Nanoindentation study of the interfacial zone between cellulose fiber and cement matrix in extruded composites

[EN] The present study shows the application of the nanoindentation technique to evaluate the properties of the cellulose fiber-cement matrix interfacial zone in composites prepared with an auger extruder. The degree of strength of the bond between fiber and matrix is recognized as important variable that influences macro-mechanical properties, such as modulus of rupture and toughness of cement based composites. The nanoindentation measurements showed the highest hardness and elastic modulus in the part inner of the cellulosic fiber after hydration process due to precipitation and re-precipitation of cement hydration products. These results indicate that mineralization of the cellulosic fibers can affect the stress distribution and interfacial bond strength in the cement based composite.The authors acknowledge by financial support provided by Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP, process no 2013/03823-8), Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, process no 3886/2014) and Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq, process no 152069/2016), in Brazil. Special thanks for Fibria and Infibra for providing raw materials the development of this work.Teixeira, R.; Tonoli, G.; Santos, S.; Rayón, E.; Amigó, V.; Savastano, HJ.; Rocco Lahr, F. (2018). Nanoindentation study of the interfacial zone between cellulose fiber and cement matrix in extruded composites. Cement and Concrete Composites. 85:1-8. https://doi.org/10.1016/j.cemconcomp.2017.09.018S188

FABRICACIÓN DE MADERA CONTRAPLACADA CON ADHESIVO POLIURETANO ALTERNATIVO A BASE DE RICINO

En el proceso de fabricación de madera contraplacada se utilizan adhesivos. El poliuretano a base de ricino es un adhesivo de origen natural y renovable ha sido, desarrollado por el Instituto de Química de San Carlos, Universidad de San Paulo - USP. En este trabajo se estudia la utilización del adhesivo poliuterano a base de ricino, en la producción de tableros de madera contraplacada, con láminas de la especie Eucalyptus grandis. La eficiencia del adhesivo fue evaluada por ensayos físico/mecánicos, basados en las normas de la Asociación Brasileña de Normas Técnicas - ABNT. Los resultados indican que el adhesivo poliuretano a base de ricino es una alternativa viable para la producción de tableros de madera contraplacad

FABRICACIÓN DE MADERA CONTRAPLACADA CON ADHESIVO POLIURETANO ALTERNATIVO A BASE DE RICINO PRODUCTION OF PLYWOOD WITH ALTERNATIVE CASTOR OIL-BASED POLYURETHANE ADHESIVE

En el proceso de fabricación de madera contraplacada se utilizan adhesivos. El poliuretano a base de ricino es un adhesivo de origen natural y renovable ha sido, desarrollado por el Instituto de Química de San Carlos, Universidad de San Paulo - USP. En este trabajo se estudia la utilización del adhesivo poliuterano a base de ricino, en la producción de tableros de madera contraplacada, con láminas de la especie Eucalyptus grandis. La eficiencia del adhesivo fue evaluada por ensayos físico/mecánicos, basados en las normas de la Asociación Brasileña de Normas Técnicas - ABNT. Los resultados indican que el adhesivo poliuretano a base de ricino es una alternativa viable para la producción de tableros de madera contraplacadaThe plywood panels are produced with adhesives. An alternative adhesive deriving from a natural and renewable source, castor-oil-based polyurethane adhesive, developed at the Institute of Chemistry of São Carlos, University of São Paulo - USP. The study reported on here involved the use of castor oil-based polyurethane adhesive to produce plywood with the layers of wood species Eucalyptus grandis. The performance of the adhesive was evaluated based on the results of physical and mechanical tests recommended by the Brazilian Code - ABNT. The results indicate that the castor oil-based polyurethane adhesive is a promising glue for the manufacture of plywoo

Alternative castor oil-based polyurethane adhesive used in the production of plywood

Plywood is normally produced with urea-formaldehyde and/or phenol-formaldehyde adhesives. However, the former is considerably toxic and environmentally damaging, while the latter is expensive, thus motivating the search for alternative raw materials in plywood production. The castor oil-based polyurethane adhesive developed at the São Carlos Institute of Chemistry, University of São Paulo, is an environmentally friendly vegetal oil-based polymer that is harmless to humans. The wood species Eucalyptus grandis offers favorable properties for plywood the manufacture. The study reported on here involved the use of castor oil-based polyurethane adhesive to produce plywood with Eucalyptus grandis layers. The plywood's performance was evaluated based on the results of physical and mechanical tests recommended by the Brazilian code, ABNT. Tests results showed higher values than those reported in the literature and recommended by the ABNT, indicating that the castor oil-based polyurethane adhesive is a promising glue for the manufacture of plywood

Ultrasonic Measurements In Brazilian Hardwood

This paper reports on a study of the application of ultrasound waves in wood with the purpose of evaluating the latter's mechanical properties. The evaluation is based on the correlation between the speed of sound, modulus of elasticity and density. The speed of transmission is sensitive to the material's quality-determining factors; hence, this technique is an important industrial tool to improve the quality control of processes. The species used in the experimental procedure were "cupiúba" (Goupia glabra) and "jatobá" (Hymenaea sp). Tests were carried out to determine the properties of apparent density at 12% humidity content (rhoap,12%), modulus of elasticity in static deflection (E M), and modulus of rupture (MOR). Ultrasound tests were also performed to find the stiffness matrix coefficient (C LL), for purposes of comparison with the static findings. The results and analyses lead us to conclude that the nondestructive ultrasound method can be employed to obtain reliable evaluations of the mechanical properties of dicotyledons