Cellulose fibers are impregnated with polyethyleneimine so that the impregnation forms a type of network, which can reduce the specific resistance of the cellulose material owing to the electrical conductivity of the network. The cellulose material can thereby be advantageously adapted to use as electrical insulation of transformers, the cellulose material in this case being soaked in transformer oil. An adaptation of the specific resistance of the cellulose material to the specific resistance of the oil lead to improved dielectric strength of the transformer insulation. A method for impregnation of the cellulose material is described.

A prepreg includes; sizing agent-coated carbon fibers coated with a sizing agent; and a thermosetting resin composition impregnated into the sizing agent-coated carbon fibers. The sizing agent includes an aliphatic epoxy compound (A) and an aromatic compound (B) at least containing an aromatic epoxy compound (B1). The thermosetting resin composition includes a thermosetting resin (D) and a latent hardener (E), and optionally includes an additive (F) other than the thermosetting resin (D) and the latent hardener (E). The (a)/(b) ratio is within a predetermined range where (a) is the height of a component at a binding energy assigned to CHx, C—C, and C═C and (b) is the height of a component at a binding energy assigned to C—O in a C.sub.1s core spectrum of the surfaces of the sizing agent-coated carbon fibers analyzed by X-ray photoelectron spectroscopy.

A novel method of fabricating carbon nanotube sheet scrolled fiber and fiber tows (carbon, graphite, glass, natural polymer, synthetic polymer, metallic, silicon carbide, Kevlar, etc.) in composites with improved interfacial shear strength, compressive strength, yield strength, stiffness and toughness has been reported. Single or multiple layers of carbon nanotube sheet, with a bias/wrapping angle of 0° and 90°, has been scrolled around single fiber and fibers tows to improve the above mentioned mechanical properties of the matrix surrounding the fiber. Other common methods of growing CNTs directly on the fibers actually damage the fiber surface during the required precursor deposition and CNTs growth process. This demonstrated solid-state method overcomes such known problems. The CNTs sheet scrolled fiber is embedded into the polymer matrix exhibits significant (80%) increase in interfacial shear strength, compressive strength and toughness.

Fibers, prepreg materials, compositions, composite articles, and methods of producing composite articles are disclosed herein. A fiber may include at least one polymeric fiber and a plurality of carbon nanotubes. The at least one polymeric fiber extends in a lengthwise direction. The at least one polymeric fiber is a nanofiber.

The present invention is a low dielectric resin substrate, which is a composite including an annealed quartz glass cloth and an organic resin, where the annealed quartz glass cloth has a dielectric loss tangent of less than 0.0010 at 10 GHz, and tensile strength of 1.0 N/25 mm or more per cloth weight (g/m.sup.2). This provides a resin substrate that includes a quartz glass cloth which has a low dielectric loss tangent and which is also excellent in tensile strength.

A prepreg, which includes a carbon fiber reinforced material, has excellent Mode I interlaminar toughness, Mode II interlaminar toughness, and tensile strength. The prepreg includes the following constituents [A] to [C] and satisfies the following conditions (I) and (II): [A]: a carbon fiber; [B]: an epoxy resin; and [C]: a hardener for [B], and (I) a surface oxygen concentration O/C of [A] measured by X-ray photoelectron spectroscopy is 0.10 or more; and (II) a cured product obtained by curing [B] and [C] includes a resin region having molecular anisotropy exhibiting interference fringes in polarizing microscope observation in a crossed Nicol state.

A matrix resin composition for fiber reinforced composite materials is described. The resin is thermosetting and achieves a glass transition temperature of at least 177° C. (Tg), obtained by curing under anaerobic conditions at room temperature. The matrix resin will streamline composite fabrication processes by eliminating the need for heating during the cure process. The implications of this development are significant in terms of the ease of use and elimination of procedural steps. While the resin system was developed specifically for vacuum bagging, it is expected to be viable for other composite fabrication methods including resin transfer molding (RTM) and vacuum-assisted resin transfer molding (VARTM). The resin system is viable for use with carbon fiber reinforcements to fabricate laminates at least 0.20 inches thick. The resulting laminates have low porosity and mechanical properties equivalent to those prepared with common epoxy matrix resins.

The present invention is an annealed quartz glass cloth that has an SiO.sub.2 content of 99.5 mass % or more, a dielectric loss tangent of less than 0.0010 at 10 GHz, and a tensile strength of 1.0 N/25 mm or more per cloth weight (g/m.sup.2). This provides an annealed quartz glass cloth that has a low dielectric loss tangent and that is also excellent in tensile strength; and a method for manufacturing an annealed quartz glass cloth by which strength recovers after a high-temperature heat treatment.

The present invention relates to a laminated film for fiber adhesion and/or fiber sheet surface protection in which a layer [I] containing a thermosetting composition [i] and a support film [II] are laminated, wherein the thermosetting composition [i] contains a thermal polymerization initiator (C) having a 10-hour half-life temperature of 65° C. or higher.

Some embodiments of the present disclosure relate to an article comprising a reinforced glass mat. In some embodiments, the reinforced glass mat includes a glass mat and a reinforcement material. In some embodiments, the glass mat includes a web of glass fibers. In some embodiments, the reinforcement material is embedded into the web of glass fibers of the glass mat. In some embodiments, the reinforced glass mat includes a sufficient amount of the reinforcement material, so as to result in a nail shank shear resistance of 13 lbs to 17 lbs, when the article is tested according to ASTM 1761 at 140° F. Methods of making the article, specific embodiments of the reinforcement material in the form of a polymeric binder, and methods of forming a roofing shingle from the article are also disclosed.