mixing under melting, and then forming a second mixture of the first mixture with a second amount of a second polymer (eg, a concentrate of a coupling agent with at least one polymer and optionally other additives, it is conveniently mixed with a second polymer or combination thereof optionally with other additives, to modify the second polymer (s)); (d) feeding at least one coupling agent, preferably in solid form, most preferably finely comminuted, for example, powder, directly into the softened or melted polymer, for example, in the fusion processing equipment, for example , in an extruder; or combinations thereof. Between processes (a) to (d), processes (b) and (c) are preferred, and process (c) is highly preferred. For example, the process (c) is conveniently used to make a concentrate with a first polymer composition having a lower melting temperature, advantageously at a temperature below the decomposition temperature of the coupling agent, and the concentrate is mixed under fusion in a second polymer composition having a higher melting temperature to complete the coupling reaction. Concentrates are especially preferred when the temperatures are sufficiently high to result in the loss of the coupling agent through evaporation or decomposition not leading to the reaction with the polymer, or other conditions could result in that effect. Alternatively, some coupling occurs during the mixing of the first polymer and coupling agent, but some of the coupling agent remains unreacted until the concentrate is mixed in the second polymer composition. Each polymer or polymer composition includes at least one homopolymer, copolymer, terpolymer or interpolymer and optionally includes additives within the skill in the art. When the coupling agent is added in dry form, it is preferred to mix the agent and the polymer in a softened or molten state below the decomposition temperature of the coupling agent to heat the resulting mixture to a temperature at least equal to the decomposition temperature of the coupling agent. The term "melt processing" is used to represent any process wherein the polymer is melting or softening, such as extrusion, pelletization, molding, thermoforming, film blowing, polymer blending in molten form, fiber spinning or combinations thereof. The mixing of the polymer and the coupling agent Conveniently it is achieved through any means within the experience of the technique. The polymers and the coupling agent are suitably combined in any way that results in their desired reaction, preferably by mixing the coupling agent with the polymer (s) under conditions that allow sufficient mixing prior to the reaction to avoid uneven reaction amounts. localized, then subject the resulting mixture to a heat sufficient for the reaction. Preferably, a substantially uniform mixture of the coupling agent and the polymer is formed prior to exposure to conditions where chain coupling occurs. A substantially uniform mixture is one in which the distribution of the coupling agent in the polymer is sufficiently homogeneous to be evidenced by a polymer having a molecular weight consisting of samples taken periodically or in several samples through a production operation or series of experiments using the same starting materials, reagent conditions and amounts after treatment according to the practice of the invention, if the mixing is insufficient, variations are observed due to high molecular weights when the coupling agent is concentrated and the molecular weights low when there is little or no coupling agent. A beneficial effect occurs when, after the treatment according to the practice of the invention, Mw and Mz are higher than the same polymer, which has not been treated with the coupling agent but has been subjected to the same shear stress and thermal history. Thus, preferably, in the practice of the invention, the decomposition of the coupling agent occurs after sufficient mixing to result in a substantially uniform mixture of the coupling agent and the polymer. This mixing is preferably obtained with the polymer in a molten or fused state, ie, above the glass transition temperature, or in a dissolved or finely dispersed condition instead of a solid or particulate mass. The molten or fused form is very preferred to ensure homogeneity instead of localized concentrations on the surface. Any equipment is properly used, preferably a device that provides sufficient mixing and temperature control in the same equipment, but advantageously the practice of the present invention takes place in such devices as an extruder or a static polymer mixing device such as a Brabender mixer. The term "extruder" is used in its broadest meaning and includes devices such as a pellet-extruder or pellet-forming device. Conveniently, when there is a melt extrusion step between the production of the polymer and its use, at least one step of the process of the invention is presented in the melt extrusion step. Although it is within the scope of the invention for the reaction to take place in a solvent or other medium, it is preferred that the reaction in a bulk phase to avoid the last steps of removal of the solvent or other means. For this purpose, a polymer above the crystalline melting temperature is advantageous even for mixing and to reach a reaction temperature (the decomposition temperature of the sulfonyl azide). In a preferred embodiment, the process of the present invention is presented in a single container, that is, the mixing of the coupling agent and the polymer occurs in the same vessel as heating to the decomposition temperature of the coupling agent. The container is preferably a twin screw extruder, but also advantageously is a single screw extruder or an intermittent mixer. The reaction vessel very preferably has at least two zones of different temperatures where a reaction mixture could pass, the first zone advantageously being at a temperature of at least the crystalline melting temperature or the softening temperature of the polymer (s). ) and preferably less than the decomposition temperature of the coupling agents and the second zone being at a temperature sufficient for the decomposition of the coupling agent. The first zone is preferably at a sufficiently high temperature to soften the polymer and allow it to combine with the coupling agent through distribution mixing to a substantially uniform mixture. For polymers that have softening points above of the decomposition temperature (preferably higher than 200 ° C), and especially when the incorporation of a lower melting polymer (such as in a concentrate) is undesirable, the preferred embodiment for the incorporation of the coupling agent is the mixture in solution of the coupling agent in solution or mixture in the polymer, to allow the polymer to be absorbed (absorb or at least absorb some of the coupling agent), and then evaporate the solvent. After evaporation, the resulting mixture is extruded. The solvent is preferably a solvent for the coupling agent, and most preferably also for the polymer. Such solvents include polar solvents such as acetone, THF (tetrahydrofuran), methyl isobutyl ketone and chlorinated hydrocarbons such as methylene chloride. Alternatively, other non-polar compounds are used such as mineral oils wherein the coupling agent is sufficiently miscible to disperse the coupling agent in a polymer. The practice of the process of the invention for coupling polymers produces coupled chain polymers, ie polymers having sulfonamide, coupling between different polymer chains. The resulting polymers advantageously exhibit a higher molecular weight viscosity than the original polymer due to the coupling of long polymer chains to the base structures of the polymer.

The polymers coupled according to the practice of the invention have weight average molecular weights (Mw) increased from those of the starting material by at least 2%, preferably at least 5%, most preferably at least 10% or Mz increased by at least 4%, preferably at least 10% and most preferably at least 20%. Conveniently, the coupled polymers have an Mw less than 300% higher, preferably less than 150%, and most preferably less than 100% more than that of the starting polymer, or Mz correspondingly increased by less than 600%, preferably less than 300%, and most preferably less than 200%. The coupled polymers preferred in this manner have molecular weights of at least 60,000, preferably at least 80,000 and most preferably at least 100,000. Conveniently, these preferred coupled polymers have an Mw less than 500,000, preferably less than 425,000 and most preferably less than 375,000. Those skilled in the art are aware that the particular molecular weight scales of the aromatic polymer are useful for certain applications. See, for example, Encyclopedia of Polymer Science and Engineering, Vol. 16, p. 197 and 203, Second Edition, 1989, John Wiley & amp;; Sons, Inc. For example, foam sheet is made from GPPS with a molecular weight of up to 320,000, while foam beads are made from GPPS with a molecular weight of up to 250,000. However, it is usually inefficient to produce a variety of molecular weights in a production plant due to the time and intermixing of product required to convert from one molecular weight product to another. The practice of the present invention offers the opportunity to produce fewer polymers of different molecular weights in a production polymerization process than desired and to produce, from these polymers, other polymers having a variety of molecular weights. For example, a polymerization plant can produce a product having a first molecular weight and the coupling according to the practice of the invention is useful to produce from that first polymer, a variety of polymer products having different molecular weights greater than those of the first polymer. To achieve a variety of molecular weight products, the coupling agent is used at a variety of levels in the practice of the invention. Similarly, a customer can purchase a polymer of a molecular weight and practice the present invention to prepare polymers of various molecular weights suitable for their applications for polymers. Both applications of the practice of the invention allow a minimal invention since it is unnecessary to prepare or purchase and store a variety of molecular weights of the polymer. Similarly, the practice of the invention facilitates the development of molecular weight beyond but normally achieved in a polymerization process, wherein the molecular weight is limited by the practical or economic kinetics of the free radical polymerization. (The reaction rate could be undesirably slow to obtain high molecular weights. For example, under a set of conditions, the molecular weight increase from 280,000 to 320,000 could result in an increase in the production time of 30%). Another preferred embodiment of the invention is the practice of the invention to form foams. Those skilled in the art recognize that foam properties and / or production are improved through the use of such increments for broad molecular weight polymers, for example, as described by Paquet et al., U.S. Pat. 5,650,106 or through the use of branched polystyrene as described in WO 96/11970. Similar and advantageously superior results are obtained through the coupling before or during a foaming process. In the practice of this invention, the foams are optionally prepared through a medium within the skill in the art, advantageously characterized by mixing, preferably prior to introduction into or into an extruder or other container, a polymer, preferably a polymer of at least one aromatic vinyl monomer and (b) at least 0.005 to 2 pph of a poly (sulfonyl) azide based on the weight of the polymer, and optionally and further including a nucleating agent. A foaming agent is mixed with the polymer and the resulting mixture is advantageously extruded so that the pressure outside the container containing the mixture is less than that in the mixture in the container.

The practice of the foaming process of the invention results in foams, which have properties of an increased viscosity melt strength ratio as demonstrated by the ratio of Mz to Mw increasing with the increasing degrees of poly-azide. (sulfonyl) as compared to those prepared from the same aromatic vinyl foams of starting material, which are not coupled according to the invention. Foams are useful in sound and temperature insulation, foam development and construction, foam manufacturing, craft foam, or packaging. Within the skill in the art, plasticizers polymers are optionally incorporated into the aromatic vinyl polymer material to thereby improve polymer melt processability. Useful plasticizers polymers include low molecular weight polymers of alpha-methyl-styrene or limonene, being d-limonene the preferred limonene. The plasticizing polymer is optionally a copolymer or homopolymer. Useful plasticizers polymers are within the skill of the art as described in the US patent. No. 5,422,378. However, said plasticizer polymers are advantageously used in less quantity or are not necessary to achieve the same plasticizing effect or a similar one with the practice of the present invention. Conveniently a foam is prepared by heating a polymer material to form a plasticized polymer material or molten, incorporating therein a blowing agent to form a foamable gel, and extruding the gel through a die to form the foam product. Prior to mixing with the blowing agent, the polymer material is heated to a temperature at or above its glass transition temperature or melting point. The blowing agent is optionally incorporated or mixed in the melt polymer material by any means known in the art, such as with an extruder, mixer, or the like. The blowing agent is mixed with the melting polymer material at an elevated temperature sufficient to prevent substantial expansion of the melting polymer material and to generally disperse the blowing agent homogeneously therein. Optionally, a nucleator is mixed in the molten polymer or mixed dry with the polymer material before plasticizing or melting. The foamable gel is typically cooled to a lower temperature to optimize the physical characteristics of the foam structure. The gel is optionally cooled in the extruder or other mixing device or in separate coolers, preferably at a temperature above, preferably at least 5 ° C above, preferably up to 40 ° C above the point of softening or the glass transition temperature of the aromatic vinyl polymer.

The gel is then extruded or transported through a die in a desired manner to a zone of reduced or lower pressure to form the foam structure. The lowest pressure zone it is at a lower pressure than that in which the foamable gel is maintained before extrusion through the die. The lower pressure is optionally superatmospheric or subatmospheric (evacuated or empty), but is preferably at an atmospheric level. In the practice of the invention, the polymer is coupled using a poly (sulfonyl) azide, before, during or after mixing with the blowing agent. Conveniently, the coupling agent is mixed with the polymer preferably before or optionally during mixing with the blowing agent and the mixture is heated to at least the decomposition temperature of the poly (sulfonyl) azide for a sufficient period to give as a result the coupling before the foam is formed. Blowing agents (also referred to herein as "foaming agents") useful for making the foam herein include inorganic agents, organic blowing agents, and chemical blowing agents. Suitable inorganic blowing agents include carbon dioxide, nitrogen, argon, water, air, nitrogen, and helium. Organic blowing agents include aliphatic hydrocarbons having 1-9 carbon atoms, aliphatic alcohols having 1-3 carbon atoms, and fully or partially halogenated aliphatic hydrocarbons having 1-4 carbon atoms. The aliphatic hydrocarbons include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, and combinations thereof. Aliphatic alcohols include methanol, ethanol, n-propanol and isopropanol. The fully or 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-tetrafluoroethane (HFC-134a), 1, 1, 2,2-tetrafluoromethane (HFC-134), pentafluoroethane, difluoromethane, perfluoroethane, 2,2-difluoropropane, 1,1,1-trifluoropropane, perfluoropropane, dichloropropane, difluoropropane, perfluorobutane, perfluorocyclobutane. Chlorocarbons and partially halogenated chlorofluorocarbons for use in this invention include methyl chloride, methylene chloride, ethyl chloride, 1,1-trichloroethane, 1,1-dichloro-1-fluoroethane (CFC-141b), 1-chloro-1, 1-difluoroethane (CFC-142c), chlorodifluoromethane (CFC-22), 1,1-dichloro-2,2,2-trifluoroethane (CFC-123) and 1-chloro-1,2, 2,2-tetrafluoroethane (CFC-124). Fully halogenated chlorofluorocarbons include trichloromonofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trichlorotrifluoroethane (CFC-113), 1,1-trifluoroethane, pentafluoroethane, dichlorotetrafluoroethane (CFC-114), chlorheptafluoropropane, and dichlorohexafluoropropane. Chemical blowing agents include azodicarbonamide, azodiisobutyronitrile, benzenesulfonhydrazide, 4,4-oxybenzenesulfonyl-semicarbazide, p-toluenesulfonyl-semicarbazide, barium azodicarboxylate, N, N'-dimethyl-N, N'-dinitrosoterephthalamide, and trihydrazino triazine. Although the process of the present optionally employs any blowing agent, the process is particularly useful with blowing agents exhibiting high vapor pressure and low solubility in aromatic monovinyl polymer melting baths. Such blowing agents include carbon dioxide and 1,1,1,2-tetrafluoroethane (HCF-134a). Preferred blowing agents include carbon dioxide, water, aliphatic alcohols having 1-3 carbon atoms, aliphatic hydrocarbons having 1-9 carbon atoms, 1,1-difluoroethane (HFC-152a), 1, 1, 2 -tetrafluoroethane (HFC-134a), 1,1, 2,2-tetrafluoroethane (HCF-134), other fully or partially halogenated aliphatic hydrocarbons and combinations thereof. A particularly useful blowing agent system is one that completely comprises carbon dioxide. The amount of blowing agent incorporated in the polymer melt to make a foaming polymer gel is 0.2 to 5.0 gram-moles per kilogram of the polymer, preferably 0.5 to 3.0 gram-moles per kilogram of polymer, and most preferably from 1.0 to 2.50 gram-moles per kilogram of polymer. A nucleating agent is optionally added to control the size of the foam cells. Preferred nucleating agents include inorganic substances such as calcium carbonate, talc, clay, titanium dioxide, silica, barium stearate, calcium stearate, diatomaceous earth, mixtures of citric acid and sodium bicarbonate. The amount of nucleating agent employed advantageously varies from 0.01 to 5 parts in weight per 100 parts by weight of a polymer resin. The preferred scale is 0.1 to 3 parts by weight. The foam of the present invention preferably has a density of 16 to 250 kilograms per cubic meter measured in accordance with ASTM D 1622-88, most preferably a density of less than 65 kg / rr? T Preferably, the foam has a lower density than that of a foam made from the foamed starting material polymer through the same process but without the treatment by the practice of the invention. The foam preferably has an average cell size of 3 mm or less measured according to ASTM D3576-77. The foam preferably retains physical properties such as crack resistance as measured by ASTM D1621-79 or flexibility as measured by ASTM C203 or a combination thereof as compared to that of a polymer of the same untreated starting materials in accordance with the practice of the invention. Most preferably, by treating the polymer starting materials through the process of the invention, at least a higher polymer production in the foam (eg, in kilograms per hour) or a lower density than with the materials can be achieved. starting materials not treated in the same foaming process while retaining equivalent or better crack resistance or flexibility, or both. The foam optionally takes any physical configuration known in the art such as sheet or plank. The foam is particularly suitable to be formed through extrusion to a board, desirably having a cross-sectional area of 30 square centimeters (cm2) or more, and a smaller dimension in cross-section (thickness) preferably 0.95 centimeters or more. The foam is also conveniently extruded in the form of a sheet with a transverse thickness of less than 0.95 centimeters and a cross-sectional area of 10 cm2 or more. The foam is optionally closed cell or open cell. The preferred closed cell foams have more than 90% closed cell content measured in accordance with ASTM D2856-87. Various additives are optionally incorporated into the foam structure such as inorganic fillers, pigments, anti-oxidants, acid scavengers, ultraviolet light absorbers, flame retardants, processing aids, extrusion aids and combinations thereof. The foam is optionally used to insulate a surface by applying an insulating panel made of foam to the surface. These panels are useful in any conventional insulation application such as ceilings, buildings, refrigerators, etc. The following examples are to illustrate this invention and to limit it. The relationships, parts and percentages are by weight unless otherwise indicated. The examples (Ex.) Of the invention are designated numerically, while the comparative samples (M.C.) are designated alphabetically and are not examples of the invention.

Examples 1-8 and Comparative Samples AC The general purpose and the high impact polystyrenes indicated in Table 1 were mixed by stirring with the indicated charges of azide of 4,4'-oxybis (benzenesulfonyl), hereinafter "azide of poly (sulfonyl) ", using 1400 PPM of mineral oil as a thickening agent. The mixtures were combined in a co-rotating, co-rotating twin-screw extruder of 30 mmr at a lower temperature in the extruder and with a melting temperature of 240 ° C near its terminus. The same polystyrene was combined without the azide under the same conditions for comparison. During the extrusion process, observation of the extruded polymer product showed that the melt strength increased and an increase in viscosity was indicated through an increase in extruder pressure. Molecular weights (Mw and Mz, as determined by gel permeation chromatography) were increased as much as 48% and 88%, respectively. These data indicate that the coupling was introduced into the various polymers.

TABLE 1 * A plasticizer containing general purpose polystyrene commercially available from The Dow Chemical Company under the trade name of Styron666D, general purpose polystyrene, which is commonly used for injection molding and has melt flow rate properties according to ASTM 1238 (MFR) 8 g / 10 minutes at 200 ° C using a weight of 5 kg. ** General purpose polystyrene containing no plasticizer, commercially available from The Dow Chemical Company under the trade name Styron685D, general purpose polystyrene, which is commonly used to make foamed polystyrene sheets and oriented polystyrene sheets and has properties of MFR 1.5. *** A high impact polystyrene plasticizer commercially available from The Dow Chemical Company under the tradename Styron484, polystyrene which is commonly used for extrusion applications and has Vicat heat distortion temperature properties of 101 ° C, MFR 2.8. _ __. _ Examples 9-12 and Comparative Samples D and E: Example of the Molecular Weight Changes in Viscosity Resulting from the Practice of the Invention Examples 9-12 and Comparative Samples D and E represent the application of the invention to modify the properties of a material of polystyrene foam, a polystyrene with a nominal molecular weight of 135,000. The starting material was prepared using three 22-liter plug flow reactors in series for the next polymerization: the reactors were equipped with stirrers to ensure mixing and a good heat transfer, as well as heating and cooling jackets to maintain the polymerization mass at the given temperatures. The temperature profiles of the three reactors were as follows: Inlet feed temperature 100 ° C Reactor 1 Zone 1 115 ° C Zone 2 115 ° C Zone 3 115 ° C Reactor 2 Zone 1 130 ° C Zone 2 145 ° C Zone 3 155 ° C Reactor 3 Zone 1 164 ° C Zone 2 175 ° C Zone 3 175 ° C The first feed of 97% by weight of styrene, 3% by weight of ethylbenzene and 25 ppm of initiator commercially available from Akzo Novel under the tradename Triganox ™ was continuously fed to zone 1 of the first reactor at a rate of 8.6 kg. /hour. The polymerization was continued through zones 2 and 3. The mixture of zone 3 of the first reactor was continuously fed to zone 1 of the second reactor together with a second feed. The second feed consisted of 98.8% by weight of ethylbenzene and 1.2% by weight of n-dodecyl mercaptan, and feeding was continued at a rate of 1.2 kg / hour. Polymerization was completed through the subsequent zones of the second and third Reactors, followed by devolatilization in a vacuum devolatilizer operating at an absolute pressure of 20 mm Hg (2.7 kPa) and 225 ° C. The production of the devolatilizer was 4.25 kg / hour. In Examples 9-12, the amounts of the poly (sulfonyl) azide designated in Table 1, was reacted with the foam material according to the procedure of Example 1, except that the extruder size was 40 mm. The foam was not made with these examples. The data are in Table 2A. Comparative Sample D was the material before it was processed in a twin-screw extruder, and Comparative Sample E was the result of processing the material and shows the typical degradation of Mw (and other molecule weight properties) due to the thermal conditions of the processing in the twin screw extruder. However, rheological measurements (shear stress and extension viscosities) were performed for Comparative Samples E and Examples 11 and 12. These data are summarized in Table 2-B. In the Tables "Azide" refers to 4,4'-oxybis (benzenesulfonyl) azide.

The comparison of the viscosity of polystyrene with a molecular weight of 135,000 without coupling according to the practice of the invention and with 1000 and 2000 ppm of 4,4'-oxybis (benzenesulfonyl) azide on a frequency scale of 1E-02.5 at 1E + 03 rad / seconds as obtained using a capillary rheometer commercially available from Rheotens Corp., according to the manufacturer's instructions or according to the procedures of ASTM D 3835-96 at a temperature of 180 ° C shows that the viscosity The low frequency of the coupled material was greater than that of the starting material, but the viscosities converge and become almost equal by 1E + 02 rad / second. A convenient means to compare the viscosity of different samples is through a ratio. In Table 2-B, the base sample was polystyrene with a molecular weight of 135,000 untreated (Comparative Sample D). The relationships were provided at various shear rates. The relationships with values greater than 1, indicate that the treated material has a higher viscosity than the untreated polystyrene and the relationships with values less than 1, indicate the opposite effect.

TABLE 2-B Effect of the Azide on the Viscosity of Polystyrene with a Weight These data show, for example, that 1000 ppm of azide which reacts with polystyrene with a molecular weight of 135,000 increased the shear viscosity to 63% when compared to a shear rate of 0.01 rad / seconds and 180 ° C, and 2000 ppm of azide increased the shear viscosity by 25% when compared to 0.01 rad / seconds and 180 ° C. In addition, the shear viscosity ratio approached 1 as the shear rate increased to 100 rad / sec.The reaction of poly (sulfonyl) azide with polystyrene with a molecular weight of 135,000. shows that the viscosity of extension increased substantially for both levels of azide.The higher extension viscosity imparted more resistance to the polymer as it expanded to a foam.

Examples 13-15 and Comparative Samples F and G: Foams The polymer used was the general purpose polystyrene used as starting material in Examples 9-12 and Samples Comparatives D and E, which had the properties of melt flow rate (MFR) according to ASTM 1238 of 25 g / 10 in a 200 ° C and using a weight of 5 kg. The polymer was fed to a pilot scale foam extrusion line at a rate of 2.3 kg / hour for a period of at least 4 hours or until it was completely representative of the polymer in the foam line. The pilot scale foam line consisted of a 25 mm single screw extruder that melted and mixed the solid additives and the polymer to a melt bath, and the melt was pumped through the process. The melting bath was then mixed with the blowing agent, in this case carbon dioxide. The resulting gel (polymer, additives and blowing agent) was then cooled using, for example, static mixer coolers, manufactured by Koch or rotary coolers for dynamic cooling. This cooling step led to the gel at a uniform temperature (foaming temperature) before it was supplied to the configuration die. The configuration die maintained proper pressure control for expansion to a foam and was set to a desired cross section (thickness and width). The system volume of the pilot scale foam line from the feed to the extruder to the discharge of the die configuration required 15 minutes at a feed rate of 2.3 kg / hour. Typically, 3-4 system volumes (residence volumes) were needed to observe the effects of the process conditions to make a foam in a stable mode. Blowing agent, carbon dioxide added, at a speed of 4 parts per 100 parts of polystyrene (0.1 kg / hour) using a positive displacement pump with enough head pressure to keep the carbon dioxide in a liquid state of compression. No other additives of a typical foam formulation were used. For Comparative Samples f and G, control formulations without sulfonyl azide were made at foaming temperatures of 130 ° C and 140 ° C, respectively. The pressure of the die was determined through pressure transducers at the entrance to the configuration die and the die pressure was regulated by adjusting the opening of the die through mechanical means. For examples 13-15, the polystyrene in batches of 15 kg was thickened with 1000 ppm of mineral oil by stirring the two materials thoroughly in a plastic bag. The careful addition of the mineral oil under continuous stirring was used to ensure a uniform coating of the polystyrene by the mineral oil. Then, the thickened polystyrene was mixed with 1000 ppm of the poly (sulfonyl) azide using the same mixing scheme to ensure a uniform coating of the polystyrene thickened by the azide. This prepared the material as feed to the extruder. Sulfonyl azide was fed at 1000 ppm (0.0023 kg / hour) carried in the coated polystyrene at each of the foaming temperatures of the control formulation and with equivalent die pressures. Dothole readings were made using a micrometer (linear gauge) attached to the mechanical adjustment of the die. The gauge was adjusted to the fully closed position before starting the experiments. Foam samples were obtained for each condition. Measurements of foam property density (ASTM D 1622), thickness, and cell size (ASTM D 3576), as well as changes in molecular weight (gel penetration chromatography) were measured to determine the influence of the reaction of azide on polystyrene. These results are summarized in table 3. to O TABLE 3 Experimental Foaming Results Summary *. • ^ residence refer to the processing period for this formulation. There was the number of 15-minute periods in this condition. It is illustrated how the reaction influenced the properties of the polystyrene after the respective process period.

The data summarized in Table 3 show that the reaction of poly (sulfonyl) azide and polystyrene caused a significant and unexpected increase in the molecular weight properties of polystyrene. In addition, the new molecular weight properties provided a benefit to the foam properties by improving the melting strength properties of the gel. This was demonstrated through increases in Mw and Mz measurements for polystyrene (in the foam) and increased die gap to maintain a comparable die pressure. Also, the cell size and the thickness of the foam were increased, compared to the unmodified polystyrene foam, demonstrating the increased extension character as a result of the properties of the modified polystyrene. Note that the molecular weight increase of the C.S. to the Examples of the invention was comparable with studies without foaming. It was also shown that the process temperatures for foaming have no influence on the molecular weight of the polystyrene. In addition, the increase in foam density at the temperature of 140 ° C was an indication that the higher molecular weight of the polystyrene modified by the sulfonyl azide resulted in an increased melt tension, and a greater resistance to expansion. This resistance is optionally reduced by increasing the foaming temperature, so that the foaming density falls as illustrated by the densities of the two Comparative Samples F and G. The data show that the molecular weight properties continued to change after 4 residence volumes of the foam extrusion system. This was not due to a longer reaction time, but rather to the time required to purge the unmodified polystyrene foam line and the extruded foam product being representative of the polystyrene modified with 1000 ppm sulfonyl azide, as described previously.

Claims (10)

1. - A process comprising the steps of: (1) forming a mixture of (a) an aromatic vinyl polymer and (b) a coupling amount of at least one poly (sulfonyl) azide; (2) introducing the aromatic vinyl polymer or mixture to a fusion processing device; (3) melting the aromatic vinyl polymer or mixture, and then (4) exposing the mixture at a temperature, and thereafter, at the melting process temperature, sufficient to result in the coupling of the aromatic vinyl polymer.

2. The process according to claim 1, wherein the amount of coupling is from 0.005 pph to 2 pph based on the amount of aromatic vinyl polymer; the aromatic vinyl polymer is a styrene polymer; and the melting process temperature is greater than 150 ° C and below 250 ° C.

3. The process according to claim 1, wherein the mixture going in step (4) further comprises a blowing agent and the process further comprises the steps of extruding the resulting mixture into an area having a higher pressure. lower than the pressure of step (4), cool the mixture and form a resulting foam.

4. The process according to claim 1, wherein at least one poly (sulfonyl) azide has a structure X-R-X, wherein each X is S02N3 and R represents a hydrocarbyl not substituted or inertly substituted, hydrocarbyl ether or a group containing silicon; wherein the poly (sulfonyl) azide has sufficient carbon, oxygen or silicon atoms to separate the sulfonyl azide groups sufficiently to allow an easy reaction between the aromatic vinyl polymer and the sulfonyl azide; and wherein R includes at least one aryl group between the sulfonyl groups.

5. The process or composition according to any of claims 1-4, wherein a substantially uniform mixture of poly (sulfonyl) azide and polymer is formed prior to exposure to conditions where chain coupling occurs.

6. A process for increasing the molecular weight of an aromatic vinyl polymer by heating the mixture of at least one aromatic vinyl polymer and a coupling amount of at least one poly (sulfonyl) azide.

7. A process comprising the steps of: (1) forming, under a first pressure, a mixture of an aromatic vinyl polymer, a blowing agent and at least one poly (sulfonyl) azide, with the mixture a a temperature at which the viscosity of the mixture is sufficient to retain the blowing agent when the mixture is allowed to expand; (2) Extrude the mixture to a support zone maintained at a temperature or a second pressure, which does not allow the mixture to foam, the support zone having an outlet die which defines an orifice opening in an area of a third pressure lower than the first or second pressures at which the mixture is foamed, and a gate that can be opened by closing the die orifice; (3) Periodically open the gate; (4) Substantially and concurrently apply mechanical pressure through a moving ram on the mixture to expel the mixture from the support zone through the die orifice towards the zone of the third pressure, at a speed greater than that at which substantial foaming occurs in the die orifice and less than that at which substantial irregularities occur in the transverse area or shape; and (5) allowing the ejected mixture to expand without restriction in at least one dimension to produce an elongate thermoplastic cell body.

8. A composition comprising a foam or polymer prepared through a process of any of claims 1-7.

9. An article comprising a composition of claim 8.

10. The article according to claim 9 in the form of sound insulation or temperature, development or construction foams, manufacturing foam, craft foam, flotation foam, or packing. SUMMARY The invention includes a process comprising the steps of: (1) forming a mixture of (a) an aromatic vinyl polymer and (b) a coupling amount of at least one poly (sulfonyl) azide; (2) introducing the aromatic vinyl polymer or mixture into a fusion processing device; (3) melting at least the aromatic vinyl polymer or mixture, and then (4) exposing the mixture at a temperature, hereinafter, the melting process temperature, sufficient to result in the coupling of the vinyl polymer aromatic. The invention also includes a process for increasing the molecular weight of an aromatic vinyl polymer by heating a mixture of at least one aromatic vinyl polymer and a coupling amount of at least one poly (sulfonyl) azide. Alternatively, the invention is a process comprising the steps of: (1) forming, under a first pressure, a mixture of an aromatic vinyl polymer, a blowing agent and at least one poly (sulfonyl) azide, with the mixing at a temperature at which the viscosity of the mixture is sufficient to retain the blowing agent when the mixture is allowed to expand; (2) extrude the mixture to a support zone maintained at a temperature and a second pressure, which does not allow the mixture to foam, the support zone having an outlet die defining an orifice opening towards an area of a third pressure less than the first and second pressures at which the mixture is foamed, and a gate that can be opened by closing the die orifice; (3) Periodically open the gate; (4) Substantially and concurrently applying mechanical pressure through a moving ram over the mixture to eject the mixture from the support zone into the die orifice of a third pressure, at a rate greater than that at which substantial foaming occurs. in the die hole and smaller than that at which substantial irregularities occur in the transverse area or shape; and (5) allowing the ejected mixture to expand without restriction in at least one dimension to produce an elongate thermoplastic cell body. The invention also includes any composition comprising a product formed through a process of the invention, said composition preferably comprising a foam or polymer and any article formed from said composition.