A random mat material including fiber bundles, said fiber bundles including fibers having an average fiber length of 5 to 100 mm, and having an average number N of fibers in the fiber bundle that satisfies:

[00001]$\frac{1.5{10}^5}{D^2}<N<\frac{4.5{10}^5}{D^2}$

wherein D is the average diameter of fibers in the fiber bundle, expressed in micrometers, and the standard deviation SD.sub.N of the number of fibers in a fiber bundle satisfies:

1,000<SD.sub.N<6,000

wherein at an end of the fiber bundle, the number of the fibers in a fiber bundle becomes less from center to edge of the fiber bundle in a fiber direction.

A random mat material including fiber bundles, said fiber bundles including fibers having an average fiber length of 5 to 100 mm, and having an average number N of fibers in the fiber bundle that satisfies:

[00001]$\frac{1.5{10}^5}{D^2}<N<\frac{4.5{10}^5}{D^2}$

wherein D is the average diameter of fibers in the fiber bundle, expressed in micrometers, and the standard deviation SD.sub.N of the number of fibers in a fiber bundle satisfies:

1,000<SD.sub.N<6,000

wherein at an end of the fiber bundle, the number of the fibers in a fiber bundle becomes less from center to edge of the fiber bundle in a fiber direction.

An electrode used in a battery system, the electrode including a sheet made of a nonwoven fabric containing a plurality of carbon fibers. The sheet includes a first surface and a second surface that face each other in a direction along a thickness of the sheet, the plurality of carbon fibers include a first carbon fiber, the first carbon fiber includes at least one of a cut section facing the first surface and a cut section facing the second surface, a width of the sheet is less than or equal to 1000 mm, and a length of the sheet is less than or equal to 2000 mm.

An activated carbon fiber is obtained by activating: a polyphenylene ether fiber that contains a polyphenylene ether component having a rearrangement structure connected by a bond at an ortho-position in a repeating unit continuously bonded at a para-position; an infusibilized polyphenylene ether fiber obtained by infusibilizing the polyphenylene ether fiber; a flameproofed polyphenylene ether fiber obtained by flameproofing the polyphenylene ether fiber or the infusibilized polyphenylene ether fiber; or a carbon fiber obtained by carbonizing any of the polyphenylene ether fibers.

An activated carbon fiber is obtained by activating: a polyphenylene ether fiber that contains a polyphenylene ether component having a rearrangement structure connected by a bond at an ortho-position in a repeating unit continuously bonded at a para-position; an infusibilized polyphenylene ether fiber obtained by infusibilizing the polyphenylene ether fiber; a flameproofed polyphenylene ether fiber obtained by flameproofing the polyphenylene ether fiber or the infusibilized polyphenylene ether fiber; or a carbon fiber obtained by carbonizing any of the polyphenylene ether fibers.

The invention relates to electrospun three-dimensional (3D) nanofibrous scaffolds (with controllable porosities as high as about 96%) and methods of preparing the same. The electrospun 3D scaffolds possess interconnected and hierarchically structured pores with sizes ranging from tens of nanometers to hundreds of micrometers. In embodiments, the 3D scaffolds can be biocompatible and/or biodegradable. In some embodiments, the 3D scaffolds can be conductive. In some embodiments, the 3D scaffolds can contain bioactive species.

The invention relates to electrospun three-dimensional (3D) nanofibrous scaffolds (with controllable porosities as high as about 96%) and methods of preparing the same. The electrospun 3D scaffolds possess interconnected and hierarchically structured pores with sizes ranging from tens of nanometers to hundreds of micrometers. In embodiments, the 3D scaffolds can be biocompatible and/or biodegradable. In some embodiments, the 3D scaffolds can be conductive. In some embodiments, the 3D scaffolds can contain bioactive species.

A random mat includes a chopped fiber bundle [A] obtained by obliquely cutting a partially separated fiber bundle [B] prepared by alternately forming separation-processed sections, each of which is separated into a plurality of bundles, and not-separation-processed sections, along the lengthwise direction of a fiber bundle, wherein the total cross-sectional area of reinforcing fibers exhibits a specific change amount between both tips of the chopped fiber bundle [A]; a production method produces the random mat; and a fiber-reinforced resin molding material uses the random mat.

A fiber-reinforced resin forming material contains at least a matrix resin and bundled aggregates of discontinuous reinforcing fibers, wherein: the bundled aggregates include both reinforcing fiber aggregates A having a shape formed by cutting after having performed a splitting treatment to completely split the strands of continuous reinforcing fibers into a plurality of bundles of strands, and reinforcing fiber aggregates B1 having a shape that includes unsplit parts where splitting treatment was inadequate and/or reinforcing fiber aggregates B2 having a shape not subjected to splitting treatment; and both the ratio of the weight of the reinforcing fiber aggregates B1 with respect to the total weight of reinforcing fibers in the fiber-reinforced resin forming material, and the ratio of the total weight of the reinforcing fiber aggregates B1 and the reinforcing fiber aggregates B2 with respect to the total weight of reinforcing fibers in the fiber-reinforced resin forming material, are 50-95%.

A fiber-reinforced resin forming material contains at least a matrix resin and bundled aggregates of discontinuous reinforcing fibers, wherein: the bundled aggregates include both reinforcing fiber aggregates A having a shape formed by cutting after having performed a splitting treatment to completely split the strands of continuous reinforcing fibers into a plurality of bundles of strands, and reinforcing fiber aggregates B1 having a shape that includes unsplit parts where splitting treatment was inadequate and/or reinforcing fiber aggregates B2 having a shape not subjected to splitting treatment; and both the ratio of the weight of the reinforcing fiber aggregates B1 with respect to the total weight of reinforcing fibers in the fiber-reinforced resin forming material, and the ratio of the total weight of the reinforcing fiber aggregates B1 and the reinforcing fiber aggregates B2 with respect to the total weight of reinforcing fibers in the fiber-reinforced resin forming material, are 50-95%.