Abstract: Cushions for dynamic impact applications include anisotropic cellular polymers made in an extrusion, expanded bead or reactive foaming process. The anisotropic behavior represented by CE/CT, CV/CT and CH/CT, wherein CE, CV and CH represent the compressive strength of the cellular polymer in each of three orthogonal directions E, V and H, respectively, as measured by compressing a 25-50 mm thick sample of the cellular polymer at a strain rate of 0.08 s?1 to 25% strain, CT represents the sum of CE, CV and CH, and at least one of CE/CT, CV/CT and CH/CT has a value of at least 0.40, up to about 0.80. The cellular polymer also preferably has density of 1.75 to 2.35 pounds/cubic foot and a compressive stress in the direction of maximum compressive strength of 290-600 kPa at 25% strain when used for headliner countermeasure applications. The cushions are useful in automotive applications such as automotive headliners, door panels, knee bolsters, pillars, headrests, seat backs, load floors or instrument panels.

Abstract: A nanoporous material is provided. The pores of the nanoporous material are formed between nanoparticles that have a polymeric surface layer. The nanoporous material is produced by (a) suspending the nanoparticles in a medium material, wherein the nanoparticles are phase separated from the medium material, (b) heating the suspension to a temperature above the melting point of the nanoparticle surface layer, and (c) cooling the suspension. Alternatively, the nanoporous material may be produced by dissolving nanoparticles having a polymeric surface layer in a solvent, and then adding a medium material that causes the nanoparticles to phase separate from the solution.

Abstract: Polymer foam containing styrene-acrylonitrile and containing one or more infrared attenuating agents achieves surprisingly high dimensional integrity at elevated temperatures.

Abstract: The present invention relates to a porous resin bead containing a first aromatic monovinyl compound-divinyl compound-(meth)acrylonitrile-second aromatic monovinyl compound copolymer, in which the second aromatic monovinyl compound contains a group capable of binding with a carboxyl group by dehydration condensation reaction, and in which the porous resin bead has a dry volume of from 2 to 3 ml/g.

Abstract: Prepare a polymeric foam from a foamable polymer composition containing a thermoplastic polymer composition and a blowing agent wherein 75 percent or more by weight of all non-halogenated polymers in the foamable polymer composition is a styrene-acrylonitrile copolymer composition having a polymerized acrylonitrile content distribution with a positive skew in a copolymerized AN content distribution and a positive percent difference between the mean and the median copolymerized AN content distribution.

Abstract: Process for improving the insulating capacity of expanded vinyl aromatic which comprises: 1) preparing beads of expandable vinyl aromatic polymers containing 1-10% by weight, calculated with respect to the polymer, of an expanding agent englobed in the polymeric matrix and 0.001-25% by weight, calculated with respect to the polymer (a), of an athermanous additive comprising carbon black homogeneously distributed in the polymeric matrix; 2) treating the surface of the beads, before deposition of the coating, with a liquid lubricating agent; and 3) thermally treating the beads with hot air at a temperature ranging from 30 to 60° C.

Abstract: A hard foam formed from a carboxylic acid ester-based polymer having a ring structure, the hard foam being obtained by heating the carboxylic acid ester-based polymer having a ring structure to generate a gaseous organic acid from the carboxylic acid ester-based polymer, and foaming the heated carboxylic acid ester-based polymer with the gaseous organic acid, and a method for producing the same. The hard foam can be used as various heat insulating materials, various vibration isolators, various acoustic materials, various soundproof materials and the like. Therefore, the hard foam is expected to be used for automobile component materials, materials for airplanes, materials for the space field, materials for industries, materials for medical assistance, and the like.

Abstract: A shape memory polymer network may include at least one polymer, a plurality of proton accepting heterocyclic groups, a plurality of proton donating groups, and a plurality of cross-link moieties. At least one of the proton accepting heterocyclic groups and the proton donating groups is attached to the at least one polymer. The network may include an original shape at zero stress, and may include a deformed shape upon subjection to a stress. The network changes from the deformed shape to the original shape upon exposure to an external stimulus.

Abstract: Methylated polystyrene having pendant N-halamine and N-halamine precursor groups. Biocidal particles have been prepared by reacting highly crosslinked methylated polystyrene beads as starting materials with various N-halamine precursor compounds. The resulting polymer beads are halogenated with chlorine or bromine. The porous beads will be useful in disinfection applications as well as for sanitization and controlling noxious odor when mixed with absorbent materials in items such as disposable diapers, infant swimwear, incontinence pads, bandages, sanitary napkins, pantiliners, mattress covers, shoe inserts, sponges, animal litter, carpets, and fabrics.

Abstract: The invention relates to e new environmentally friendly process in which cellular foamed polymer particles selected from the group consisting of cross-linked PVC rigid foam, polyurethane, polyester, polyether and polystyrene are recycled and reused in new extruded acoustics products together with other plastic components.

Abstract: The present invention provides porous resin beads containing an aromatic monovinyl compound-divinyl compound-(meth)acrylamide derivative copolymer. Preferably, the copolymer further contains as a structural unit a second aromatic monovinyl compound having a functional group capable of binding to a carboxyl group by a dehydrating condensation reaction.

Abstract: Expandable vinylaromatic polymers which comprise: a) a matrix obtained by polymerizing 50-100% by weight of one or more vinylaromatic monomers and 0-50% by weight of a copolymerizable monomer; b) 1-10% by weight, calculated with respect to the polymer (a) of an expanding agent englobed in the polymeric matrix; c) 0.01-20% by weight, calculated with respect to the polymer (a) of carbon black distributed in the polymeric matrix having an average diameter ranging from 30 to 2000 nm, a surface area ranging from 5 to 40 m2/g, a sulfur content ranging from 0.1 to 2000 ppm and an ash content ranging from 0.001 to 1%.

Abstract: A monomer having a pair of hydroxy groups held in a fixed relationship (e.g. a dihydroxybenzene) is diesterified with a compound having a polymerisable group, e.g. to form a diacrylate. After polymerisation with a crosslinker, the polymer is hydrolysed. The dihydroxy-monomer is removed, leaving a polymer with pair of carboxyl groups held in spatial relationships determined by the dihydroxy monomer. Thus a range of subtly different polymers can be prepared by using different dihydroxy-monomer templates. The polymers are desirably swellable. They can be used as selective binding materials, e.g. in chromatography or analysis.

Abstract: Disclosed herein is a method of preparing a fused aerogel-polymer composite in which aerogel and an organic polymer is mixed in a dry state to adsorb polymer particles on the surface of the aerogel and are then subjected to thermal treatment, thus forming a polymer coating on the aerogel. The fused aerogel-polymer composite can be used for thermal insulation in a variety of applications. The fused aerogel-polymer composite exhibits high thermal insulation properties and superior physical strength and processability while still maintaining the properties of an aerogel that does not have a polymer coated on its surface.

Abstract: The present invention relates to a process for preparation of copolymers A) comprising A1) one or more vinylaromatic monomers, A2) one or more vinyl cyanides, and A3) one or more dicarboxylic anhydrides via bulk polymerization or via solution polymerization, an important feature of the invention being that the polymerization is carried out in the presence of from 0.01 to 0.5% by weight of water, based on the total weight of the polymerization mixture. The present invention further relates to the copolymers A), to thermoplastic molding compositions comprising the copolymers A), to the use of the copolymers A) and of the thermoplastic molding compositions, and also to the moldings, foils, fibers, or foams obtainable from the copolymers A) or from the thermoplastic molding compositions.

Abstract: A composition including an effective amount of trans-1,3,3,3-tetrafluoropropene component combined with an effective amount of an alcohol selected from the group of methanol, ethanol, propanol, isopropanol, tert-butanol, isobutanol, 2-ethyl hexanol and any combination thereof, where the composition has azeotropic properties.

Abstract: A “high internal phase polymeric emulsion” (“HIPPE”) composition is described which comprises an emulsion of a discrete phase (component A) and a continuous phase (component B), wherein the volume fraction of the discrete phase is the majority fraction (on a volume basis) of the total volume of the emulsion. A compatibilizer, component C, is used to lower the interfacial tension between the phases containing components A and B. A process is described for creating such HIPPE composition in which the A component is a colloidal polymer particle.

Abstract: Disclosed are novel compositions for the preparation of void-containing articles comprising a polymer matrix and a voiding agent The voiding agent comprises at least one first polymer and at least one second polymer, which are selected on the basis of physical properties such as glass transition temperature, tensile modulus, melting point, surface tension, and melt viscosity. Shaped articles such as sheet, film, bottles, tubes, labels, and sleeves may prepared from these compositions. Also disclosed are polyester shrink films prepared using a voiding agent comprising a novel blend of cellulosic and olefinic polymers. The resulting shrink films have better opacity, lower density, reduced shrink force, and improved printability as compared with most standard voiding agents. The films are useful for sleeve label and other shrink film applications and their lower density allows them to be readily separated from soft drink bottles, food containers and the like during recycling operations.

Abstract: A polymeric composition to be used in producing low density foam in which the polymeric composition comprises high density polyethylene, alkenyl aromatic polymer and a linear low density polyethylene. The polymeric resins may be prime virgin resin, offgrade virgin resin, recycled resin from a post industrial source, recycled resin from a post consumer source, or blends thereof Inventive compositions for producing polymeric foam are characterized by Dynamic Mechanical Spectroscopy to have a complex viscosity (?*) in the range of 6.0×104 to 2.5×105 poise and a loss tangent (tan ?) in the range of 0.7 to 2.1 at 190° C. and a power-law relation between tan ? and ?* where the exponent is within the range between ?0.70 and ?0.30 for the temperature range of 190° to 230° C.

Abstract: The present invention provides, as a resin bead which can be developed for use completely different from the use of conventional polystyrene resin beads, a porous resin bead made from a styrene-hydroxystyrene-divinylbenzene copolymer, which contain a hydroxyl group in an amount of 10–1000 ?mol/g, and further, a production method of a porous resin bead made from a styrene-hydroxystyrene-divinylbenzene copolymer, which contains suspension copolymerization of a styrene monomer, an acyloxystyrene monomer and a divinylbenzene monomer using an organic solvent (containing at least hydrocarbon and alcohol) and water, followed by hydrolysis reaction.

Abstract: A production method of a porous resin or an intermediate therefor, which comprises a step of producing a styrene-acyloxystyrene-divinylbenzene copolymer comprising suspension copolymerization of a styrene monomer, an acyloxystyrene monomer and a divinylbenzene monomer using an organic solvent and water, and a step of converting the styrene-acyloxystyrene-divinylbenzene copolymer to a styrene-hydroxystyrene-divinylbenzene copolymer, wherein a chain transfer agent is added to the suspension copolymerization system.

Abstract: A vinyl monomer of the structure R—B—Ar(—CH?CH2)n (1) in which Ar is an aromatic ring (arylene group); n is an integer >0, in particular one or two; B is a bridge structure; R is a (C2-30)-hydrocarbon group carrying two or more protected or unprotected hydroxy groups. The monomer is characterized in that B comprises a chain of atoms linking R to Ar and consisting of 1–10 atoms selected from carbons and the heteroatoms ether oxygen, thioether sulphur or amino nitrogen, with the proviso that the terminal atom in B which is attached to R is one of the heteroatoms. A method for producing a polymer support matrix in which the vinylmonomer is one of the monomeric units. The support matrix as such is also claimed. The preferred method for producing the support matrices involves suspension polymerisation, the preferred form of matrix is beads.

Abstract: It has been discovered that improved polystyrene products may be obtained by polymerizing styrene in the presence of p-t-butyl styrene (TBS) and optionally at least one di-olefinic substituted aromatic compound, such as isopro-penyl styrene, sec-butenyl styrene, m-isobutenyl styrene, p-diisopropenyl benzene, diallyl benzene, and/or diallyl phthalate. The resulting copolymers have a higher glass transition temperature (Tg), a higher molecular weight distribution (MWD), a higher Mz, and a lower melt flow index (MFI) as compared with a polymerized product made by an otherwise identical method except that TBS and/or the di-olefinic substituted aromatic compound are not used. These copoly-mers are also more highly branched as compared with a polymerized product made by an otherwise identical method in the absence of TBS and/or a di-olefinic substituted aromatic compound.

Abstract: Low density polymeric beads made by polymerizing monomeric building blocks into large crosslinked polymer molecules in porous, spherical bead form by droplet or suspension polymerization in the presence of a porogen.

Abstract: A high internal phase emulsion composition comprising: a) at least three components; b) component A is a polymer, monomer or mixture thereof; c) component B is a polymer; d) component C is a compatiblizer; e) substantially no voids; and wherein the volume fraction of component A represents at least about 80% by volume of the total volume of components A, B and C; and wherein the volume fraction of component B represents less than about 20% by volume of the total volume of components A, B and C; and wherein at least two phases are formed, a phase containing a majority of component A is discrete and a phase containing a majority of component B is continuous.

Abstract: This invention relates to latent foamable compositions for use in or as adhesives, sealants and/or coatings. The compositions include a curable component or a thermoplastic component, together with a latent foaming agent. In curable versions of the inventive compositions, a cure initiator or catalyst may also be included.

Abstract: An organic porous material having a continuous pore structure, which comprises interconnected macropores and mesopores with a radius of 0.01 to 100 ?m in the walls of the macropores, having a total pore volume of 1 to 50 ml/g and having pore distribution curve characteristics wherein the value obtained by dividing the half-width of the pore distribution curve at the main peak by the radius at the main peak is 0.5 or less. The organic porous material is useful as an adsorbent having high physical strength and excelling in adsorption amount and adsorption speed, an ion exchanger excelling in durability against swelling and shrinkage, and a filler for chromatography exhibiting high separation capability.

Abstract: This invention relates generally to water resistant peelable protective and decorative clear or pigmented coating compositions and, more specifically, to aqueous and solvent based, polymeric coating compositions which form a protective and/or decorative coating and is removably adheres to a variety of substrates, including automotive paints, metals, glass, vinyl, plastics, concrete, natural and synthetic elastomers, and ceramics. The coatings can be either a flat film on the substrate, or a three-dimensional expandable foamy coating, and can be readily peeled off from the substrate as a whole piece. The coatings may be formulated for temporary or long-term protection depending upon the application. The peelable coatings can be applied as a paint, paste, film, or expandable foam cord whereby the expansion of the foam can be controlled by the formulation and applicator.

Abstract: Prepare a multimodal thermoplastic polymer foam having a distribution of large and small cells in a substantial absence of water by using a blowing agent stabilizer. Multimodal foams of the present invention have blowing agent stabilizer predominantly located proximate to large cells. The resulting multimodal foams have particular utility as thermal insulating materials.

Abstract: The present invention is an ABS foam composition. The composition is comprised of ABS, a foam modifier, and a blowing agent. The composition may be formed into a variety of shapes and products using many different processing techniques, e.g., extrusion and molding.

Abstract: This invention relates generally to water resistant peelable protective and decorative clear or pigmented foam coating compositions and, more specifically, to aqueous and solvent based, polymeric coating compositions which form a protective and/or decorative coating and is removably adheres to a variety of substrates, including automotive paints, metals, glass, vinyl, plastics, concrete, natural and synthetic elastomers, and ceramics. The coatings present a three-dimensional expandable foamy coating, and can be readily peeled off from the substrate as a whole piece. The coatings may be formulated for temporary or long-term protection depending upon the application. The peelable coatings can be applied as a paint, paste, film, or expandable foam cord whereby the expansion of the foam can be controlled by the formulation and applicator.

Abstract: Disclosed is substantially spherical porous beads of an aromatic polyether ketone resin, which have an average particle diameter of 50 to 5,000 &mgr;m and a porosity of 40 to 99%. Also disclosed is a method for producing porous beads, which comprises: mixing, while heating, an aromatic polyether ketone resin with a sol vent capable of dissolving the resin to thereby obtain a resin solution; dispersing the resin solution in a liquid dispersion medium which is incapable of dissolving the resin and is non-miscible with the solvent, to thereby obtain a dispersion having the resin solution dispersed therein in the form of globules; cooling the dispersion while maintaining the dispersed form of the resin solution in the liquid dispersion medium, to thereby solidify the resin in the resin solution; and separating the solidified resin from a mixture of the solvent and the liquid dispersion medium, thereby obtaining substantially spherical porous beads of the aromatic polyether ketone resin.

Abstract: Disclosed are organo polysilica dielectric materials having low dielectric constants useful in electronic component manufacture are disclosed along with methods of preparing the porous organo polysilica dielectric materials. Also disclosed are methods of forming electronic devices containing such porous organo polysilica dielectric materials without the use of antireflective coatings.

Abstract: The invention relates to antimicrobial foam materials with amino alcohols, their preparation, and their use.

Abstract: A polyurethane foam which is obtained by reacting an addition-polymerizable active hydrogen component comprising a compound having a group containing active hydrogen and an addition-polymerizable functional group or comprising both this compound and a compound containing at least 2.5 groups (on the average) containing active hydrogen and not containing addition-polymerizable functional groups with an organic polyisocyanate in the presence or absence of at least one auxiliary selected from the group consisting of foaming agents and additives to polymerize the addition-polymerizable functional group and simultaneously form a polyurethane, and which has a structure in which the chains formed by the addition polymerization have been cross-linked to the polyurethane chains. The polyurethane foam is useful as a rigid polyurethane foam excellent in hardness, dimensional stability, etc. and usable as a heat insulator, shock-absorbing material, synthetic wood, etc.

Abstract: The melt of polyvinyl aromatic polymers comprising from 10 to 45 weight % of star branched polymer prepared using a combination of thermal and tetra functional peroxide initiation has an improved melt strength permitting better foam formation for extrusion foam blown with conventional blowing agents and inert gases including CO2.

Abstract: Porous dielectric materials having low dielectric constants useful in electronic component manufacture are disclosed along with methods of preparing the porous dielectric materials. Also disclosed are methods of forming integrated circuits containing such porous dielectric materials.

Abstract: This invention provides a thermoplastic polymer foam having a density of up to 800 kg/m3. The foam is made from a hydrogenated vinyl aromatic polymer that contains pendant cycloaliphatic groups. This polymer is conveniently made by hydrogenating a poly(vinyl aromatic) polymer such as polystyrene or a polystyrene-butadiene block copolymer. A suitable blowing agent is a mixture comprising (a) one or more fluorine-containing carbon compounds and (b) carbon dioxide, nitrogen, an alcohol having from 1 to 4 carbon atoms, a linear or cyclic hydrocarbon having from 1 to 6 carbon atoms, a ketone, an alkyl ether, an alkyl halide, water or a mixture thereof.

Abstract: The melt of polyvinyl aromatic polymers comprising from 10 to 45 weight % of star branched polymer prepared using a combination of thermal and tetra functional peroxide initiation has an improved melt strength permitting better foam formation for extrusion foam blown with conventional blowing agents and inert gases including CO2.

Abstract: Particles of a copolymer of a vinyl arene and a copolymerizable compound containing a polar moiety and a vinyl moiety containing water may be prepared by forming a mixture of monomers and small amounts of water and polymerizing under agitation to 20 to 70% conversion and then suspending the mass in water and finishing the polymerization. The resulting polymer beads contain finely dispersed water which is useful as an environmentally acceptable blowing agent.

Abstract: The melt of polyvinyl aromatic polymers comprising from 10 to 45 weight % of star branched polymer prepared using a combination of thermal and tetra functional peroxide initiation has an improved melt strength permitting better foam formation for extrusion foam blown with conventional blowing agents and inert gases including CO.sub.2.

Abstract: The present invention relates to porous crosslinked polymeric microbeads having cavities joined by interconnecting pores wherein at least some of the cavities at the interior of each microbead communicate with the surface of the microbead. The present invention also relates to a process for producing a porous, crosslinked polymeric microbead as well as the product of this process. This process involves combining an oil phase with an aqueous discontinuous phase to form an emulsion, adding the emulsion to an aqueous suspension medium to form an oil-in-water suspension of dispersed emulsion droplets, and polymerizing the emulsion droplets to form microbeads. At least 10% of the microbeads produced in accordance with the present invention are substantially spherical or substantially ellipsoidal or a combination of the two.

Abstract: A process is developed for recycling a polyolefin cross-linked substance having a cross-linkage, a polyolefin foamed substance free from a cross-linkage or a polyolefin foamed substance having a cross-linkage. The process includes the step of heating the polyolefin cross-linked substance together with a cross-linkage breaking agent, whereby breaking the cross-linkage to recycle the polyolefin cross-linked substance into a moldable thermoplastic resin. Further, the process includes the step of adding a foaming-agent-decomposition facilitating agent to the polyolefin foamed substance in the course of thermally melting the polyolefin foamed substance, whereby decomposing a residual foaming agent remaining in the polyolefin foamed substance.

Abstract: This invention provides a process for preparing a polyolefin resin foam, comprising the step of extruding to a low-pressure zone a melt of polyolefin resin containing a volatile blowing agent uniformly dispersed therein, the process being characterized in that the volatile blowing agent is a mixture of 5 to 95% by weight of 1,1,1,3,3-pentafluoropropane and 95 to 5% by weight of a low-boiling aliphatic hydrocarbon having a boiling point of 15.degree. C. or lower. According to the invention, there is obtainable a foam of polyolefin resin which is excellent in heat insulating property, dimensional stability and the like and which can retain them for a long term, using a blowing agent which is free of ozone-depleting risks, unlikely to adversely affect global warming, nonflammable and highly compatible with raw materials for foams.

Abstract: A urine absorber superior in smell extinguishing and urine absorption properties and in absorption stability is to be prepared. To this end, a polymer of styrene and/or conjugate diene and acrylonitrile, containing a predetermined amount of a sulfonide and/or its salts, is used as the urine absorber.

Abstract: Polymers capable of reversibly complexing carbon dioxide and other acid gases and a method of producing such polymers are disclosed. In a preferred embodiment, the present polymers incorporate amine groups capable of reversibly complexing carbon dioxide to produce an environmentally safe foamed polymer product. Because the reaction of an amine and CO.sub.2 is a reversible reaction, and because the amines are incorporated into the polymer backbone, the foamed polymers can be reverted to foamable polymers simply by collection, washing, granulating, and re-exposure to CO.sub.2. The polymers are environmentally desirable as carbon dioxide is non-toxic and is easily isolated from the atmosphere. Moreover, the process recycles the gas continually, rather than generating new gases.

Abstract: An alkyl-containing porous resin with a specific surface area of 50 to 600 m.sup.2 /g, the resin being prepared by polymerizing a monomer mixture of, based on the total weight of the monomers, 15 to 97% by weight of divinylbenzene, 0 to 82% by weight of at least one aromatic monovinyl monomer selected from the group consisting of styrene, methylstyrene and ethylvinylbenzene and 3 to 50% by weight of a vinylbenzyloxyalkane derivative represented by the formula ##STR1## wherein n is an integer of 1 to 18, a process for its preparation and its use.The porous resin of the invention is capable of fully exhibit its modified functions based on the variations of chemical and structural environments on the surface of resin, the functions being modified by introducing alkyl groups having varying chain lengths.

Abstract: The present invention relates to porous crosslinked polymeric microbeads having cavities joined by interconnecting pores wherein at least some of the cavities at the interior of each microbead communicate with the surface of the microbead. The present invention also relates to a process for producing a porous, crosslinked polymeric microbead as well as the product of this process. This process involves combining an oil phase with an aqueous discontinuous phase to form an emulsion, adding the emulsion to an aqueous suspension medium to form an oil-in-water suspension of dispersed emulsion droplets, and polymerizing the emulsion droplets to form microbeads. At least 10% of the microbeads produced in accordance with the present invention are substantially spherical or substantially ellipsoidal or a combination of the two.

Abstract: The present invention relates to compressable polymeric foam materials useful as insulation. These polymeric foams are prepared by polymerization of certain water-in-oil emulsions having a relatively high ratio of water phase to oil phase, commonly known as "HIPEs." The polymeric foam materials comprise a generally hydrophobic, flexible or semi-flexible, nonionic polymeric foam structure of interconnected open-cells. The foam structures have:(a) a specific surface area per foam volume of at least about 0.01 m.sup.2 /cc;(b) an expanded density of less than about 0.05 g/cc; and(c) a ratio of expanded to compressed thickness of at least about 3:1;wherein when the foam is compressed to 33% of its original expanded thickness and is thereafter maintained without artificial restraint on its surface, said foam will reexpand by no more than 50% after 21 days at ambient temperature (22.degree. C.).

Abstract: The present invention relates to porous crosslinked polymeric microbeads having cavities joined by interconnecting pores wherein at least some of the cavities at the interior of each microbead communicate with the surface of the microbead. The present invention also relates to a process for producing a porous, crosslinked polymeric microbead as well as the product of this process. This process involves combining an oil phase with an aqueous discontinuous phase to form an emulsion, adding the emulsion to an aqueous suspension medium to form an oil-in-water suspension of dispersed emulsion droplets, and polymerizing the emulsion droplets to form microbeads. At least 10% of the microbeads produced in accordance with the present invention are substantially spherical or substantially ellipsoidal or a combination of the two.