Abstract: Provided is a polyfunctional vinyl aromatic copolymer having reactivity and solubility that can be used for manufacturing a copolymer rubber and a copolymer rubber material having processability, strength and homogeneity obtained therefrom. The polyfunctional vinyl aromatic copolymer includes: 0.5 mol % or more and 40 mol % or less of a structural unit (a) derived from a divinyl aromatic compound and 60 mol % or more and 99.5 mol % or less of a structural unit (b) derived from a monovinyl aromatic compound, in which at least some of the structural units (a) are a crosslinked structural unit (a2) represented by the following Formula (2) and a vinyl-group-containing structural unit (a1) represented by the following Formula (1): in the formulas, R1's independently represent an aromatic hydrocarbon group having 6 to 30 carbon atoms.

Abstract: This disclosure relates to an electrically insulating filler for sheathed heaters. The filler includes globular and nonglobular particles containing at least 95 wt. % MgO, and the percentage of globular particles being at least 5 wt. %. The globular magnesia includes at least one single magnesia or a combination of magnesias selected from groups of sintered magnesias and electro-fused magnesias.

Abstract: A method of manufacturing silicon carbide crystals in which a rice husk raw material is pretreated with an acid solution (e.g., 5N to 6N H.sub.2 SO.sub.4, HCl or HNO.sub.3) prior to being heated in a furnace of non-oxidizing atmosphere. Pretreatment of the rice husks in this manner results in silicon carbide crystals of high purity.

Abstract: A method of manufacturing silicon nitride whiskers in which a carbon and silicon containing material having a thin configuration and sufficient porosity to permit both the passage of a gas therethrough and to provide spaces for growing whiskers therein is charged on a gas-permeable tray, and heated in a furnace of non-oxidizing atmosphere. The tray is moved intermittently through a series of temperature zones, increasing stage-by-stage from about 400.degree. C. to 1,300.degree. C., while a non-oxidizing gas is circulated through the porous material to remove any impurities. Thereafter, the heated tray is intermittently moved through a series of increasing temperature stages from about 1,350.degree. C. to 1,450.degree. C. in the presence of a flow of nitrogen gas to effect whisker growth. The heat-treated silicon nitride-containing material is dispersed in a two-phase mixture of a hydrophobic organic liquid and water. The desired silicon nitride whiskers can be isolated from the aqueous phase.

Abstract: A method of manufacturing silicon carbide whiskers in which a carbon and silicon containing material having a thin configuration and sufficient porosity to permit both the passage of a gas therethrough and to provide spaces for growing whiskers therein is charged on a gas-permeable tray, and heated in a furnace of non-oxidizing atmosphere. The tray is moved intermittently through a series of temperature zones, increasing stage-by-stage from about 400.degree. C. to 1,300.degree. C., while a non-oxidizing gas is circulated through the porous material to remove any impurities. Thereafter, the heated tray is intermittently moved through a series of increasing temperature stages from about 1,350.degree. C. to 1,450.degree. C. to effect whisker growth. The treated silicon carbide-containing material is dispersed in a two-phase mixture of a hydrophobic organic liquid and water. The desired silicon carbide whiskers can be isolated from the aqueous phase.