Abstract: A high efficiency bleaching method for cellulosic pulp includes: (a) providing a charge of aqueous cellulosic pulp to a bleaching vessel at a consistency of from 10% to 30% along with a peroxy bleaching agent and an alkaline agent effective to adjust pH of the charge to 9.5 to 12.5; and (b) bleaching the aqueous cellulosic pulp in the bleaching vessel while maintaining a bleaching temperature of from 110° F. (43° C.) to 135° F. (57° C.) and a pH of the charge from 9.5 to 12.5 for an extended bleaching retention time. The bleaching method is advantageously used to bleach low brightness recycle pulp, and/or as part of a multistage process with bleaching stages of lesser duration, and/or as a high peroxy efficiency, low dose bleaching process or in connection with concurrently storing and bleaching pulp.

Abstract: A cooking method and a digester system wherein partly digested cellulosic fiber source is compressed during cooking to provide high molecular weight lignin and pulp.

Abstract: The present invention aims at preventing or reducing the lowering in mechanical characteristics of a carbon fiber reinforced carbon composite due to stress orientation caused by the use of a thermosetting resin as a carbon matrix precursor resin to thereby obtain a carbon fiber reinforced carbon composite improved in mechanical characteristics, and for attaining this aim, provides a process for the preparation of a carbon fiber reinforced carbon composite which comprises impregnating a carbon fiber with a bismaleimide-triazine copolymer resin instead of the sizing agent and thermoplastic resin which have been used conventionally and heating the resulting impregnated carbon fiber in a non-oxidizing atmosphere to carbonize or graphitize the resin.

Abstract: A process and apparatus for producing pulp from impregnated cellulose-containing starting materials such as wood, straw, grass, waste materials etc. in a compacting apparatus comprising a shell (1) and two mutually opposite pistons (4, 4') contained in the shell. The material to be compacted is disposed between the pistons and constitutes a resistive electrical load. The pistons are movable relative to each other and the shell is movable relative to the pistons. The impregnated starting materials are digested at a relatively low hydromodulus of 0.5 to 2 with a direct action of heat on the impregnated starting materials in the compacting apparatus at a digesting temperature of 160.degree. to 300.degree. C. The digesting times are short and depend on the digesting temperature.