Abstract: A horizontal vacuum extrusion line includes a fixed bulkhead, a die inside the bulkhead, a telescoping vacuum chamber section and a fixed chamber section. A dam in the fixed section forms a pond for immersion cooling of the extrudate. A truss extends from the dam to the bulkhead supporting, shaping and calibration equipment and extends through the telescoping section. Fluid pressurizable seals at each end of the telescoping section are operable after the telescoping section is closed against the bulkhead and the telescoping and fixed sections are locked together. The telescoping section provide a more compact line and easier access to the complex equipment downstream of the die. The extrudate from the die passes down into the pond and then through an orifice in a hood projecting from the chamber into a lower level portion of the pond exposed to atmosphere. The hood also includes a tractor drive to push the extrudate through the underwater orifice.

Abstract: By kneading a composition containing a filler and an organic forming binder, extruding the composition, baking the composition in a non-oxidizing atmosphere, there is obtained a first baked lead containing, as a binder, a carbon obtained by the carbonization of the organic forming binder. Then, by heating the first baked lead in an oxidizing atmosphere to remove the binder carbon, there is formed a second baked lead composed of at least the filler. The pores of the second baked lead are impregnated with a solution containing perhydropolysilazane, subjecting the lead to a heat treatment in an inert atmosphere or an ammonia gas atmosphere to form a third baked lead containing the resultant silicon nitride. Finally, ink is filled into the pores of the third baked lead to provide a baked color pencil lead.

Abstract: A process for fabricating an article having a rigid foam core and a resilient outer plastic shell by extruding a heated thermoplastic material to form the shell, partially hardening the extruded plastic shell, injecting a liquid foam material into the interior of the partially hardened plastic shell, and cooling the shell and the liquid foam material to fully harden the plastic shell and the foam under conditions which cause the article to have a predetermined shape and size.

Abstract: An apparatus are described for extruding a soft, low density elastomeric thermoplastic foam. A single screw extruder having a very large screw length to diameter ratio is provided to thoroughly mix the thermoplastic elastomer with a blowing agent. A thin, substantially taperless die is also provided to form extruded profiles. By using such an apparatus, a variety of complex-shaped extruded profiles may be easily produced.

Abstract: A thermosetting foam, preferably polyisocyanurate or polyurethane foam, is prepared in an extruder which permits the incorporation of high levels of filler particles. The method includes introducing polyol, isocyanate and filler particles to an extruder screw for mixing. In conjunction with extruding, a catalyst is added. The catalyst may be added either in a last extruder barrel or with the extruder head. Foam with filler particle content in excess of 12% made be readily made. Filler particles, such as aluminum trihydrate, perlite, carbon black, diatomaceous earth, polyiso powders, ammonium phosphate, fly ash, barium sulfate, calcium silicate, and calcium carbonate, may be used. The process described is preferably used for making foam boards or bunstock.

Abstract: A laminar flow process for preparing cellulose diacetate fibers is disclosed. In the process, a precipitation-acid stream and an acid-dope stream are contacted in a zone having substantially laminar flow. The acid-dope stream is annularly disposed within and flows in the same direction as the precipitation-acid stream. The precipitation-acid stream has a temperature of 100.degree. to 200.degree. F. and comprises 25 to 35 percent by weight acetic acid and 75 to 65 percent by weight water. The acid-dope stream has a temperature in the range of 100.degree. to 200.degree. F. and comprised of 5 to 22 weight percent of cellulose diacetate having an inherent viscosity of at least 1.0, and 95 to 78 percent by weight of a mixture comprising 65 to 90 weight percent acetic acid and 35 to 10 weight percent water. The precipitation-acid stream has a linear flow greater than or equal to the linear flow of the acid-dope stream. The weight ratio of the precipitation-acid stream to the acid-dope stream is at least 9:1.

Abstract: The triple coextrusion of snack food products having highly uniform and integral individual layers is achieved by the use of a compact, precisely toleranced coextrusion die which may be mounted at the outlet end of a cooker extruder. The coextrusion die includes a die block with smooth, unobstructed flow passages for each material. The outer passages for the casing material are substantially coaxial with the central axis of the die block and extend from end to end. A central bore and an annular passage having their central axes aligned with the central axis of the die block at its outlet end extend upstream to filler feed ports. The feed port entrances are at the outer surface of the die block between its ends. The side ports and filler feed lines connected to them do not interfere with a substantially straight flow path of casing material directly from a cooker extruder. A protruding tip formed at the outlet end of the die block by the bore and annular passage extends into a converging block or cone.

Abstract: A structurally rigid biodegradable foam scaffold useful for cell transplantation is provided. The foam can be loaded with nutrients and/or drugs that elute from the foam during transplant to promote growth of the cells. The foam, which features a continuous network of pores, is fabricated using a novel method involving phase separation and consequent expansion upon sublimation of a liquid solvent, preferably naphthalene.

Abstract: A PC strand is formed by twisting peripheral wires made of deformed PC steel wires around a core, and allowing rust inhibitive material of thermoplastic resin to permeate into voids defined among the core and peripheral wires by use of an extruder. Since at least one of the core and peripheral wires is made of a deformed PC steel wire having an uneven outer surface, the thermoplastic resin can smoothly permeate deep into the inside of the PC strand.

Abstract: A method for fabricating composite structures at a low-cost, moderate-to-high production rate. A first embodiment of the method includes employing a continuous press forming fabrication process. A second embodiment of the method includes employing a pultrusion process for obtaining composite structures. The methods include coating yarns with matrix material, weaving the yarn into fabric to produce a continuous fabric supply and feeding multiple layers of net-shaped fabrics having optimally oriented fibers into a debulking tool to form an undebulked preform. The continuous press forming fabrication process includes partially debulking the preform, cutting the partially debulked preform and debulking the partially debulked preform to form a net-shape. An electron-beam or similar technique then cures the structure. The pultrusion fabric process includes feeding the undebulked preform into a heated die and gradually debulking the undebulked preform.

Abstract: A coextruded block composite which includes a porous first block. The block is permeable to fluids and includes a granular component and a binder component. The block has interconnected pores therethrough having a first average diameter. The composite also includes a second block. In addition, at least one of the first block and the second block is continuous and at least a portion of the second block is contiguous with at least a portion of the first block. The second block also may be permeable to fluids. Additional blocks may be present, if desired. One or more of the blocks other than the first block may be a porous block having a granular component and a thermoplastic binder component. The coextruded block composite may be employed as a filter medium.

Abstract: A process for fabricating an article having a rigid foam core and a resilient outer plastic shell by extruding heated thermoplastic material to form the shell, partially hardening the extruded a plastic shell, injecting a liquid foam material into the interior of the partially hardened plastic shell, and cooling the shell and the liquid foam material to fully harden the plastic shell and the foam under conditions which cause the article to have a predetermined shape and size.

Abstract: A secondary coating line for producing a secondary-coated optical fibre or bundle of fibres, the line including a feeding apparatus with a feed roll for feeding an optical fibre or bundle of fibres; an extruder for extruding an oversize secondary jacket around the fibre or bundle of fibres; a cooling apparatus for cooling the extruded secondary jacket, the distance between the extruder and the point where the cooling apparatus starts to cool being adjustable; and a winding apparatus for winding the finished secondary-coated fibre or bundle of fibres on a take-up roll.

Abstract: An anhydride-containing thermoplastic resin such as a styrene maleic anhydride copolymer is processed in a vented extruder in the present of a nitrogenous chemical blowing agent to both imidize at least a portion of the anhydride groups and remove volatile residues such as unreacted styrene monomer from the resin.

Abstract: This invention provides a continuous profile comprising a crosslinked foam matrix and a continuous filament embedded within the matrix. The profile is prepared by 1) extruding in an upward direction a composite consisting essentially of a foamable and crosslinkable composition containing a continuous filament, followed by 2) crosslinking and foaming the composition while the composition is in a substantially non-flowing state and supported by the filament.

Abstract: In a process for extruding a low density foam, a foamable thermoplastic elastomer such as a thermoplastic rubber is selected. The selected thermoplastic elastomer is then fed into a heated extruder barrel where it is compressed and melted by the action of a screw. A blowing agent consisting of water is introduced into the melted thermoplastic elastomer. The melted thermoplastic elastomer and the water are thoroughly mixed and then cooled to a uniform, predetermined temperature. The mixture is then forced through a die to form an extruded foam profile.

Abstract: A process for the manufacture of a multilayer, cross-linked, heat shrinkable, polyolefin film, the film having at least one inner layer including a thermoplastic polymer sandwiched between two outer layers including a thermoplastic polymer different from the thermoplastic polymer of the inner layer, including the steps of coextruding the polymers into a tape; cross-linking the tape; and converting the cross-linked tape into a heat shrinkable film by orientation; wherein scrap material produced in the manufacture of the heat shrinkable film is incorporated by recycling the film into the coextrusion step in an amount up to 50% by weight of the total film weight.

Abstract: A white-colored porous polymer film having elongated spherical pores, which is characterized in that said pores exposed on a surface created by cutting the film along longitudinal direction satisfy the following formulae, possesses a low density, good surface and mechanical property and good processability: ##EQU1## wherein, P.sub.L,90 is an average length of longer axes of 90% or more of the exposed pores;P.sub.D,90 is an average length of shorter axes of 90% or more of the exposed pores;P.sub.L/D,50 is an average of the longer axis to the shorter axis length ratios of the exposed pores;P.sub.N is the number of exposed pores per 1000 .mu.m.sup.2 of the exposed surface; andP.sub.A is the ratio of the exposed pore area to the exposed surface area.The polymer film of the present invention comprises a polyester and polyolefin resin mixture, inorganic particles, a metal sulfonate and a hindered phenol.

Abstract: Foam forming techniques capable of permitting foaming of biodegradable resin to be positively and uniformly accomplished to provide a biodegradable resin foam with satisfactory quality. The biodegradable resin foam is made of biodegradable resin consisting of a main biodegradable resin ingredient of 100.degree. C. or more in melting point and a low-melting biodegradable resin ingredient of 100.degree. C. or less in melting point. The biodegradable resin foam is produced by placing a starting material consisting of at least biodegradable resin and a substantial amount of moisture in a heated and pressurized environment, releasing the starting material from the environment to foam the biodegradable resin, and subjecting the foamed resin to forming by means of a forming mold. An apparatus for producing the foamed biodegradable resin foam includes a pressure adjusting chamber, an air-permeable forming mold, a pressure reducing tank and an injection machine.

Abstract: A method of manufacturing an electric wire insulated with a foamed plastic. The method includes steps of introducing a foaming agent into a fluororesin in a molten state to allow the foaming agent to dispersed in the molten resin, and extruding the molten resin having the foaming agent dispersed therein onto a conductor wire to allow foaming. A fluorine-based foaming agent contains as a main component at least one kind of a fluorocarbon having a molecular weight of about 338 to 488 is used as a foaming agent.

Abstract: A method of fabricating a controlled and uniform cell size blotter roll for blotting liquid images consisting of toner particles and carrier liquid. The method includes the step of mixing a first grade of salt having first particles of a first uniform size with a polymer material so as to form a first mixture. The method next includes a step of extruding the first mixture to form an extruded sleeve having intimately compacted polymer material and salt particles, an outer surface, and an inner surface defining a hollow interior.

Abstract: A plastic foam material composed of a blended resin composition which includes at least two thermoplastic resins and a silane-modified based resin. The blended resin composition consists essentially of 100 parts by weight of at least two thermoplastic resins, from about 1 to about 50 parts by weight of a silane-modified, cross-linked, thermoplastic resin; from about 0.001 to about 2.5 parts by weight of a cross-linking catalyst for use in a silane compound and from about 1 to about 20 parts by weight of a foaming agent. According to one embodiment of the present invention, the thermoplastic resins include at least two substantially incompatible and substantially uncross-linked thermoplastic resins, while in another embodiment the two thermoplastic resins need not be substantially incompatible. The blended resin composition may further include reinforcers such as glass fibers and filler. The thermodecomposition foaming agent decomposes at sufficiently high temperatures to yield a plastic foam material.

Abstract: The invention provides a method and apparatus for forming a large cured reinforced composite structure. The method comprises placing at least one reinforcing fiber mat or fabric into a desired form and enclosing the fiber mat or fabric within a sealed envelope which contains a vacuum port and a resin supply conduit. The supply conduit introduces a curable resin at a rate not to exceed the rate of evacuation. The envelope is filled and the resin is cured.

Abstract: A resin laminate of the invention includes a sheet laminate including a skin, which is securely joined with a foamed bead base by heating. The resin laminate is manufactured according to the following steps. The foamed bead base and the sheet laminate consisting of the skin, a foam layer, and a thermoplastic resin film are prepared separately. The thermoplastic resin film is made of a resin material which thermally adheres to both the foam layer and the foamed bead base and has a softening temperature lower than those of the foam layer and the foamed bead base. The thermoplastic resin film is softened by heating the sheet laminate, which is then softened by heating the sheet laminate, which is then pressed against and bonded to the foamed bead base by vacuum molding or press forming. The thermoplastic resin film thermally adheres to both the foam .layer of the sheet laminate and the foamed bead base, thus joining the sheet laminate with the foamed bead base.

Abstract: A process for the continuous production of a high modulus article comprising a composite of an oriented plastic material and an oriented particulate material, said process including the steps of:a. continuously forcing an orientable plastics material, while it is close to or at its softening temperature and in admixture with an orientable particulate material, through a converging passage of which the cross-sectional area diminishes in the forward direction of plastic flow, thereby to produce an extrudate;b. deforming the extrudate, while it is maintained at or close to its melt temperature, to produce an oriented, deformed extrudate; andc. cooling the deformed extrudate to preserve the orientation and provide said composite. The foamed and unfoamed composite articles have strength, modulus and density values comparable to typical hardwoods or softwoods.

Abstract: Disclosed is a process for making a thermoplastic polymer foam structure with a blowing agent having water. The process comprises in sequence: a) melting the polymer to form a polymer melt; b) incorporating a brominated aliphatic fire retardant into the polymer melt; c) incorporating and mixing a first blowing agent into the polymer melt to form a first foamable gel; d) cooling the first foamable gel to a suitable foaming temperature; e) incorporating and mixing a second blowing agent comprising water into the cooled first foamable gel to form a second foamable gel; f) optionally further cooling the second foamable gel to a suitable foaming temperature; and g) extruding the second foamable gel through an extrusion die to form a foam structure. Incorporating of the water blowing agent downstream in the process after the foamable gel has been cooled reduces or minimizes process corrosion problems. Further disclosed is an apparatus for making the foam structure.

Abstract: A process for making gas separation membranes having enhanced selectivity for a mixture of gases is disclosed. The membranes may be asymmetric or multicomponent. The membranes surprisingly provide selectivity for gases in a mixture that approaches the relative selectivity of the single gas components. Preferably the membrane provides selectivity for a mixture of gases which is at least 65%, preferably 80%, of the relative selectivity of the corresponding single gases.

Abstract: Improved insulative cable assemblies and methods for producing them are disclosed. The insulative cable assemblies comprise a conductor housed within a polymeric insulation layer expanded with expandable thermoplastic microspheres. The use of a relatively inelastic outside sheath controls the expansion of the insulative layer and assures a snug fit between the insulation and the conductor. The insulation layer is highly resilient and resistant to dielectric changes due to compression or damage from mechanical manipulation of the cable. Additionally, the ability to expand the insulative layer after cable assembly is completed provides far greater freedom in cable processing without compromising low dielectric constant.

Abstract: Porous pipe formed of particles of vulcanized rubber dispersed in a binder resin such as polyethylene are stabilized to reduce degradation by ultraviolet light by dispersing in the binder resin an effective amount of an ultraviolet stabilizer such as 0.1 to 10% by weight of carbon black.

Abstract: A method for preparing a thermosetting foam, such as polyisocyanurate or polyurethane foam, includes introducing polyol and isocyanate to a screw of an extruder and mixing in the extruder screw. Catalyst is then added and mixed with the already formed mixture in the extruder screw. This mixture is extruded onto a conveyor and foamed on the conveyor. Finely divided carbon black, dispersing agent and/or surfactant may be mixed with polyol before introducing to the screw of the extruder or carbon black may be dispersed in polyol in the extruder and a polyol premix made before the remainder of the polyol is added. Foam cell size is decreased when extruder speed is increased. The foaming agent, which is preferably HCFC or water, may be mixed with one of the components, preferably the polyol, before introducing to the screw of the extruder. The mixture is cooled before extruding onto a conveyor to delay the foaming step until the mixture is outside the extruder.

Abstract: In producing a foam insulated electric wire having an insulating layer made of a polyolefin foam, a foaming agent is employed, which is a liquid mixture of at least two kinds of compounds selected from the group consisting of ethers, esters, ketones and saturated hydrocarbons having boiling points of 100.degree. C. or below, or a liquid mixture of at least one kind of compound selected from the group consisting of ethers, esters, ketones and saturated hydrocarbons having boiling points of 100.degree. C. or below and at least one kind of liquid compound selected from the group consisting of ethers, esters, ketones, saturated hydrocarbons and alcohols having boiling points higher than 100.degree. C. but not exceeding 150.degree. C. Thus, a foam insulating layer having a high cell content and a low deformation ratio become available. Since the foam insulating layer has a high cell content and a low deformation ratio, the foam insulating layer, if reduced in diameter, is hardly squeezed.

Abstract: A method of making an elastomeric, hot-melt adhesive foam is disclosed. The method involves melting an adhesive material, mixing a gas with the adhesive material under pressure to form a solution of the gas in the adhesive material, reducing the pressure to cause evolution and/or expansion of the gas to form a foam, and stabilizing the foam by causing the adhesive material to solidify. The relatively low melt-viscosity of the adhesive material which is used to form the foam provides desirable processing times and the ability to form foams having desired physical properties, e.g., caliper and cell structure.

Abstract: An acrylic synthetic fiber having in the transverse section thereof many openings having an indeterminate shape and a size of 0.1 to 1.6 .mu.m, wherein in the interior of the fiber, each opening forms a vein-like or straw-like void extending substantially in parallel to the longitudinal axis of the fiber and having a length of at least 60 .mu.m. This acrylic fiber is prepared by a) dissolving in a suitable solvent an acrylic polymer comprising at least 60 weight % of an acrylonitrile unit and 5 to 20 weight %, based on the weight of the acrylic polymer, of a polyalkylene glycol having a number average molecular weight of 5,000 to 50,000, b) aging the formed spinning solution for at least 4 hours, and c) extruding the spinning solution into a coagulating medium. The acrylic fiber is useful, e.g., as a frictional material comprising (a) a pulpy material made from the acrylic fiber, (b) a resin and (c) a filler.

Abstract: The invention relates to a method of producing a multi-layer, preferably two-layer, sandwich of a foamed polystyrene film with a co-extruded unfoamed film, in particular for further working into labels or shaped bodies utilizing the shrinkability of the films, in which a polystyrene resin composition, together with nitrogen as expansion agent and a pore-former, is extruded out of the nozzle of an extruder and the extruded composition is expanded prior to cooling to below the softening point.

Abstract: A process for producing a porous pipe is disclosed and includes forming an extrudable mixture comprising elastomer particles, binder component and a solid water carrier component having a composition other than the elastomer particles and the binder component and being associated with sufficient water to provide porosity to a porous pipe produced from the mixture; and extruding the extrudable mixture to conditions effective to form the porous pipe.

Abstract: A method for manufacturing an automobile trim component includes the step of coextruding a plastic unfoamed material and foamed material into a multilayer parison, which is thereafter blow molded to a desired form. After the layers are cured, the article is removed from the blow mold and sectioned into multilayer skin halves, and one skin is placed in an injection mold. The core resin, either thermoplastic or thermoset in nature, is then injected into the injection mold and onto the skin, and then compresses the resin against the skin to produce a shell comprising a resin core layer, intermediate foam layer, and decorative outer layer.

Abstract: Foamable thermoplastic resin compositions are provided having vinyl chloride polymer, a graft copolymer having a superstrate grafted to a substrate wherein the superstrate has alphamethyl styrene, unsaturated nitrile, and unsubstituted styrene therein, and the substrate is a butadiene rubber, a rubber-free copolymer having alkylmethacrylate, vinyl aromatic, and unsaturated nitrile therein, and a chemical blowing agent. The foamable thermoplastic resin composition may be coextruded with a non-foamed thermoplastic resin skin to produce a coextruded rigid foamed structure by a process of coextruding the skin and foamable thermoplastic composition. The composition and process are useful for, making coextruded rigid foam structures which are useful in rigid foam applications such as foamed pipe and foamed sheet.

Abstract: A process and apparatus for manufacturing a molding including a portion formed of hybrid of hard rubber and sponge rubber. The process includes steps of introducing the hard rubber and the sponge rubber into a conduit through a plurality of first ports and a plurality of second ports positioned between the first ports, thereby to form hybrid of the hard rubber and the sponge rubber in which a plurality of hard rubber filaments are uniformly embedded in the sponge rubber, and extruding the hybrid from a extrusion opening to form the hybrid portion. The apparatus includes a flow conduit for forming the hybrid, the flow conduit communicating with a sponge rubber feed pipe through a plurality of first ports and communicating with a hard rubber feed pipe through a plurality of second ports positioned between the first ports.

Abstract: Flexible tubular film is helically cut into a flat strip by feeding the tubular film in flattened form from a supply source to a film feeding means advancing the flat film tube at a predetermined velocity to a tube expansion zone in which the flat tube is expanded into a generally cylindrical tube and passed axially over a hollow mandrel slightly less in external diameter than the diameter of the expanded tube to be cut helically while on the mandrel into a flat strop that is removed at an angle to the mandrel axis. The tube is expanded in the zone by inflation with air fed through the mandrel in a direction countercurrent to the direction of tube movement and under a pressure sufficient to render the expanded tube stiff as it slides over the mandrel and resistant to deformation while being helically cut.

Abstract: An electrically insulated conductor including an electrically conductive element surrounded by ultramicrocellular foamed polymer insulation having a void volume greater than about 75%, wherein the transmission speed of the insulated conductor is greater than 90% of the speed of light. Such insulated conductors are useful in computer and telecommunications applications.

Abstract: A method for preparing composite foam articles by the coextrusion of at least two interdigitated layers in abutting relationship to each other, wherein at least one layer of composite article comprises at least one expanded thermoplastic resinous material. At least one physical expansion agent is incorporated into at least one of the layers under a pressure sufficient to keep the expansion agent quiescent and the individual melt streams are combined and interdigitated into a composite layered stream. The composite layered stream is expressed while the operating pressures and temperatures of individual melt streams are controlled to provide a coextrusion product having a stable foam structure.

Abstract: Volatile substances in polyphenylene ether or polyphenylene ether/polystyrene compositions are substantially reduced by extruding the resins in a single pass using a plurality of stages comprising water injection and vacuum venting.

Abstract: A method and apparatus for the preparation of multicolor, multidensity and/or multithermoplastic foam and products composed thereof. Heat-plastified foamable gels of a thermoplastic resin or resins containing blowing agents are combined and extruded simultaneously through the same orifice of a die and expanded into a foam. The color, density and/or thermoplastic resin of the secondary foamed gel or gels can form a multitude of patterns or shapes that include waves, diagonals, stripes and/or continuous coverage over the entire surface of the primary foamed gel. These patterns or shapes can be on the surface and/or within the cross-section of the primary foamed gel.

Abstract: A rubber shaped article having a finishing layer which comprisesa main body of rubber shaped article made of EPDM,a finishing layer of a PVC composition formed on the main body, andan adhesive layer formed between the main body and the finishing layer, said adhesive layer comprising 40 to 80% by weight of NBR, 20 to 40% by weight of EPDM and 0 to 35% by weight of SBR; and a process for producing said rubber shaped article.The rubber shaped article of the present invention provides internal and external automotive trims having an improved decorative design, with high productivity.

Abstract: The extrusion head has a head body which accommodates a male element and defines, in co-operation with the male element, a passage for material to be extruded. The passage extends around the male element and leads outward through an extrusion hole which is located proximate to an end of the head. A cooling element is applied at the extrusion hole and a hole is defined therein for the passage of the extruded material. The latter hole has a configuration which corresponds to the profile of the extruded element to be obtained, in order to achieve the rapid cooling of the extruded element exiting from the extrusion hole.

Abstract: The extrusion head has a body which accommodates a male element and which defines, in co-operation with the male element, a passage for the material to be extruded. The passage extends around the male element and leads outward through an extrusion hole located proximate to an end of the head. The end of the male element which is orientated in the direction of flow of the material has at least one channel through which material is delivered inside the flow of material which flows out of the extrustion hole.

Abstract: A method for removing volatile substances from polyphenylene ether (PPE) resin blends in an extruder comprising adding a second thermoplastic resin downstream from the PPE feedport and one stage of water injection followed by vacuum venting is disclosed.

Abstract: A method of producing a foamed thermoplastic plastics material wherein the plastics material is mixed with a pulverulent nucleating agent and is then fused in an extrusion device. A gaseous nucleating agent, generally nitrogen, is then injected into the fused mixture in an amount of from about 0.1% to 0.5% by weight. Thereafter, a liquid propellant is injected into the fused mixture in an amount of from 0.5% to 6.0%, preferably 0.5% to 5.0%, by weight. The mixture is then conveyed to an extrusion head and extruder whereupon foaming occurs.

Abstract: A method and apparatus for dispensing a foamable, pressurized solution of a gas and a high viscosity polymeric material in a manner which produces a foamed bead having a hollow core. Initial foaming occurs in a nozzle through which the solution is dispensed to atmosphere, at a core of the bead. Subsequent foaming of of the bead exteriorly of the core occurs outside the nozzle, and results in an extruded, foamed bead of high viscosity polymeric material having a tubular shape and particularly suitable for form-in-place gasket applications.

Abstract: A heat-shrinkable, tubular foam can be produced from a composition which comprises 100 parts by weight of an ethylene-.alpha.-olefin-nonconjugated diene copolymer, 1 to 20 parts by weight of a foaming agent, 5 to 100 parts by weight of a thermoplastic resin having a Vicat softening point of 50.degree. to 200.degree. C., and up to 10 parts by weight of a crosslinking agent, by shaping the composition into a tube, crosslinking and foaming the tube and pressurizing the tube in the interior to inflate it. This heat-shrinkable, tubular foam is best suited for jacketing pipes, hoses, and the like.