Mário Vanoli Scatolino

Use of maize cob for production of particleboard

Os residuos agricolas sao materiais gerados em grande quantidade no Brasil, podendo se acumular no ambiente, gerando graves problemas. Um desses residuos que merecem destaque e o sabugo de milho. Uma das alternativas para o reaproveitamento do sabugo seria a producao de paineis aglomerados em mistura com madeira. Objetivou-se, neste trabalho, avaliar a viabilidade da utilizacao do sabugo de milho para a producao de paineis aglomerados. As porcentagens de sabugo de milho utilizadas foram de 0%, 25%, 50%, 75% e 100% associadas com particulas de madeira de Pinus oocarpa. Os paineis foram produzidos com 8% de ureia-formaldeido e 1% de parafina (base massa seca de particulas). Na prensagem dos paineis, foi utilizada pressao de 3,92 MPa e temperatura de 160o C por um periodo de 8 minutos. O aumento da substituicao da madeira de pinus pelo residuo sabugo de milho promoveu melhoras significativas para as propriedades de absorcao de agua, apos duas horas e inchamento em espessura, apos duas e vinte e quatro horas. As propriedades mecânicas apresentam relacao decrescente com a porcentagem de incorporacao de sabugo de milho.

Impact of nanofibrillation degree of eucalyptus and Amazonian hardwood sawdust on physical properties of cellulose nanofibril films

The production of cellulose nanofibrils (CNFs) from Amazonian wood wastes could reduce pollution and raw material costs for cellulose industry. Further studies are required to analyze the feasibility of using hardwood sawdust for the production of high-quality CNF films. Therefore, the objective of this study was to evaluate the impact of various nanofibrillation degrees of waste sawdust generated from the primary processing of different hardwood species on the physical properties of CNF films. Raw sawdust was submitted to alkaline and bleaching pre-treatments. The chemical composition of the bleached fibers was determined. The CNFs were obtained by mechanical shearing of the bleached fibers using a grinder Super MassColloider after 10, 20, 30 and 40 passages. CNFs were evaluated by transmission electron microscopy. The CNF films were formed by the casting method. Residual lignin and hemicelluloses content greatly varied among species after bleaching. No clear influence of the number of passages on apparent density was observed. None of the films was degraded in significant amounts after water immersion. Water vapor absorption (WVA) consistently decreased with more passages through the Super MassColloider for Amazonian species until 30 passages. Residual hemicelluloses of the bleached fibers adversely affected WVA. Bleached fibers made of highly purified cellulose or containing residual lignin showed lower WVA after 30 and 40 passages. Water vapor permeability showed consistent relation with the apparent density of the films. For hardwood wastes, 10–30 passages through the grinder are recommended.

Relation of transverse air permeability with physical properties in different compositions of sugarcane bagasse particleboards

Studies concerning the production of particleboards with sugarcane bagasse as an alternative fibrous material have been carried out as an attempt to provide a sustainable and viable destination for this residue. This work aimed to evaluate the influence of several processing variables related to the microstructure of sugarcane bagasse particleboards (mat type, adhesive type and adhesive content) on their permeability and water sorption properties. Air permeability data was collected by the rotameter method. Superficial air permeability ( kg), Darcian constant (k 1 ) and non-Darcian constant (k 2 ) were measured. kg was related to sorption behavior of the particleboards. 1-layer particleboards presented significantly higher kg values than the 3-layer particleboards. In general, adhesive type, position and content did not influence kg of particleboards. However, these processing variables influenced interactions between fluid and material and tortuosity of the porous media. Particleboards produced with urea-formaldehyde with high kg presented higher water absorption and thickness swelling after 24 hours. Such relations were not observed in particleboards produced with melamine-urea-formaldehyde.

Eucalyptus wood and coffee parchment for particleboard production: Physical and mechanical properties

The wood panel industry is constantly growing, being necessary the innovation in technologies and raw materials to improve the quality of the final product. Considering the shortage and pressure to decrease the dependence of wood, there is an interest in other renewable materials such as agricultural wastes. Among these wastes, coffee parchment is one which deserves notoriety. An alternative use for coffee parchment could be for production of particleboard in association with wood particles. This study aimed to evaluate the feasibility of using coffee parchment for production of particleboard. The following percentages of wastes were used: 0, 10, 20, 30, 40 and 50% in association to eucalyptus wood. The panels were produced with 8% of urea formaldehyde (based on dry weight of particles). The pressing cycle consisted by: pre-pressing of 0.5 MPa for 10 minutes followed by pressing of 4.0 MPa, and temperature of 160° C for 15 minutes. The compaction ratio of particleboards produced using higher quantities of parchment improved the physical properties. The properties of Water Absorption (2 and 24 h) and Thickness Swelling (2 h) decreased with increasing percentage of coffee parchment. The Thickness Swelling (24 h) showed not significant effect with an increase of coffee waste. The Modulus of Elasticity for coffee parchment particleboards was in the range 646.49 ± 112.65 to 402.03 ± 66.24 MPa, while the Modulus of Rupture ranged from 8.18 ± 1.39 to 4.45 ± 0.75 MPa. The results showed that 10% of coffee parchment could be added for production of particleboards.

THERMAL STABILITY OF Pinus oocarpa AND MAIZE COB PARTICLEBOARDS

Agricultural waste materials are generated in large quantities in Brazil. These can accumulate and cause serious environmental problems. One of the most commonly generated wastes in the brazilian agricultural culture is the maize cob. Being lignocellulosic in nature, the maize cob can find use as the raw material in the production of particleboards mainly concerned with furniture making. Therefore, studies regarding its thermal stability and fire resistance would be interesting. The aim of this study was to evaluate the combustibility and thermal stability of the particleboards produced from maize cob and Pinus oocarpa wood. The percentages in which maize cob was associated with Pinus oocarpa were 0%, 25%, 50%, 75% and 100%. The panels were produced using 8% urea-formaldehyde and 1% paraffin. The pressing cycle parameters included: temperature 150 °C, pressure of 3.92 MPa during 10 min. The combustibility curve analysis showed that the panels containing 25% content of maize cob had higher resistance to combustion. In general, the thermal stability decreased as the wood substitution by maize cob increased.

Particleboard Panels Produced with Different Radial Positions of Pinus oocarpa Wood

The aim of this study was to evaluate the effect of different radial regions of Pinus oocarpa wood on the physical and mechanical properties of particleboard panels. Three different radial regions (internal, intermediate and external) and the mixture (integral log) were assessed. Experimental panels were produced with a nominal density of 0.70 g/cm3 using 8% urea-formaldehyde adhesive; they were compressed at a specific pressure of 40 kgf/cm2 and temperature of 160 °C, for 8 minutes. Wood radial position affected particleboard quality and a direct influence of the chemical composition and density of the material used was observed. Only the panels produced the mixture (integral log) and with the internal region met all the requirements stipulated by the marketing standard.

Options for Chemical Modification of Wastes from a Brazilian Hardwood Species and Potential Applications

Two pathways for chemical modification of wastes from an Amazon hardwood species named Cordia goeldiana were proposed in this work. Variations in reaction time (2 h or 0.5 h) and temperature (80 and 150 °C), besides reaction medium (mechanical stirring or pressurized closed system) were tested for alkali treatment. NaOH at 5% was kept for both conditions. Afterwards, bleaching with H2O2 and NaOH was performed, but reaction conditions were held constant for both pathways. In general, the mild alkali treatment resulted mainly in the removal of extractives and hemicelluloses from the raw sawdust. The onset temperature and crystalline index increased. On the other hand, the use of higher pressure and temperature in alkali treatment at closed system had a remarkable lignin removal and crystalline index increase without changing cellulose polymorphism as the main effects, but thermal stability became lower. Apart from mineral residues removal, bleaching had negligible effects on fiber properties, suggesting that this procedure could be avoided.