RESUMO A resina furfurílica (RF) é uma bioresina obtida a partir do álcool furfurílico (AF), extraído de fontes renováveis. Essa resina quando curada apresenta excelentes características, como elevada dureza, estabilidade química e boa resistência mecânica, que viabilizam sua utilização em diferentes áreas, destacando-se os setores aeroespacial e de bioengenharia. No entanto, a sua utilização em larga escala ainda é limitada, devido ao difícil controle do seu processo de síntese, pois a reação de policondensação do AF é extremamente exotérmica. O presente trabalho visa contribuir com a área de síntese da RF, por meio do estudo de sua obtenção em meio ácido e em baixa temperatura (∼50 ºC), variando os tempos de reação (1, 2 e 3 h), visando um maior controle da exotermia do meio reacional. O sucesso das sínteses realizadas foi comprovado por análises de espectroscopia na região do infravermelho com transformada de Fourier, que evidenciaram a presença de cetonas e estruturas de acordo com Diels-Alder e de Dunlop e Peters. Medidas de viscosidade apresentaram baixos valores (230 a 470 mPa.s), os quais são concordantes com as baixas massas molares obtidas por cromatografia de permeação em gel ( M ¯ w: ∼800 g/mol). Esses resultados mostram que as condições de síntese utilizadas desfavoreceram cineticamente o avanço da reação; porém, não promoveram picos exotérmicos. As análises termogravimétricas (TGA) das RFs curadas com ácido p-toluenosulfônico (2 e 3%, m/m) mostraram perdas de massa desde o início da análise, devido à presença de água e de frações de baixa massa molar na amostra. Esses resultados são concordantes com as imagens obtidas por microscopia eletrônica de varredura, que mostraram um elevado volume de poros. Resultados relevantes foram observados nas análises de TGA sob atmosfera inerte, com valores elevados de carbono fixo (50–60%), indicando o potencial uso das RFs sintetizadas na área de materiais carbonosos.

ABSTRACT Poly(furfuryl alcohol) (PFA) is a bioresin obtained from furfuryl alcohol (FA) extracted from renewable sources. This resin, when cured, has excellent characteristics, such as high hardness, chemical stability, and good mechanical resistance, which make its use in different areas viable, especially in the aerospace and bioengineering sectors. However, its use on a large scale is still limited due to the difficult control of its synthesis process since the polycondensation reaction of FA is extremely exothermic. The present work aims to contribute to the area of PFA synthesis, through the study of its obtainment in acidic medium and at low temperature (∼50 ºC), varying the reaction times (1, 2, and 3 h), aiming at greater control of the exothermy of the reaction medium. Fourier transform infrared spectroscopy analyses confirmed the syntheses success, which showed the presence of ketones and structures according to Diels-Alder and the Dunlop and Peters. Viscosity measurements showed low values (230 to 470 mPa.s), which are in agreement with the low molar masses obtained by gel permeation chromatography ( M ¯ w: ∼800 g/mol). These results show that the synthesis conditions used kinetically unfavored the progress of the reaction but avoided exothermic peaks. Thermogravimetric analysis (TGA) of the PFAs cured with p-toluenesulfonic acid (2 and 3%, w/w) showed mass losses since the beginning of the analysis due to the presence of water and low molar mass fractions in the sample. These data agree with the images obtained by scanning electron microscopy, which showed a high volume of pores. Relevant results were observed in the TGA analysis under an inert atmosphere, with high values of carbon yield (50–60%), indicating the potential use of synthesized PFAs in the area of carbon materials.

Abstract Environmental friendliness and cost demand the development of lignin-modified phenolic (LPF) resins for application as a binder for carbon-containing refractories (CCRs) production. Moreover, the in-situ graphitization of such resins can produce crystalline carbon, which is an essential component of CCRs. Consequently, this study investigated LPF resins graphitization using ferrocene, boron oxide and boric acid. The modified resins were synthesized using thermally treated kraft lignin based on 1.5 formaldehyde to phenol molar ratio and with up to 30 wt.% lignin as phenol replacement. The resins chemical composition and the structural organization and oxidation resistance of carbons derived from the plain resins and those containing the graphitizing additives were determined. The results showed that ferrocene and the boron compounds could induce graphitic carbon generation when carbonizing LPF resins at 1500 °C for 5 hours. The best graphitization level (73%) was achieved when 10 wt.% boric acid was added to the resin produced with 20 wt.% lignin. Regarding the formulations containing ferrocene, the highest amount of graphitic carbon (48%) was generated when 5 wt.% of this additive was added to the resin synthesized with 10 wt.% lignin. The carbons derived from the formulations containing boron oxide presented the best oxidation resistance.

ABSTRACT This study evaluates the thermal, morphological and mechanical behavior of polypropylene (PP) composite with different natural fibers. The fibers used were wood, sugarcane, bamboo, babassu, coconut and kenaf with and without coupling agent. The thermal, morphological and mechanical properties were evaluated, and a composite PP+GFPP (glass fiber) was used as reference. The interaction at the interface fiber-polymer matrix was studied by scanning electron microscopy (SEM) at the fractured surface of the composites, as expected the presence of maleic anhydride (MA) as coupling agent increasedthe interaction at the interface. The influence of natural fiber in the degree of crystallinity of the composites was evaluated by DSC analysis. The samples of PP+GFPP and PP+(PP-MA)+WF (wood flour) showed better temperature stability. PP+GF also presented superior flexural modulus. The thermal dynamic mechanical behavior was evaluated by DMA, a decrease in storage modulus with increasing temperature was observed, the PP+GF and the composite containing maleic anhydride and sugarcane fiber showed higher modulus. The natural fiber biocomposites studied, consistently presented lower flexural modulus and tensile strength than the reference composite, with and without the use of coupling agent. As expected the use of natural fibers lowered the density compared to the reference material.

El objetivo de este trabajo fue esterificar pulpa refinada procedente de bambú industrial kraft, pre-tratados con hidróxido de sodio y disolventes orgánicos para producir materiales menos hidrofÃlicos. Con el fin de verificar la aparición de reacción de esterificación, espectroscopia infrarroja, análisis termogravimétrica, análisis elemental y absorción de agua fueron realizadas. Después de la reacción, el espectro infrarrojo mostró bandas relacionadas con los grupos éster y grupos de ácido carboxÃlico, que muestra el intercambio de grupos OH por grupos éster. Esta pruebla también mostró una proporción reducida de la absorbancia debido a la presencia del grupo éster causando una reducción en el Ãndice de cristalinidad de la muestra. Estos resultados se corroboraron por un aumento en la cantidad de contenido de carbono después del análisis elemental. En la prueba de absorción de agua, la pulpa modificada con dianhÃdrido mostró el nivel más bajo en comparación con otras muestras. El análisis termogravimétrica mostró también una reducción en la temperatura de inicio de la degradación de pulpa refinada, asà como una disminución en el contenido de humedad, los eventos que demostraron la eficacia de la modificación utilizando BTDA dianhÃdrido.

Bamboo admittedly and engineering material widely used for buildings in several countries. However, lack of good interfacial adhesion, low melting point, and poor resistance towards moisture make the use of natural fiber reinforced composites less attractive. The aim of this work was esterify the refined pulp of bamboo came from kraft industrial pulping, previously treated with sodium hydroxid and organic solvents for the production of less hydrophilic materials. In order to verify the occurrence of reaction, assays of spectroscopy in the region of IV, thermogravimetry, elementary analysis and water absorption were performed. After the reaction, the infrared spectra presented bands related to the ester and carboxylic acid groups, evidencing the exchange of OH groups for ester groups. This test also shows a decrease in the absorbance ratio due to the presence of ester group causing a reduction in the crystallinity index of the sample. These results were proven by the gain in the value of carbon content after the elementary analysis. In the water absorption test, the pulp modified with dianhydride showed the lowest level as compared to other samples. The thermogravimetric analysis also showed a decrease in initial temperature of pulp degradation, as well as decrease in the moisture, facts that proved the efficiency in the modification using dianhidrido BTDA.

Nowadays the interest in polymeric composites reinforced with vegetal natural fibers in substitution for manufactured fibers is increasing. This is due to the fact that vegetal fibers are less abrasive, biodegradable, present low density and excellent mechanical and thermal properties. Several vegetal fibers have been used for various types of composites among which the bamboo differs from these fibers in being widely used for cellulose and paper industrial production. This paper presents the results of recent researches about fiber and pulps of bamboo, which were submitted to several types of tests, aiming at a better understanding of their properties. The main objective of this study was to physical-chemical characterize fiber and bamboo pulps, disseminating their properties and maximizing their use in polymeric applications. Most of the samples were analyzed and characterized using the methods recommended by the American Society for Testing and Materials, ASTM and the Technical Association of the Pulp and Paper Industry, TAPPI. The results show that the refined pulp was more suitable to be used as a reinforcing agent in polimeric composites instead of the unrefined pulp and natural fiber.

Atualmente é crescente o interesse pelos compósitos poliméricos reforçados com fibras naturais vegetais em substituição às fibras manufaturadas. Isto se deve ao fato das fibras vegetais serem menos abrasivas, biodegradáveis, apresentar baixa densidade e excelentes propriedades mecânicas e térmicas. Várias fibras vegetais vêm sendo utilizadas nos mais variados tipos de compósitos, dentre as quais as de bambu se diferenciam por serem largamente utilizadas na produção industrial de celulose e papel. Este trabalho apresenta os resultados de recentes pesquisas envolvendo fibra e polpas de bambu, as quais foram submetidas a vários tipos de ensaios, visando um maior conhecimento de suas propriedades. O principal objetivo deste estudo foi caracterizar físico-quimicamente fibra e polpas, difundindo suas propriedades e maximizando sua utilização em aplicações poliméricas. Grande parte das amostras foram analisadas e caracterizadas utilizando as metodologias preconizadas pela American Society for Testing and Materials, ASTM e pela Technical Association of the Pulp and Paper Industry, TAPPI. Os resultados mostram que a polpa refinada se apresentou mais adequada para ser utilizada como agente de reforço em compósitos poliméricos em detrimento da polpa sem refino e fibra natural.

Neste estudo, avaliou-se a capacidade da madeira Paraju (Manilkara longifolia), modificada quimicamente, para a retenção de íons metálicos. A modificação refere-se a um tratamento com ácido cítrico que leva à reação de grupos carboxilato com a celulose da biomassa. A introdução desses grupos foi observada através de espectrometria de infravermelho. Foram realizados ensaios em sistemas de batelada contendo cádmio e cobre. Os ensaios foram conduzidos em condições de equilíbrio, ajustados segundo o modelo de Langmuir. Obteve-se um carregamento máximo nos sistemas contendo apenas um metal, de 0,56 mmol-Cd/g e 0,94 mmol-Cu/g. O carregamento de cádmio reduziu-se de 0,56 mmol-Cd/g para 0,21 mmol-Cd/g, à medida que a concentração de cobre cresceu no sistema mostrando que existe uma competição entre os metais pelos grupos de troca.

In the present work, the exchange capacity of Manilkara longifolia sawdust, chemically modified, was studied. The modification was carried out by a chemical treatment with citric acid, which introduced carboxilate groups in the material surface. The introduction of these groups was confirmed by infrared spectroscopy. Cadmium and copper sorption was studied batchwise. Isotherms were drawn and adjusted to the Langmuir model. Maximum loadings of 0.56 mmolCd/g and 0.94 mmolCu/g were achieved in single metal adsorption. Cadmium uptake was reduced from 0.56 mmolCd/g to 0.21 mmolCd/g as the copper concentration increased in the reaction system. These results show that there is a competition between the two metals for the exchange sites.

O presente trabalho trata da obtenção e caracterização de blendas envolvendo matrizes asfálticas (CAP 20), em misturas com poliestireno reciclável (PS), pó de pneu (PPN) e lignina organossolve (LIG). Quando se adicionam polímeros à matriz asfáltica, pretende-se, principalmente, aumentar a impermeabilidade, impedindo a deterioração pela água, diminuir a fragilidade a baixas temperaturas e diminuir o desgaste por abrasão. As propriedades físicas, incluindo índice de penetração, ponto de amolecimento e índice de susceptibilidade térmica do CAP 20 modificado, foram analisadas e comparadas com o CAP 20 não modificado. Os resultados obtidos mostram que a adição de PPN, PS e LIG afeta as propriedades mecânicas das blendas formadas com o CAP 20, diminuindo os índices de penetração e aumentando os pontos de amolecimento de uma maneira geral.

The present work describes the production and the characterization of blends involving mixtures of CAP 20 with recycled polystyrene, tire powder or organosolve lignin. The main objective related with the modification of the asphalt matrixes is to increase the impermeability impeding water deterioration, to reduce the fragility for low temperatures and to reduce the abrasion phenomena. The physical properties, including penetration index, softening point and index of thermal susceptibility were analyzed and then compared with CAP 20 matrix. The main results show that the addition of tire powder, polystyrene and lignin affect the mechanical properties of the blends when compared with CAP 20, showing a general decrease of penetration and a general improvement of the softening point after addition of modifiers.