Kraft pulp produced from juvenile and mature wood from thirty-two-yearold Corymbia citriodora trees was evaluated. The stem was subdivided into regions of juvenile and mature wood, and then it was transformed into chips. These materials were then cooked in the Laboratory of Pulp and Paper at São Paulo State University (UNESP, Botucatu, SP, Brazil) and the physico-mechanical properties of the pu...

Without reclamation of waste liquor and chemicals recovery, the kraft pulp and paper industry would constitute an enormous pollution problem. Already for economical reasons, substantial recovery is secured, however, and considerable further improvements are foreseen. Recovery is outlined in terms of cycles for sodium, calcium, sulphur, and—in a wider sense—carbon. In addition, the mechanical lo...

he Technical Association of the Pulp and Paper Industry (TAPPI) sponsored a Paper InT dustry Research Needs workshop at the State University of New York, College of Environmental Science and Forestry in Syracuse, New York, May 26-28,1992, The Pulping and Bleaching Processes Panel identified the major need in kraft black liquor recovery, namely, an affordable, incremental, chemical recovery capa...

The behaviour of different cellulosic fibres during acid hydrolysis has been investigated and the levelling-off degree of polymerisation (LODP) has been determined. The study included a bleached kraft pulp (both never-dried and once-dried) and two dissolving pulps (once-dried). Additionally, cotton cellulose from new cotton sheets and sheets discarded after long-time use was studied. Experiment...

Total reduced sulfurs (TRS) include hydrogen sulfide (H2S), methyl mercaptan (methanethiol, CH3SH), dimethyl sulfide (CH3SCH3) and dimethyl disulfide (CH3S2CH3) and are referred to as noncondensible gases. They are part of a well-known environmental problem afflicting pulp mills exploiting the Kraft pulp mill process. These sulfur compounds are formed in the Kraft pulping process and come in co...

The effect of alkaline pulping parameters (temperature, effective alkali (EA) and sulphidity) on the hexenuronic acid (HexA) content of Portuguese Eucalyptus globulus pulps was studied. The HexA content was calculated on a pentosan basis. Unlike softwood pulping, the amount of this acid increased during kraft cooking and only started to decrease in the final stage of delignification (kappa numb...

Thermal and infrared spectroscopic analyzes were carried out in order to study the kind of interaction between the anatomical components of the bleached eucalyptus kraft pulp with offset inks. A Bauer-McNett fiber classifier was used in order to obtain the anatomical components of the pulp, separately. The determinations of the enthalpy of the processes occurring in the samples of inks and pulp...

A high reactivity is an essential prerequisite for dissolving pulp. In this study, xylanase modification to increase the reactivity of bamboo dissolving pulp was investigated. The original reactivity of a bamboo dissolving pulp prepared by a prehydrolysis kraft pulping process and bleached by (OP)-H-P (oxygen delignification enhanced with peroxide sodium hypochlorite peroxide) is very low. The ...

UV-Resonance Raman (UV-RR) spectroscopy with laser beam excitation source of 325 nm was applied to a solid-state study of chromophores in Eucalyptus globulus kraft pulps. The amount of chromophore structures in pre-bleached/fully bleached pulps absorbing at 325 nm linearly correlated with signal at ca 1600 cm in UV-RR spectra. The characteristic vibrations from particular pulp chromophore struc...

This study presents an equation developed to estimate, from zero and short-span tensile tests, the average length of load-bearing elements (the distance between serious defects along a fiber length) within a sheet of paper. The equation was used to examine the effect of drying treatment on the average loadbearing element length in paper made from five furnishes: two radiata pine kraft pulps, a ...