Relative importance of wood density and carbohydrate content on pulping yield and product quality

O objetivo deste estudo foi avaliar a densidade b\ue1sica, a composi\ue7\ue3o qu\uedmica e as dimens\uf5es de fibras de dez amostras de madeira de Eucalyptus spp. e, verificar o impacto desse conjunto de par\ue2metros e sua combina\ue7\ue3o no rendimento do processo de polpa\ue7\ue3o kraft e na qualidade da polpa branqueada. A madeira de dez esp\ue9cies de eucalipto, com densidade b\ue1sica variando entre 365 a 544 kg/m3 e teores de carboidratos totais variando entre 70,0 a 74,5% foi transformada em polpa Kraft, com n\ufamero kappa 15,5- 16,7 e branqueada a 90% ISO por uma seq\ufc\ueancia de quatro est\ue1gios (OD(PO)D) composta de deslignifica\ue7\ue3o com oxig\ueanio (O), deslignifica\ue7\ue3o com di\uf3xido de cloro (D), extra\ue7\ue3o alcalina com per\uf3xido pressurizado (PO) e branqueamento com di\uf3xido de cloro (D). A densidade b\ue1sica da madeira mostrou melhor correla\ue7\ue3o com as dimens\uf5es da fibra e qualidade da polpa que a sua composi\ue7\ue3o qu\uedmica. Por\ue9m o rendimento depurado foi mais influenciado pela composi\ue7\ue3o qu\uedmica da madeira do que pela densidade b\ue1sica. Madeiras de menor densidade apresentaram maiores rendimentos de polpa\ue7\ue3o, mas o consumo espec\uedfico de madeira foi mais baixo para as madeiras mais densas. Os resultados de qualidade de polpa sugerem que madeiras com densidade mais baixa devam ser direcionadas \ue0 fabrica\ue7\ue3o de papel refinado (impress\ue3o e de escrita), enquanto que as mais densas sejam destinadas ao segmento de pap\ue9is sanit\ue1rios (tissue).The purpose of this study was to evaluate basic density, chemical composition and fiber dimensions of ten Eucalyptus sp wood samples and to verify the impact of this set of parameters and their combination on the Kraft pulping process yield and on bleached pulp quality. Ten eucalypt woods of different species, with basic densities varying from 365 to 544 kg/m\ub3 and total wood carbohydrate contents varying from 70.0 to 74.5%, were transformed into kraft pulp of kappa number 15,5-16,7 and bleached to 90% ISO brightness by the sequence OD(PO)D. Wood basic density showed stronger correlations with fiber dimensions and pulp quality than did chemical composition. However, pulping yield was strongly affected by chemical composition. Lighter woods resulted in higher pulping yields. However, wood specific consumption was lower for denser woods, even though these demanded more drastic pulping conditions to achieve a given kappa number. The pulp quality results suggest that lower density woods should be directed towards fabrication of refined paper (printing and writing grades) while the denser woods should be directed to the sanitary papers segment (tissue grades)

EFFECT OF WOOD CARBONIZATION IN THE ANATOMICAL STRUCTURE AND DENSITY OF CHARCOAL FROM Eucalyptus

O presente trabalho objetivou avaliar as modifica\ue7\uf5es anat\uf4micas que ocorrem com a carboniza\ue7\ue3o da madeira e determinar as propriedades anat\uf4micas, densidade b\ue1sica da madeira e densidade aparente do carv\ue3o vegetal de clones de Eucalyptus , al\ue9m de elucidar as poss\uedveis correla\ue7\uf5es significativas existentes. A microscopia eletr\uf4nica de varredura foi efetuada nas se\ue7\uf5es transversal, longitudinal tangencial e longitudinal radial da madeira e do carv\ue3o vegetal. Neste, foi feita a an\ue1lise morfol\uf3gica dos poros e densidade aparente. De uma forma geral, as caracter\uedsticas anat\uf4micas como forma de poros, raios e fibras da madeira apresentaram pouca ou nenhuma modifica\ue7\ue3o devido \ue0 carboniza\ue7\ue3o, e a superf\uedcie do carv\ue3o apresentou estruturas bem definidas. As modifica\ue7\uf5es nos elementos celulares da madeira foram principalmente referentes aos par\ue2metros quantitativos, como espessura da parede das fibras e di\ue2metro dos poros. Os clones avaliados apresentaram densidade b\ue1sica da madeira satisfat\uf3ria para a produ\ue7\ue3o de carv\ue3o vegetal. Os par\ue2metros anat\uf4micos correlacionaram-se significativamente com a densidade b\ue1sica da madeira e densidade aparente do carv\ue3o vegetal, destacando-se, neste estudo, a fra\ue7\ue3o parede das fibras.This study aimed to evaluate the anatomical changes that occur with charred wood and determine the anatomical properties, basic wood density and apparent density of charcoal Eucalyptus clones, besides elucidating the possible existing significant correlations. The scanning electron microscopy was performed in the transverse, longitudinal and tangential longitudinal and radial wood charcoal sections. In the morphological analysis of the pores and the apparent density was made. In general, the anatomical features such as pore radius and the wood fibers showed little or no change due to carbonization of coal surface and showed well defined structures. The changes in cellular elements of wood were mainly related to the quantitative parameters such as wall thickness and pore diameter fibers. The clones showed satisfactory basic density of wood for charcoal production. The anatomical parameters were significantly correlated with basic wood density and apparent density of charcoal, especially, in this study, the fraction of the fiber wall

PHYSICAL AND MECHANICAL PROPERTIES OF RECYCLED PAPERS USED FOR TUBE PRODUCTION

O presente trabalho objetivou estudar, atrav\ue9s de ensaios laboratoriais, as propriedades f\uedsicas e mec\ue2nicas de pap\ue9is reciclados utilizados para produ\ue7\ue3o de tubetes. Para tanto se utilizou seis tipos de pap\ue9is com gramatura m\ue9dia de 400 g/m2 e para os ensaios de laborat\uf3rio seguiu-se os procedimentos da Technical Association of Pulp and Paper Industry. Verificou-se diferen\ue7a significativa entre os pap\ue9is estudados quanto \ue0s caracter\uedsticas f\uedsicas e mec\ue2nicas, sendo que o papel Tipo A1 obteve, de modo geral, os melhores resultados, justificando seu alto pre\ue7o no mercado. O papel A3 foi o de maior densidade, dado relevante para ind\ufastria de tubetes, j\ue1 que estes s\ue3o geralmente comercializados por peso. Conclui-se que todos os pap\ue9is estudados s\ue3o indicados para produ\ue7\ue3o de tubetes, devendo ser utilizados de acordo com as exig\ueancias do cliente, visto que o pre\ue7o do papel \ue9 que determina, na maioria das vezes, o valor do tubete.The present study investigated, through laboratory testing, the physical and mechanical properties of recycled paper used to produce tubes. To do so, we used six types of paper with a weight average of 400 g / m2 and once the laboratory tests followed the procedures of the Technical Association of Pulp and Paper Industry. There was significant difference between the roles studied in terms of physical and mechanical characteristics, and the paper type A1 had, in general, the best results, justifying its high price in the market. The A3 has the highest density, the data relevant to industry tubes, since these are usually sold by weight. It is concluded that all of the studied papers are suitable for tube production, being used in accordance with the customer\u2019s demands, since the price of the paper is what determines, most of the time, the tube value