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Properties of extracted Eucalyptus globulus kraft pulps

This work was a comprehensive study of the properties of extracted Eucalyptus globulus kraft pulps. Five levels of hot water extraction were performed, each followed by kraft cooking to three different kappa numbers. As extraction took place, the hemicelluloses content of the kraft pulps was reduced from 21%-22% to 3%-4% and, conversely, the cellulose fraction increased from 73%-75% to 85%-90%. Fiber length dec...

Mercury intrusion porosimetry in pulp and paper technology

Mercury intrusion is frequently used for the characterization of porous materials, giving access to parameters such as porosity and pore size distribution as well as density (skeletal and bulk).The present work aims at studying the suitability of the mercury intrusion technique to evaluate the pore structure and related information of different kinds of woods used for pulp production, pulp handsheets and commer...

Effect of extended cooking and oxigen prebleaching on the surface energy of Euc...

Efeito do cozimento e da refinação nas dimensões transversais de fibras de E. g...

O presente trabalho visa à avaliação, por meio da técnica de microscopia confocal, das alterações nas dimensões da secção reta das fibras que ocorrem com o cozimento e com a refinação, bem como à análise da influência dessas alterações em algumas propriedades das pastas e das correspondestes folhas. Os resultados obtidos são interpretados, considerando o efeito daquelas operações na parede e no lúmen das fibras...

Primary and secondary fines from Eucalyptus globulus kraft pulps. Characterizat...

The main topic of this study is the characterisation of primary and secondary fines in a chemical kraft pulp. The former were removed from an unbeaten pulp and the latter from the corresponding decrilled pulp after beating, being their size distributions measured with the Coulter-Multisizer in terms of an equivalent volume diameter. Additionally, some morphological parameters of the fibres were also determined,...

Aplicação da microscopia confocal ao estudo de fibras de E. globulus : medição ...

Cellulose Depolymerisation and Paper Properties in E. Globulus Kraft Pulps

The aim of this work was to study the impact of cellulose depolymerisation on the beating potential and handsheet properties of the portuguese E. globulus kraft pulp. A homogeneous sample of eucalypt wood chips was cooked using different kraft pulping conditions (cooking temperatures and times, and sodium hydroxide and sodium sulphide concentrations) in order to obtain a wide variation for intrinsic viscosity o...

Aplicação da microscopia confocal ao estudo de fibras de E. globulus - medição ...

Este trabalho faz parte de um estudo mais amplo que envolve a determinação, por microscopia confocal, das dimensões de fibras de pastas de E. globulus, cultivado em Portugal. Em particular, nesta publicação é abordada a implementação e aplicabilidade da referida técnica, sendo apresentados os resultados relativos a duas pastas produzidas em condições de cozimento laboratorial significativamente distintas, anali...

Monitoring the thermal efficiency of fouled heat exchangers: A simplified method

Fouling is a problem whether we are aware of it or not. In an industrial plant, it is important not only to be able to measure the buildup of unwanted deposits, but also to do it in the simplest and most economically possible way. This paper addresses the question of monitoring fouling in an oil refinery plant, where the high number of heat exchanger units and the variability of the feedstock charge pose additi...

A new approach to measuring solids concentration in mixing tanks

The solids concentration profiles in a mixing tank with mechanical agitation (axial flow impeller) have been measured using a light scattering technique associated with the refractive index matching procedure. Due to the high value of the refractive index of the particles, a new liquid mixture had been tested (70.2% ß-Pinen and 29.8% l-methylnaphtalene, v/v). The experimental profiles are compared with similar ...