Abstract: There is provided pre-expanded particles of a propylene resin having a high expansion ratio and excellent molding adhesion without using a volatile blowing agent or increasing an expansion pressure. The pre-expanded particles of a propylene resin are prepared by the process comprising dispersing resin particles comprising a propylene resin composition, which contains 100 parts by weight of (A) a random copolymer of ethylene and propylene having an ethylene content of 1.5 to 4.5% by weight and 0.

Abstract: Disclosed herein is an molded article of foamed and expanded beads of a propylene resin, which is obtained by heating and molding the foamed beads of the propylene resin, wherein the apparent density of the molded article is 0.11 to 0.45 g/cm.sup.3, a value obtained by dividing its maximum bending strength (kgf/cm.sup.2) determined in accordance with JIS K 7221 by the apparent density (g/cm.sup.3) is at least 160 (kgf/cm.sup.2)/(g/cm.sup.3), and the average number of cells at its section is within a range of 5 to 100 cells/mm.sup.2.

Abstract: Polyolefinic foam beads which can be processed over a wide temperature range to give molded articles where a ratio of the areas of low-temperature peak and high-temperature peak in the DSC curve during the first heating has a value of not more than 3, and where the heat of fusion of the secondary crystals is greater than 10 J/g.

Abstract: Resin particles made from a resin mixture of 30 to 70 wt % of a linear low-density polyethylene I having a resin density of 0.930 to 0.935 g/cm.sup.3 and an MI of 1 g/10 minutes or higher and 70 to 30 wt % of a linear low-density polyethylene II having a resin density of 0.915 to 0.925 g/cm.sup.3 and an MI of 2 g/10 minutes or higher are impregnated under pressurization with a volatile expansion agent, and released into a low-pressure atmosphere to yield non-crosslinked linear low density polyethylene preexpanded particles, which, when subjected to expansion molding inside a mold, exhibit good moldability, and yield molded articles that have an attractive external appearance and exhibit outstanding cushioning properties.

Abstract: Impurities dissolved in a solid polymer and/or trapped in the spacial volume of the polymer can be removed quickly and efficiently in one or more relatively short pressurization/depressurization cycles, using a penetrant fluid (e.g. carbon dioxide) having at least some solubility in the polymer. Polymers with inherently slow or delayed elastic recovery at the temperature or temperatures at which the cycle is carried out (e.g. within the range of 20 to 200.degree. C.) or polymers with a high T.sub.g are the ones most efficiently treated. The penetrant is used to expand the polymer matrix, increasing its spacial volume. The pressure is then decreased rapidly, so that the impurities will migrate out of the polymer matrix before the matrix has a chance to relax or return to substantially its original volume. Each complete cycle should last seconds or minutes rather than hours.

Abstract: A continuous process for preparing bead-form expandable styrene polymers in which the styrene is prepolymerized in bulk to a conversion of 10 to 80%, the prepolymer is dispersed in liquid form in an aqueous phase in the presence of suspension stabilizers, and the polymerization of the prepolymer is completed in an aqueous suspension to a residual styrene content of less than 2000 ppm.

Abstract: A process for preparing polyolefin resin pre-expanded particles comprising imparting expandability to polyolefin resin expanded particles having a crystal structure which shows two melting points in a DSC curve and heat expanding expanded particles having expandability, in which the relation between heat expansion temperature and the amount of a fusion preventing agent being attached to the surface of the polyolefin resin expanded particles is represented by the inequality: t-T.sub.V .ltoreq.49.1C-27.0 (t is heat expansion temperature, C is the amount of the fusion preventing agent being attached to the surface of the polyolefin resin expanded particles and T.sub.V is saddle temperature between two peaks showing two respective melting points in the DSC curve), and t is within the temperature range represented by the inequality: T.sub.L -30.ltoreq.t.ltoreq.T.sub.V (T.sub.V is the same as defined above and T.sub.L is lower melting point of the two melting points).

Abstract: The invention is directed at a composite material comprising a product of a combination of materials. The combination of materials comprises an inorganic filler comprised of ceramic cenospheres, a thermoplastic polymer and a coupling agent comprised of at least one fatty acid having at least 16 carbon atoms and at least one rosin acid having at least 16 carbon atoms. The combination may further comprise an organic filler comprised of cellulosic material and wherein the thermoplastic polymer has a melt temperature of less than the char temperature of the organic filler. The invention is further directed at a process for producing the composite material comprising the step of combining the components at a temperature of greater than or equal to the melt temperature of the thermoplastic polymer. Where the components include the organic filler, the process temperature is less than the char temperature of the organic filler.

Abstract: Partially expanded polyolefin granules are post-expanded by a process comprising charging a vessel containing foamed polyolefin beads having a bulk density of from 20-450 g/l with an inert gas under a pressure of from 2-25 bar and at a temperature of from T.sub.m -150.degree. C. to T.sub.m -40.degree. C. over a period of from 1-48 h, and then continuously or discontinuously transferring the pressurized foam beads into an apparatus in which a fluidized bed is created, where the beads expand further at a temperature of from T.sub.m -75.degree. C. to T.sub.m +20.degree. C.The resultant foamed beads are suitable for producing foamed moldings.

Abstract: Post-treatment method of polyolefin resin pre-expanded particles comprising: introducing the polyolefin resin pre-expanded particles foamed by using an inflammable blowing agent into an extraction vessel filled with steam previously; feeding an additional steam into the extraction vessel; extracting the inflammable blowing agent gas from the polyolefin resin pre-expanded particles; discharging the resulting steam which contains the extracted inflammable blowing agent gas from the extraction vessel continuously or intermittently; and liquefying the steam to separate and recover the inflammable blowing agent gas. According to the post-treatment method of polyolefin resin pre-expanded particles, the inflammable blowing agent can be extracted from the pre-expanded particles in a short period of time and the extracted inflammable blowing agent can be re-used.

Abstract: An amphiphilic block copolymer including a hydrophilic internal segment and polymeric articles made therefrom.

Abstract: In a process for producing polyolefin foam particles, partially foamed particles are produced in a first stage by extrusion of a polyolefin containing solid blowing agents, and these are then further foamed in the second stage using steam.

Abstract: A continuous process for making moldable foam beads comprising a non-crosslinked or crosslinked thermoplastic polymer foam are produced by mixing a composition comprising a non-crosslinkable or crosslinkable thermoplastic polymer or a thermoplastic polymer with a crosslinking agent, additives to achieve specific properties, a blowing agent, extruding the admixture under pressure, crosslinking, when applicable, the admixture under pressure, modulating the admixtures temperature to achieve the desired foaming properties, and then expanding the admixture in a zone of lower pressure to form a foam bead that can be molded.

Abstract: Prefoamed polyolefin beads, produced by extrusion followed by granulation, have a crystal structure with a double peak.

Abstract: An expanded, memory molded, increased density, highly impact-resistant polystyrene construct, and method of making the construct. The construct is formed by molding pre-expanded non-equilibrated polystyrene beads to a first volume, cooling rapidly, and then compression molding to a final, smaller volume. The resultant constructs have increased density, and high impact strength without increase in embrittlement. Also, the construct has "memory" in the sense that it returns substantially to its original shape after impact.

Abstract: Heat temperature at the expansion molding of a finished expanded article is decreased by lowering the melting peak temperature of the pre-expanded particles of a polypropylene resin. Comprising the polypropylene resin and a .beta.-crystalline-nucleating agent, the percentage of the .beta.-form in the whole crystalline region is 5 to 100 parts by weight.

Abstract: An expandable styrene resin bead containing voids therein, wherein the number of the voids present in the area from the surface of the bead to a depth of 0.1 mm along the radial direction is not more than 100 per mm.sup.2 as counted on a cross section passing through approximately the center of the bead. A process for producing expandable styrene resin beads by suspension polymerization is also disclosed in which a styrene monomer is suspended in an aqueous medium in the presence of an initiator and a suspending agent, and a blowing agent is incorporated into polymer beads produced, wherein an alkali metal salt or ammonium salt of persulfuric acid is added to the reaction system in an amount of 0.5 to 30 ppm based on the aqueous medium while the degree of conversion of said monomer is in the range of from 0 to 30%, and an electrolyte is added to the reaction system in a concentration of 0.02 to 5.0 mol/l based on the aqueous medium when the degree of conversion is 30% or higher.

Abstract: A strippable pressure-sensitive adhesive and an adhesive material using the same are disclosed, adhesive comprising a highly elastic base polymer whose dynamic modulus of elasticity is in the range of from 250,000 to 10,000,000 dyne/cm.sup.2 at a temperature between ambient temperature and 150.degree. C. with a small rate of change with temperature, having incorporated therein a blowing agent, which adhesive reduces or loses its adhesiveness on expansion or blowing of blowing agent. The adhesive and adhesive material are easily re-applied, is capable of satisfactorily following the shape of an adherent during forming of the adherent, reduces its adhesiveness on heating, and is applicable to various adherents with excellent workability.

Abstract: A continuous process for making moldable foam beads comprising a non-crosslinked or crosslinked thermoplastic polymer foam are produced by mixing a composition comprising a non-crosslinkable or crosslinkable thermoplastic polymer or a thermoplastic polymer with a crosslinking agent, additives to achieve specific properties, a blowing agent, extruding the admixture under pressure, crosslinking, when applicable, the admixture under pressure, modulating the admixtures temperature to achieve the desired foaming properties, and then expanding the admixture in a zone of lower pressure to form a foam bead that can be molded.

Abstract: The present invention relates to a process for preparing pre-expanded articles of a polyolefin resin wherein a blowing agent is incorporated into the polyolefin resin in an amount of 45 to 90 parts by volume with respect to 100 parts by volume of the resin and the pre-expansion is carried out at a temperature in the range of from Tm -35.degree. C. to Tm -20.degree. C., or a second external pressured gas which facilitate the impregnation efficiency of the blowing agent is further introduced in an amount of expressing an additional pressure more than 10 kg/cm.sup.2 with the blowing agent. Also, the present invention relates to pre-expanded articles of a polyolefin resin produced by the above process.

Abstract: A method and apparatus for producing a lightly crosslinked polyolefin foam and articles made therefrom is disclosed. According to the method, a polyolefin resin is lightly crosslinked, mixed with a blowing agent, forwarded as a molten gel admixture through an extruder, cooled, and expelled from a die into a zone of lower pressure, e.g., the atmosphere or a controlled pressure zone, to produce a uniform fine celled expanded shape.

Abstract: Microsphere beads are mixed with a surface barrier liquid or mixture of such a liquid with a solid effective to prevent agglomeration and surface bonding of the microspheres; by the control of the application of heat and balancing temperature and active mixing, removal of water from the microspheres is achieved.The surface barrier liquid or mixture of such a liquid with a solid in the present invention is any one of a wide diversity of materials which meet the requirements of the intended function, i.e., to prevent the agglomeration of the microspheres during the process. Suitable materials include, by way of example, plasticizers, diluents, extenders, monomers and oligomers, and the like.

Abstract: The production of approximately spherical polyolefin foam particles having a coarse cell structure and a narrow cell size distribution by dispersion foaming is achieved by a process in which the reactor contents, which essentially comprise polyolefin particles, a liquid dispersion medium and, if desired, a volatile blowing agent, are first treated at a first temperature above the crystallite melting point T.sub.m of the polyolefin, and subsequently passed through a cooling device, in which the dispersion is brought to a second, lower temperature, and the polymer particles are then foamed at this temperature. The foamed particles can be converted into moldings by known methods.

Abstract: A process for producing expandable particles of a melt compounded blend of polyphenylene ether resin and polyolefin resin. A melt compounded blend of polyphenylene ether resin and polyolefin resin, a blowing agent and water are mixed in a pressure vessel to form a dispersion; the dispersion is heated in the sealed pressure vessel to impregnate the blowing agent in the melt compounded blend of resin particles; the dispersion is then cooled in the sealed pressure vessel; and a cooled blowing agent-impregnated, melt compounded blend of resin particles is removed from the reactor. A preferred blowing agent is Freon.RTM. 11. The particles are pre-expanded by heating, and the pre-expanded particles can be foamed in a conventional mold when heat is applied thereto. A resin molding composition comprising a melt compounded blend of heat-pre-expanded, low density, resilient polyphenylene ether resin and polyolefin resin particles having about 95.0 weight percent to about 5.

Abstract: There are provided polypropylene resin expanded particles which have a uniform bubble size, can be molded with an exceptionally low steam pressure, and can produce an expanded molded product having a good surface appearance and an excellent energy absorption property. The present particles are polypropylene resin expanded particles containing as a base resin an isotactic polypropylene resin polymerized in the presence of a metallocene polymerization catalyst.

Abstract: A pre-expanded particle of a polyethylene resin based on a non-crosslinked linear very low density polyethylene having a density of 0.88 to 0.915 g/cm.sup.3 and a melt index of 0.1 to 20 g/10 min. which can be used to produce a cellular molded article having superior flexibility, excellent bonding together of the particles, and both large tensile strength and large elongation at break.

Abstract: Disclosed herein is a method of producing foamed particles of an ethylene-based resin, which have a high expansion ratio and are free from the formation of fine cells, by dispersing particles of the uncrosslinked ethylene-based resin, which are obtained using, as a base resin, an ethylene/.alpha.-olefin copolymer containing, as a comonomer component, 1.0-10 wt. % of an .alpha.-olefin having 4-10 carbon atoms, in a dispersion medium in the presence of a foaming agent in a closed vessel, heating the resultant dispersion to impregnate the resin particles with the foaming agent, and then releasing the resin particles into a region of a pressure lower than the internal pressure of the vessel at a foaming temperature not lower than the softening temperature of the resin particles, thereby expanding the resin particles.

Abstract: Foamed polyolefin particles are prepared by dispersion foaming of components consisting essentially of polyolefin particles, a liquid dispersing agent and optionally a volatile blowing agent in a reaction system consisting essentially of a reactor equipped with a stirrer containing said components and a discharge jet, comprising the step of:gassing the components of the reactor by injecting an inert gas into the dispersion below the surface of the liquid in the reactor;and simultaneouslydischarging a three phase mixture of liquid dispersing agent, polymer particles and gas through said jet.

Abstract: Disclosed is a process for making closed-cell, alkenyl aromatic polymer foam packing bodies. An alkenyl aromatic polymer material is heated to form a melt polymer material. The melt polymer material comprises greater than 50 percent by weight alkenyl aromatic monomeric units. A blowing agent is incorporated into the melt polymer material at an elevated pressure to form a foamable gel. The blowing agent has about 20 weight percent or more based upon the total weight of the first blowing agent selected from the group consisting of carbon dioxide and ethane. The foamable gel is extruded through a die to form a foam strand. The foam strand is pelletized to form a plurality of foam bodies. The bodies are further expanded by exposing them one or more times to heated air or steam. Preferably, the bodies are allowed to age for a preselected period of time after pelletizing and between subsequent expansions.

Abstract: Low molecular weight, polyoxyalkylene polyamine reacts with carbonyl compound making polyamine adduct used as chain extender in preparing tack-free, smooth polyurea elastomers, useful in solventless spray coatings.

Abstract: A lightweight silicone ear molding putty composition is disclosed for chronic ear patients and myringotomy children to protect ears which includes a mixture comprising of silicone hydroxy functional fluid, crosslinker, and tints as well as a number of additives for adjusting the properties of the mixture and further including an admixture of hollow thermoplastic microspheres containing microcrystalline silica embedded onto the sphere combined with a 5 micron diatomic functional filler. The final composition cures in five minutes to a floating ear plug. Utilizing a mixture of thermoplastic microspheres of 10 to 80 microns and silicone hydroxy fluid ranging from 18,000 to 20,000 centipoise said composition is cured at room temperature, hand mixed, moldable, and syringed into the ear to make an ear plug or mold which has superior properties over prior art ear plugs.

Abstract: Microsphere wet cake is mixed with a surface barrier coating effective to prevent agglomeration and surface bonding of the microspheres, and removing water by drying with continuous mixing at high shear. In a subsequent step, by the control of the application of heat and balancing temperature and low shear mixing, it is possible to also control expansion of the microspheres.The surface barrier coating in the present invention is any one of a wide diversity of materials which meet the requirements of the intended function, i.e., to prevent the agglomeration of the microspheres during the process. Suitable materials include, by way of example, dry inorganic pigments or filler materials, and the like, and related organic materials.

Abstract: A polystyrene polymer as well as an expandable polystyrene formulation comprises a polystyrene polymer having a particular molecular weight distribution. The polymer itself exhibits a polydispersity of from about 1 to less tha 2.0, a weight average molecular weight of greater than about 200,000 to about 300,000, and an M.sub.z :M.sub.n of from about 2 to less than about 3.0. Furthermore, the polystyrene polymer is branched to from 0 to less than 5 weight percent.The expandable polystyrene formulation comprises a polystyrene polymer exhibiting a polydispersity of from about 1.0 to less than 2.5, a weight average molecular weight of from greater than about 180,000 to about 300,000, an M.sub.z :M.sub.n of from about 2 to about 4.5. The polystyrene polymer is present in an amount of from about 94.5 weight percent to about 98 weight percent, based on the total weight of the formulation, and the polystyrene polymer is branched to from 0 to less than 5 weight percent.

Abstract: A method for making low density (0.8-1.1 lb./cu.ft.) expanded polymeric products uses blowing agent in an amount of any from 2 to 4.4 weight percent and aging periods of from 1 to 80 hours after each expansion step. The process uses 2 to 5 expansion steps and a polymer having a particular polydispersity, weight average molecular weight and M.sub.z :M.sub.n, this polymer having a greater expandability than conventional polymers. The process requires only about half of the amount of blowing currently being used in commercially viable processes for making expanded polystyrene products. The process can be used with or without a molding step.

Abstract: A polystyrene polymer as well as an expandable polystyrene formulation comprises a polystyrene polymer having a particular molecular weight distribution. The polymer itself exhibits a polydispersity of from about 1 to less than 2.0, a weight average molecular weight of greater than about 200,000 to about 300,000, and an M.sub.z :M.sub.n of from about 2 to less than about 3.0. Furthermore, the polystyrene polymer is branched to from 0 to less than 5 weight percent.The expandable polystyrene formulation comprises a polystyrene polymer exhibiting a polydispersity of from about 1.0 to less than 2.5, a weight average molecular weight of from greater than about 180,000 to about 300,000, an M.sub.z :M.sub.n of from about 2 to about 4.5. The polystyrene polymer is present in an amount of from about 94.5 weight percent to about 98 weight percent, based on the total weight of the formulation, and the polystyrene polymer is branched to from 0 to less than 5 weight percent.

Abstract: A method for making low density (0.8-1.1 lb/cu.ft.) expanded polymeric products uses blowing agent in an amount of only from 2 to 4.4 weight percent. The process uses 2 to 5 expansion steps together with a polymer having a particular polydispersity, weight average molecular weight and M.sub.z :M.sub.n, this polymer having a greater expandability than conventional polymers. The process requires only about half of the amount of blowing agent currently being used in commercially viable processes for making expanded polystyrene products. The process can be used with or without a molding step.

Abstract: A method for making low density (0.8-1.1 lb/cu.ft.) expanded polymeric products uses blowing agent in an amount of only from 2 to 4.4 weight percent and aging periods of from 1 to 80 hours after each expansion step. The process uses 2 to 5 expansion steps and a polymer having a particular polydispersity, weight average molecular weight and M.sub.z :M.sub.n, this polymer having a greater expandability than conventional polymers. The process requires only about half of the amount of blowing agent currently being used in commerically viable processes for making expanded polystyrene products. The process can be used with or without a molding step.

Abstract: A method for making low density (0.8-1.1 lb/cu. ft.) expanded polymeric products uses blowing agent in an amount of only from 2 to 4.4 weight percent. The process uses 2 to 5 expansion steps together with a polymer having a particular polydispersity, weight average molecular weight and M.sub.z :M.sub.n, this polymer having a greater expandability than conventional polymers. The process requires only about half of the amount of blowing agent currently being used in commercially viable processes for making expanded polystyrene products. The process can be used with or without a molding step.

Abstract: This invention relates to an expandable tape for use in making cables. The expandable tape comprises a carrier material carrying thermally expanding microcapsules therein or thereon. The invention also relates to the use of the tape in the manufacture of cables, and to the cables incorporating such tape.

Abstract: A method for making low density (0.8-2 lb/cu.ft.) expanded polymeric products uses blowing agent in an amount of only from 2 to 4.4 weight percent, the process emitting blowing agent during processing in an amount of from only about 0.3 to about 2.5 weight percent. The process uses 2 to 5 expansion steps together with a polymer having a particular polydispersity, weight average molecular weight and M.sub.z :M.sub.n, this polymer having a greater expandability than conventional polymers. The process requires only about half of the amount of blowing agent currently being used in commerically viable processes for making expanded polystyrene products. The process can be used with or without a molding step.

Abstract: Novel foams having a density of from 0.01 to 0.1 g/cm.sup.3, based on a copolymer comprising ethylene, propylene and a C.sub.4 - to C.sub.8 -.alpha.-olefin, and having a torsion modulus of from 100 to 800 N/mm.sup.2 have high tensile, compressive and flexural strengths and at the same time high elongation at break.

Abstract: A process for the production of expanded resin particles is disclosed, wherein an aqueous dispersion containing expandable particles of a polyolefin resin is discharged at a temperature higher than the softening point of the resin from a high pressure condition to a low pressure condition to expand the expandable particles and wherein the expandable particles contain fine particles of an inorganic material coated with an agent selected from isopropyltriisostearic titanate, tetraoctadecyl titanate, acetoalkoxyaluminum diisopropylates, stearic acid, methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, phenyltriethoxysilane and vinyltriethoxysilane.

Abstract: A process for making high-purity foam moldings without the use of organic blowing agents involves the use of inorganic gases such as carbon dioxide, nitrogen, air and other pneumatogens.The process involves the simultaneous impregnation and purification of the polymers with or without foaming. If foaming is not done in the extractor, the polymeric particles can be foamed in pre-expanders or expanded and molded in downstream equipment.

Abstract: Foam particles of propylene polymers which have shrunk from 40 to 95% of their original volume and have a bulk density of from 10 to 30 g/1 can be expanded if they are treated with air or nitrogen under superatmospheric pressure, subsequently decompressed. If desired post-foamed by heating and, after aging, re-treated with air or nitrogen under superatmospheric pressure, subsequently decompressed and aged under atmospheric pressure until the pressure in the cells has dissipated.

Abstract: The evaporative casting of molten metals has been shown to produce casting having smooth surfaces with significantly less sign of carbon deposits thereon by using a polystyrene containing a high temperature peroxide, tert-butyl cumyl peroxide.

Abstract: Moldable shrunken foam beads comprising a foamable thermoplastic polymer, preferably a silane-crosslinked polyolefin foam, are produced by mixing a composition comprising a silane-modified polyolefin (such as a silane-grafted polyethylene) and a silanol condensation catalyst in an extruder to produce a melt, then projecting a blowing agent into the melt at a rate effective to produce a desired foam density in the extrudate; extruding and cutting the melt to form foam beads; allowing the beads to shrink; and exposing the foam beads to moisture to produce silane crosslinking of the polyolefin foam. In certain other embodiments the crosslinking of the thermoplastic polymer can be omitted, and/or shrinkage of the beads produced by vacuum treatment.

Abstract: The present invention provides polypropylene resin pre-expanded beads formed by shrinking polypropylene resin pre-expanded beads originally having a bulk density of not higher than 0.0930 g/cc to give them a bulk volume ratio of 10-75% at normal temperature and normal pressure, a manufacturing method thereof and an expansion-molding method with the aforementioned pre-expanded beads. According to this invention, it is possible to greatly reduce storing and transporting costs per unit weight of pre-expanded beads.

Abstract: A method of forming pre-foamed beads of a polyethylene-base resin are disclosed. The polyethylene-base resin has been obtained by crosslinking a starting polyethylene-base resin having a density greater than 0.940 g/cm.sup.3 and the pre-foamed beads have a crosslinking degree of 10-45% gel content. The pre-foamed beads can provide a molded articles having excellent rigidity and dimensional accuracy and showing superb dimensional stability under heat.

Abstract: Enhanced hiding power for opacifiers in paints, inks, and other coatings is provided by employing the opacifiers, such as TiO.sub.2, ZnO, talc, CaCo.sub.3, and the like, adhered to or embedded in the surface of thermoplastic microspheres. The composite opacifier-microsphere material is readily formed with a preselected specific gravity, so that there is little tendency for the material to separate. In addition, the composite behaves in the coating as a opacifier-air interface, having a very high difference in refractive indices, and exceptional hiding power. The high volume to weight ratio of the composite affords very attractive economic advantages, effectively reducing the weight proportion of opacifiers required in the formulations, and other related advantages.

Abstract: The process of enabling foam moldings to expand further than otherwise by impregnating the expanded sheet with inorganic gases such as carbon dioxide, nitrogen, air and other pneumatogens prior to reheating to effect expansion.