Pulp preparation

The pulps prepared by this procedure as well as the non bleached high yield bisulfite pulp have been characterized by the standard methods of the Canadian Pulp and Paper Association (CPPA Technical Section) as shown in Table I,... 

For the purpose of conversion to textile fibers, dispersions or solutions of cellulose or its derivatives are achieved by various means, in order to make possible the extrusion of the fiber-forming material through the small orifices of the spinning jets. Wood pulps prepared for these and similar uses (such as the manufacture of cellophane) are known as dissolving pulps. The manufacture of dissolving pulps is a highly developed art, with processes protected by patents or, more effectively, within company files. The purification of sulfite pulps to a degree suitable for manufacture of textile rayon (90 to 94% alpha-cellulose), tire cord (94 to 9.5% alpha-cellulose), and cellulose acetate (9.5 to 90% alpha-cellulose) requires some kind of... 

The carbohydrate analyses reported by Sundman, Saarnio and Gustafs-son for sulfate pulps are listed in Table XVII. These results were obtained by quantitative, paper chromatography on completely hydrolyzed samples. In another study,"" the uronic acid anhydride content of some wood pulps was determined. It was noted " that sulfate pulps prepared from hardwoods retain a considerable proportion of uronic acid, whereas sulfate pulps from softv oods may be entirely free from polyuronides. 

On the other hand, certain types of wood pulp, prepared by se((uences involving both acidic and alkaline treatments, show a linear relationship between gamma-cellulose and non-cellulosic polyoses. This may be illus-strated from the studies of White, Steinman and Work on acetylation pulps. Acetylation-grade pulps are usually prepared from softwoods by sulfite cooking followed by hot-caustic refining. When the total polyose content of a number of such pulps was compared with their gamma-cellulose content, a linear relationship was obtained (see Fig. 3). In spite of this excellent correlation, it cannot be assumed that all of the non-cellulosic polyoses are contained in the gamma fraction of these pulps (see below). 

Polcin and Rapson [12] have shown that hydrosulfite predominantly attacks simple quinoid, a,p-unsaturated aldehyde and anthocyanidine structures found in groundwood pulps prepared from western hemlock (Tsuga heterophylla) and eastern spruce (Picea glauca). A few years later, de Vries et al. [13,14] have demonstrated that hydrosulfite can reduce many types of aldehydes and ketones in solution according to the mechanism shown in Figure 13.1. Ketones were found to react sluggishly in water, esters are hydrolyzed, while carboxylic acids and amines are not reduced. 

Poor litter control can result in widespread contamination of the surrounding area in a way that can be offensive to all those in the neighbouihood. Problems associated with windblown litter can be minimised by the use of good operational procedures, such as the use of daily soil cover, and litter screens, while the effective sheeting of vehicles will limit problems associated with litter on the highways. Various proprietary cover materials are now available that may be used as alternatives to soil cover, and include paper-pulp preparations that may be sprayed onto the waste as a slurry, and which will, in theory, degrade when covered so that the potential for perched water tables, and preferential gas... 

Kraft pulps n. Pulps prepared in the alkaline liquor consisting of sodium hydroxide, sodium carbonate, and sodium sulfide. Also called sulfate pulp. 

Gray K, Crosby HL, Steinberg JC. Recovery of chemicals in wood pulp preparation. U.S. Patent 24,293 June 13,1956. 

No mixing of water from different fiber preparation lines and/or pulp preparation plants... 

Board Formation. Pulp prepared by any of the above processes may be used for making insulation board. Mechanical (groundwood) pulp was the first type of pulp used in large-scale production of insulation boards, and is still being used in many plants. Pulps from other sources, such as disc mills, may be... 

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