Viviane da Costa Correia

Grinding process for the production of nanofibrillated cellulose based on unbleached and bleached bamboo organosolv pulp

Nanofibrillated cellulose (NFC) is a type of nanomaterial based on renewable resources and produced by mechanical disintegration without chemicals. NFC is a potential reinforcing material with a high surface area and high aspect ratio, both of which increase reinforcement on the nanoscale. The raw materials used were unbleached and bleached bamboo organosolv pulp. Organosolv pulping is a cleaner process than other industrial methods (i.e. Kraft process), as it uses organic solvents during cooking and provides easy solvent recovery at the end of the process. The NFC was produced by treating unbleached and bleached bamboo organosolv pulps for 5, 10, 15 and 20 nanofibrillation cycles using the grinding method. Chemical, physical and mechanical tests were performed to determine the optimal condition for nanofibrillation. The delamination of the S2 layer of the fibers during nanofibrillation contributed to the partial removal of amorphous components (mainly lignin), which have low polarity and improved the adhesion of the fibers, particularly the unbleached cellulose. The transverse modulus of elasticity of the unbleached NFC was highest after 10 nanofibrillation cycles. Further treatment cycles decreased the modulus due to the mechanical degradation of the fibers. The unbleached NFC produced by 10 cycles have a greater transverse modulus of elasticity, the crystallite size showed increase with the nanofibrillation, and after 5 nanofibrillation cycles, no differences are observed in the morphology of the fibers.

Bamboo cellulosic pulp produced by the ethanol/water process for reinforcement applications

A polpacao organossolve e o processo quimico limpo que utiliza solventes orgânicos para remocao de lignina e hemicelulose de materias-primas lignocelulosicas. Esse metodo proporciona a facilidade de recuperacao do solvente no final do processo. Neste trabalho foi produzida polpa celulosica de bambu pelo processo organossolve, avaliando diferentes temperaturas e tempos de reacao, e as polpas foram analisadas visando a futura aplicacao para reforco de compositos. A producao de polpa de bambu pelo processo organossolve foi estudado variando as condicoes de cozimento de 1, 2 e 3 h a 150, 170 e 190° C, a fim de alcancar as condicoes ideais de rendimento e caracteristicas quimicas e fisicas da polpa para a potencial aplicacao em reforco de compositos. Os melhores resultados para a deslignificacao (numero de kappa 38), com a degradacao da fibra relativamente baixa (viscosidade de 625 cm3 g-1), razao de aspecto de 40,4 e o indice zero span de 204 Nm g-1, foram obtidos pelo processo de polpacao a 190°C durante 2h. Essa condicao de polpacao pode ser considerada como a mais adequada em relacao aos demais intervalos de tempo estudados no presente trabalho. A maior resistencia mecânica e menor incidencia de defeitos morfologicos na fibra (6,0% de curls e de 10,6% de kinks) podem demonstrar o potencial da polpa organossolve bambu como elemento de reforco.

Macro, Micro and Nanoscale Bamboo Fiber as a Potential Reinforcement for Composites

Vegetal fibers are obtained from leaves, stalks, culms, fruit and seeds, and have been used in the macro, micro and nanoscale as partial replacement of synthetic fibers in organic and inorganic matrices. Bamboo has high strength fibers, and is one of main nonwood resources and is available in tropical areas worldwide. These characteristics justify the study and application of bamboo fiber as reinforcement in the macro, micro and nanoscale. The macrofibers were obtained from bamboo culms, the microfibers from the chemical pulping and the nanofibers were obtained from the mechanical nanofibrillation of the pulp. The fibers were subjected to chemical, physical, mechanical and morphological tests. There was modification in the chemical composition of the bamboo after pulping, such as decrease of amount of the lignin, hemicellulose and extractives in 42.4%, 33.3% and 83.7%, respectively.The bamboo fibers width have been reduced from 0.26 mm to 19.8 μm after pulping and after nanofibrillation process the width was reduced from 19.8 μm to 16.2 nm.The decrease of the fibers dimension can be seen from the micrographs and analyzing it mechanical properties, the bamboo fibers are a reinforcement potential in macro, micro and nanoscale to organic and inorganic matrices.

POLPA CELULÓSICA DE BAMBU PRODUZIDA PELO PROCESSO ETANOL/ÁGUA PARA APLICAÇÕES DE REFORÇO

Organosolv pulping is the clean chemical process of using organic solvents to aid in the removal of lignin and hemicellulose from lignocellulosic raw materials. This method provides facility for solvent recovery at the end of the process. In this work, it was to produce bamboo cellulosic pulp by the organosolv process evaluating different temperatures and reaction times, and the pulps were analyzed aiming their future application in the reinforcement of composites. The production of bamboo pulp by the organosolv process was studied varying the cooking conditions at 1, 2 and 3 h and 150, 170 and 190 o C of temperature, in order to achieve the ideal conditions of yield, chemical and morphological characteristics of the pulp for its potential application in the reinforcement of composites. The best results for delignification (kappa number of 38), with relatively lower fiber degradation (viscosity of 625 cm 3 g -1 ), aspect ratio of 40.4 and the index zero-span of 204 Nm g -1 , were achieved for the pulping process at 190 o C for 2 h. These pulping conditions can be considered as the more appropriate in the range of time intervals evaluated in this work. The higher mechanical strength and the lower incidence of morphological defects in the fiber (6.0% of curls and 10.6% of kinks) can demonstrate the potential of organosolv bamboo pulp as a reinforcing element.