Navegando por Palavras-chave "kraft lignin"

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    Effect of unmodified kraft lignin concentration on the emulsion and miniemulsion copolymerization of styrene with n-butyl acrylate and methacrylic acid to produce polymer hybrid latex
    (Wiley, 2018) Messmer, Nigel Roderick [UNIFESP]; Guerrini, Lilia Mueller [UNIFESP]; Oliveira, Mauricio Pinheiro [UNIFESP]
    The introduction of non-modified kraft LignoBoost (R) lignin (KL) to produce polymer hybrid latex has received much attention in recent years because it is derived from renewable resources. The focus of this work is to develop a polymer hybrid latex by emulsion and miniemulsion copolymerization of styrene with n-butyl acrylate and methacrylic acid in the presence of different concentrations of KL furnished by the pulp and paper industry. The study intends to substitute a styrene in the system to understand the effect of non-modified KL on the properties not only of the latexes, but also on the copolymers themselves. Each polymerization was carried out by shot-process of tertbutyl hydroperoxide and sodium formaldehyde sulfoxylate as the redox system. The polymer latexes were characterized in relation to overall conversion, particle diameter, particle morphology, coagulum formation, surface tension, zeta potential, and atomic force microscopy. The polymers were evaluated through gel permeation chromatography, water absorption, and thermal properties. The results show that the addition of non-modified KL results in inhibition of the polymerization and that KL acts as a colloid stabilizer. Small particles were generated in the initial stages of the polymerizations. The presence of the KL altered the color of the latexes
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    Síntese e caracterização da poli (acrilonitrila-g-lignina) via polimerização em solução visando a obtenção de materiais carbonosos
    (Universidade Federal de São Paulo (UNIFESP), 2016-02-16) Oliveira, Taila Silverio de [UNIFESP]; Oliveira, Mauricio Pinheiro de Oliveira [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Considering the growing scientific and industrial interests involving the incorporation of organic materials from renewable sources to produce hybrids polymers, the present work aims to synthesize this class of organic/organic type, via solution polymerization of acrylonitrile (ACN) with different concentrations of Kraft lignin. This study aims to obtain poly(acrylonitrile-g-lignin) (PAL or PAN-Lig) for future application in the carbon materials production. Lignin samples obtained from different isolation methods (acid lignin: LA and basic lignin: LB) were characterized related to solubility, thermogravimetric (TGA), differential scanning calorimetry (DSC), atomic absorption spectroscopy (AAS), infrared spectroscopy with Fourier transform (FT-IR) e gel permeation chromatography (GPC). Then different mass concentrations of ACN and lignin (LA) were used in the polymerization, respectively, in the ratio of: 100/0; 90/10; 85/15; 75/25, 65/35 and 50/50, synthesizing the polyacrylonitrile (PAN) and PAN-Lig copolymers. The obtained polymers were evaluated by AAS, elemental (CNHS), TGA, DSC, solid content and polymeric global conversion, FT-IR, GPC and immediate chemical analyses. The results show that it is possible to obtain copolymers of ACN grafted with lignin and also that the lignin insertion in PAN confers good properties to the formed copolymer. Among the ratios of lignin/ACN studied, the 75/25-copolymer (PAN-25Lig) showed the most promising results to be applied as a carbon material precursor.
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    Structural, morphological, and thermal characterization of kraft lignin and its charcoals obtained at different heating rates
    (Iop Publishing Ltd, 2018) Brazil, Tayra Rodrigues [UNIFESP]; Costa, Rogeria Nunes [UNIFESP]; Massi, Marcos [UNIFESP]; Rezende, Mirabel Cerqueira [UNIFESP]
    Biomass is a renewable resource that is becoming more import due to environmental concerns and possible oil crisis. Thus, optimizing its use is a current challenge for many researchers. Lignin, which is a macromolecule with complex chemical structure, valuable physicochemical properties, and varied chemical composition, is available in large quantities in pulp and paper companies. The objective of this work is the physicochemical characterization of two Kraft lignin samples with different purities, and the study of its thermal conversion into charcoal. The lignin characterization was based on chemical, TGA, DSC, FT-IR, particle sizes, and FEG-SEM analyses. These analyses show that the lignins are mainly composed of guaiacyl and syringyl units, with residues of 30-36 wt.%, in inert atmosphere, depending on the lignin purity. From these results, the more purified lignin with higher carbon yield (%C) was selected for charcoal production. The heat treatment (HT) for carbonization of lignin, at different times (90, 180, and 420 min), resulted in different %C (41-44 wt.%). Longer HT resulted in higher %C and in charcoals with smaller pore sizes. Nanopores (similar to 50 nm) are observed for the charcoal obtained with the longest HT.