Expandable methyl methacrylate resin particles having a narrow particle size distribution, a good yield, and excellent expandability and formability are provided. The expandable methyl methacrylate resin particles include a base resin containing, as constitutional units, a certain amount of a methyl methacrylate unit and a certain amount of acrylic ester unit, and a blowing agent. The expandable methyl methacrylate resin particles have an average particle diameter of 0.6 mm to 1.0 mm and a particle diameter variation coefficient of not more than 20%.

The present invention relates to expanded particles and an expanded molded article. More specifically, the present invention relates to expanded particles comprising a polycarbonate-based resin as a base resin, which has a specified cell density X and a specified average cell wall thickness, as well as an expanded molded article. In addition, the present invention relates to expanded particles comprising a polycarbonate-based resin as a base resin, which has a specified bulk ratio and a specified average cell diameter, as well as an expanded molded article.

The present invention relates to thermoplastic olefin elastomer expanded beads, having an average aspect ratio of 1.10 or less and an average circularity of 0.985 or more. The thermoplastic olefin elastomer expanded beads preferably have a crystal structure such that a melting peak inherent in the thermoplastic olefin elastomer (inherent peak) and one or more melting peaks on a higher temperature side than the inherent peak (high temperature peaks) appear on a DSC curve obtained when heating the expanded beads from 23° C. to 200° C. at a heating rate of 10° C./min.

A method for producing bead foams from foam beads based on thermoplastic elastomers, especially thermoplastic polyurethane, comprises foam beads being wetted with a polar liquid and joined together thermally in a mold via high-frequency electromagnetic radiation, especially microwave radiation, and also the bead foams obtainable therefrom.

A spacer used in an electrical device that sends and receives radio waves comprises a foam that contains a resin composition containing a thermoplastic or thermosetting resin as a base resin. When the foam is not a bead foam, a ratio (B/A) of an average diameter B of central section cells relative to an average diameter A of surface layer cells is not less than 0.3 and less than 3.0. When the foam is a bead foam, a ratio (B′/A′) of an average diameter B′ of center cells relative to an average diameter A′ of outermost layer cells is not less than 0.3 and less than 3.0. Water absorption of the resin composition in a high-temperature and high-humidity environment is 2.2 mass % or less, and (εr).sup.1/2×tan δ (εr: relative permittivity, tan δ: a dielectric dissipation factor) is 0.0120 or less at 28 GHz.

A thermal insulating additive, product formed therefrom, and method of making the same, wherein the thermal insulating additive comprises a plurality of hollow polymeric particles having an average particle size up to about 0.3 micrometers. The hollow polymeric particles exhibit a mechanical strength in a compression test up to about 420 psi and a thermal conductivity that is less than 0.150 W/m-k. The hollow polymeric particles are individually formed as an alkaline swellable core that is at least partially encapsulated with two or more shell layers; the alkaline swellable core prior to swelling exhibits an average particle size that is less than about 50 nanometers.

Provided are poly(3-hydroxyalkanoate) foam particles in which a gel fraction of the whole foam particles is from 30 to 80% by weight and a difference in gel fraction between inside and outside of the foam particles is 25% by weight or less. Preferably, the foam particles are particles crosslinked by an organic peroxide. Preferably, the organic peroxide has a 1 hour half-life temperature of 114 to 124° C., contains a carbonate group, and is liquid at room temperature.

The present invention relates to thermally expandable microspheres at least partially prepared from bio-based monomers and to a process of their manufacture. The microspheres comprise a thermoplastic polymer shell encapsulating a blowing agent, wherein the thermoplastic polymer shell comprises a polymer being a homo- or copolymer of a lactone according to formula (1):

##STR00001##

wherein each of R.sub.1, R.sub.2, R.sub.3, R.sub.4, separately from one another, is selected from the group consisting of H and an alkyl group preferably with 1-4 carbon atoms. The invention further provides expanded microspheres, which can be used in a variety of applications.

A method for producing an oxo-biodegradable expanded polystyrene (EPS) product is disclosed. In embodiments, the method includes: providing a volume of polystyrene; providing a volume of one or more chemical additives; combining the volumes of polystyrene and one or more chemical additives to form a mixture; and expanding the mixture into an oxo-biodegradable expanded polystyrene (EPS) product.

A polymeric sheet, at least partially cross-linked and/or foamed, having a substantially open cell foam structure is described. A continuous method of manufacturing of an at least partially cross-linked, open cell foamed polymeric sheet is also described.