The bottleneck of hemicellulose as a bio-based material is its processability and property drawbacks (softening and hydrophilicity). Thus, mixing other biopolymers can be an alternative. This article proposes blending hemicellulose (10−50 wt%) with polyhydroxybutyrate (PHB) and poly (lactic acid) (PLA), using acetic acid and chloroform as casting solvents to improve its processability and thermal properties. The materials were thermally (TGA - thermogravimetric analysis), chemically (FTIR - Fourier transformer infrared) and morphologically (SEM - scanning electron microscopy) characterized. Finally, a multicriteria decision analysis (MCDA) evaluated the materials’ properties to identify the optimum combination (casting solvent, biopolymer and hemicelluloses proportion) for producing an optimal blend. The MCDA established that the blend of hemicellulose:PHB (10:90 wt/wt) produced with acetic acid was optimum considering melting temperature and the crystallinity criteria. Moreover, higher hemicellulose concentration in the blends decreased the MCDA success rate, indicating the worst properties. PLA blends showed a higher degradation temperature than PHB. The PHB blends produced with acetic acid demonstrated improved properties when compared to chloroform, revealing its potential as a solvent.

Abstract The lack of knowledge about the behavior under creep and fatigue limits the use of polymeric composites reinforced with natural fibers. Thus, this work assessed the behavior of epoxy composites reinforced with sisal fibers under tensile, fatigue, and creep tests. Also, thermogravimetry and scanning electron microscopy assessed the sodium hydroxide (NaOH) treatment efficiency in sisal fibers. Further, differential scanning calorimetry determined the degree of cure of the composites, and stereomicroscopy allowed the evaluation of the surface’s fracture. As a result, the tensile strength of the composite was 1.4 times the value of neat epoxy resin after 100,000 cycles in the fatigue test. Moreover, when loaded with 20% of the maximum tensile strength, it is estimated that the composite resists 200,000 h without rupturing by creep. To conclude, the efficient adhesion between sisal fibers and epoxy obtained by NaOH treatment allowed good mechanical behavior to the epoxy composite.

Abstract Qualitative and quantitative measuring in water bodies, nuclear medicine, agriculture, and world oil production use tracers to monitor, evaluate and continuously improve their processes. The bibliometric information about the past and the future of artificial tracers, to monitor surface and groundwater by using sustainable biodegradable materials it will be important for future generation. To fulfil this purpose, bibliometric literature analysis has been considered as a solution to identify research areas that need to be improved. The results of this paper showed that even with the increase in research in biopolymers, and the use of artificial tracers, academic development is still not significant. The United States, China, and Germany are the top publishers in this field however, there is no country that constantly develops research in these areas concomitantly using biodegradable polymers. Because of that, this field could be further explored, globally using innovative techniques and materials for new tracers.

RESUMO O objetivo deste trabalho foi caracterizar os compósitos produzidos com o terpolímero acrilonitrila-butadieno-estireno (ABS) reforçados com fibras de polpa celulose modificadas com nanopartículas de sílica (SiO2). Primeiramente, as fibras foram modificadas utilizando o processo sol-gel, tendo como precursor da sílica o ortosilicato de tetraetila (TEOS). Adicionalmente, duas concentrações de TEOS e dois tempos de reação foram utilizados para produzir dois tipos de fibras modificadas, FT1 e FT2, logo depois, foi determinado o rendimento de cada processo de modificação. As fibras foram caracterizadas por meio da microscopia eletrônica de varredura (MEV), análise termogravimetria (TGA) e sua derivada (DTG). Depois da obtenção das fibras os compósitos de acrilonitrila-butadieno-estireno reforçados com 10 e 20% (m/m) de fibras de polpa celulose branqueada não modificadas (FNT) e modificadas com nanopartículas de sílica (FT1 e FT2) foram obtidos por extrusão e posteriormente por injeção, depois os compósitos foram caracterizados quanto à densidade, análise térmica (TGA/DTG), temperatura de deflexão térmica (HDT) e a temperatura de amolecimento VICAT. A adição de fibras, de modo geral, proporcionou incremento para a temperatura de deflexão térmica HDT e temperatura de amolecimento VICAT, sendo mais acentuado quando o teor de fibras passou de 10% para 20%. No entanto, o aumento do teor de fibras de 10% para 20%, em comparação ao ABS puro provocou diminuição da temperatura de início de degradação e provocou aumento da densidade.

ABSTRACT The aim of this study was to evaluate thermal properties of composites made with terpolymer acrylonitrile-butadiene-styrene (ABS) reinforced with silica nanoparticles (SiO2) modified cellulose. Primarily, the fibers were modified using the sol-gel process and the tetraethyl ortosilicate (TEOS) as precursor. In addition, two concentrations of TEOS and two reaction times were used to produce two types of modified fibers, FT1 and FT2 fibers, then was determined the yield of modification process. The fibers were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and its derivative (DTG). The acrylonitrile-butadiene-styrene composites reinforced with 10 and 20% (w/w) unmodified cellulose pulp fibers (FNT) and silica nanoparticles modified (FT1 and FT2) were obtained by extrusion process and subsequent injection. The composites were characterized in terms of density, thermogravimetric (TGA / DTG), thermal deflection temperature (HDT) and VICAT softening temperature. In general, the addition of fibers provided an increase for HDT and VICAT, being more pronounced when the fiber content increased from 10% to 20%. However, in comparison with ABS the increasing of fiber content from 10% to 20%, caused a decrease in Tonset and caused an increase in density.

RESUMO O poliestireno expandido (EPS) é um polímero reciclável amplamente utilizado na fabricação de embalagens para isolamento acústico, proteção de bens de consumo duráveis e na indústria da construção civil. O PS é facilmente reciclável com o aumento da temperatura, podendo dar origem a novos materiais. Entretanto suas propriedades térmicas podem ser afetadas, principalmente se acrescidos de fibras naturais. Diante desse contexto, esse trabalho tem como objetivo estudar as propriedades térmicas dos compósitos de poliestireno reciclado reforçados com fibra de celulose do bagaço de cana-de-açúcar. Os compósitos de PS reciclados contendo 10 e 20% (m/m) de celulose de bagaço foram obtidos por extrusão e caracterizados por análise térmica: Análise Termogravimétrica (TGA), Calorimetria Exploratória Diferencial (DSC), Análise Dinâmico-Mecânica (DMA) e Temperatura de Deflexão Térmica (HDT). Os resultados mostraram que as fibras ricas em lignina residual atuaram como reforço melhorando a rigidez do material com a adição das fibras, bem como promoveram o aumento da temperatura de deflexão térmica. Já a estabilidade térmica dos compósitos é intermediária entre a fibra e matriz, diminuindo com o aumento do teor de fibras. Portanto, conclui-se que a utilização de EPS como matriz na obtenção de compósitos reforçados com fibras naturais é viável e sugere o uso deste resíduo como uma excelente alternativa para o setor de reciclagem.

ABSTRACT Expanded polystyrene (EPS) is a recyclable polymer widely used in the manufacture of packaging for acoustic insulation, protection of durable consumer goods and in the construction industry. The PS is easily recyclable with increasing temperature, giving new materials. However, thermal properties can be affected, mainly if added of natural fibers. In this context, this work objective to study the thermal properties of recycled polystyrene composites reinforced with cellulose fibers from sugarcane bagasse. The recycled composites of PS reinforced 10 and 20 wt% cellulose bagasse were obtained by extrusion, and characterized by thermal analysis thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and heat deflection temperature (HDT). The results showed that the fibers rich in residual lignin act as reinforcement improving the stiffness of the material with the addition of the fibers, as well as promoted the increase of the heat deflection temperature for the composites. The thermal stability of the composites is intermediate between the fiber and matrix, decreasing with the increase of fibers content. Therefore, it is concluded that the use of EPS as a matrix in the obtainment composites reinforced with natural fibers is viable and suggest the use of this residue as an excellent alternative for the recycling industry.

The present work aimed to study sugarcane bagasse fibers pre-treated with fungi and using NaOH/ anthraquinone (AQ) in chemical pulping processes for applications in composite materials. Bagasse was decayed with 250 mg of Ceriporiopsis subvermispora inoculum in a 20 L bioreactor. After that, samples were submitted to similar conditions of decaying without inoculum charge. Decayed and undecayed fibers were treated with NaOH 12.5 wt%, 0.15 of AQ and a 12:1 (v/w) liquor:bagasse ratio at 160°C. Then, all obtained fibers were characterized according to their chemical composition. Dried biotreated (decayed) and control (undecayed) fibers were mixed through an extruder process with polypropylene. Later, composite granulates were injected directly in mold with cavities for tensile, flexural and shear tests. Composite materials with 10 and 20 wt% fibers were submitted to static mechanical standard tests and DMA (Dynamic Mechanical Analysis) to evaluate the effect of biotreatment. Biotreatment, cook time (pulping), and fiber content contributed to improvements in the mechanical properties of the composites. The interface between fiber and matrix was increased with the biotreatment and pulping of fibers. Furthermore, DMA results also showed that fiber incorporation into PP improved the modulus, mainly for biotreated fibers/PP composites. The Tg (tan δ data) from composites was dislocated at lower temperatures with respect to neat PP due to the influence of fibers on matrix.

Mechanical recycling is utilized to reuse waste and obtain other plastic products via the reprocessing of a material in industrial equipment. Natural fiber composites have become more popular in recent years; however, these composites' mechanical behavior remains less well-understood than single polymers’ behavior after recycling. Therefore, the objective of this work was to study the degradation of different sugarcane fibers/polypropylene composites using new grinding and injection processes and to evaluate the mechanical properties of these materials using analysis of variance (ANOVA). This work reveals the mechanical behaviors of recycled natural fiber composites that contain thermal stabilizer additives. Polypropylene composites reinforced with differently treated bagasse and straw fibers (10 and 20 wt%/PP) were obtained through melt mixing using a high-intensity thermokinetic mixer and were subsequently injected. The recycled composites exhibited decreased tensile strength relative to the original composites. However, when thermal stabilizers were added, the mechanical properties were maintained or increased, depending on the fiber and additive types.