High-density polyethylene (HDPE) reinforced with cellulose from rice husk (RH) were prepared and studied. The RH biomass was submitted to acid extraction and bleaching process and then analyzed for its cellulose extraction efficiency by X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR). After that, the RH cellulose (RHC) was incorpored to the HDPE matrix by melt blending with different filler contents (5, 10 and 15 wt%), and then characterized in terms of mechanical properties and morphology. The RHC incorporation in the HDPE matrix resulted in an increase in elastic modulus regardless the filler content added; also, the impact resistance was maintained for RHC contents up to 10%. The morphological analysis of the composites showed that the cellulose was well dispersed in the matrix, which contributed to the improvement of the final rigidity of these materials, indicating the feasibility of incorporating this residue in the production of HDPE composites.
Bentonite clay is surface modified and incorporated into PC/ABS (70/30) polymer blend by melt mixing in concentrations of 1, 3 and 5 wt% of clay. The efficiency of the treatments is analyzed by Fourier transform infrared spectroscopy (FTIR), x‐ray fluorescence (XRF) and x‐ray diffraction (XRD). Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) are used to evaluate the blends miscibility and morphology, respectively, and the mechanical behavior is analyzed by tensile tests. The methodologies used are efficient to modify the clay's surface. DSC and SEM showed that the blend remained immiscible with the addition of the fillers. The mechanical test showed an increase in the Young's modulus of the nanocomposite with addition of 1 wt% of the natural clay and a modification in the fracture behavior of the blend, from ductile to brittle, when 3 and 5 wt% of the organophilized clay are used.
This work provides a study about the incorporation of a high density polyethylene (HDPE) matrix composite in medium density fiberboards (MDF). A composite was processed in a single screw extruder with 5% of Pinus spp fibers in a HDPE matrix and applied as reinforcing agent in MDFs, as well as pure HDPE, in 11 different variations, using 12% of urea-formaldehyde resin and nominal density of 750 kg.m−3. The composite and the pure HDPE were analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The DSC results showed that both polymeric matrix and composite presented the same melting temperature but the composite had a reduced melting enthalpy and crystallinity due to thermal history. SEM analysis showed a well distribution of fibers on the composite. The results of technological properties of MDFs were compared to commercial MDF standards. The MDF reinforced with 40% of polymeric composite reached all minimum standard requirements, being the most recommended to be used as an alternative to conventional MDF, in terms of physical and mechanical performance.
A organofilização de argilas bentonitas com sal quaternário de amônio foi avaliada como meio de se obter nanopartículas de argila atuando como reforço em nanocompósitos com matriz de policarbonato/poli(acrilonitrila-butadieno-estireno). A caracterização por difração de raios-x da argila organofilizada mostra um aumento no espaçamento basal da montmorilonita quando comparada a argila natural. Os espectros de espectroscopia de infravermelho com transformada de Fourrier confirmaram a troca dos cátions inorgânicos da argila natural pelos cátions orgânicos de amônio do modificador orgânico. Os nanocompósitos foram preparados por mistura no estado fundido em uma extrusora monorosca. Os resultados mostraram um aumento de 49% na resistência ao impacto com a adição de 1% em massa de argila organofílica nos nanocompósitos quando comparado a blenda sem reforço. Imagens obtidas por microscopia eletrônica de varredura mostraram um refinamento na morfologia co-contínua da blenda policarbonato/acrilonitrila-butadieno-estireno com a adição de 1% em massa de argila organofílica.
Argila bentonita natural e após modificações superficiais, foram testadas como adsorventes do corante Rodamina B para fins de comparação de eficiência dos tratamentos na remoção do corante. As modificações realizadas na argila foram: organofilização em solução, feita através da intercalação do sal quaternário cloreto de cetil trimetil amônio, organofilização no estado sólido pela intercalação do sal cetil trimetil amônio e tratamento ácido, feito com ácido clorídrico. Soluções de corante na concentração de 10 mg/L para pH diferentes (3,4,9,12) foram feitas e posteriormente as agilas foram dispersas nessas soluções na concentração de 0,4 g/L, sendo o sistema mantido sob agitação manual. Alíquotas em diferentes tempos (10, 20 e 30 min) foram retiradas e levadas para análise de espectrofotometria no UV-Visível, onde pode-se avaliar a variação de corante nas soluções que estiveram em contato com as argilas. As argilas que tiveram contato com a argila ácida foram as que obtiveram melhor resultado de remoção de corante, exceto para o pH 12 onde a argila natural foi mais eficiente. As modificações com sais quaternários não tiveram bons resultados mostrando que não são metodologias adequadas para modificação de adsorventes do corante Rodamina B.
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