ABSTRACT:The effect of different mixing protocols in the preparation of PA6/ABS/MMA-MA (57.5/37.5/5 wt %) blends on their morphological, rheological, thermal, thermomechanical, and mechanical behavior were studied. Despite the second-phase size reduction due to copolymer incorporation, mixing sequence seems to play an important role in the properties of the blends. When PA6 is blended with the pre-blended ABS/MMA-MA system, compatibilizer is preferentially located in ABS phase and a co-continuous structure is formed. The co-continuity is believed to be responsible for the enhancements in toughness, but excessive presence of MMA-MA in ABS phase seems to hamper thermomechanical properties. On the other hand, when ABS is blended with the PA6/MMA-MA system previously prepared, compatibilizer is preferentially located in PA6 phase and a particle-in-matrix morphology is observed. The absence of excessive amount of MMA-MA in ABS phase avoids the negative effect on thermomechanical resistance, however enhancements in toughness are not so pronounced.

Structural color is frequently exploited by living organisms for biological functions and has also been translated into synthetic materials as a more durable and less hazardous alternative to conventional pigments. Additive manufacturing approaches were recently exploited for the fabrication of exquisite photonic objects, but the angle-dependence observed limits a broader application of structural color in synthetic systems. Here, we propose a manufacturing platform for the 3D printing of complex-shaped objects that display isotropic structural color generated from photonic colloidal glasses. Structurally colored objects are printed from aqueous colloidal inks containing monodisperse silica particles, carbon black, and a gel-forming copolymer. Rheology and Small-Angle-X-Ray-Scattering measurements are performed to identify the processing conditions leading to printed objects with tunable structural colors. Multimaterial printing is eventually used to create complex-shaped objects with multiple structural colors using silica and carbon as abundant and sustainable building blocks.

The effect of maleic anhydride (MA) content on morphological, thermal, thermomechanical and mechanical properties of PA6/AES/MMA-MA (66.5/28.5/5 wt%) system was investigated. In general, the simple incorporation of MMA-MA to PA6/AES system is responsible for enhancements in mechanical performance. PA6/AES/MMA-MA3% and PA6/AES/MMA5% exhibited similar morphology and final properties, indicating no MA content effect on the studied system. On the other hand, PA6/AES/ MMA-MA10% exhibited a quite different morphology and lower mechanical performance compared to the other compatibilized blends. Such unexpected behavior was not attributed to the effective maleic anhydride content in this composition, but to the reduced molar mass resulted from the excess of nonreacted MA monomer during the synthesis procedure.

We report on genosensors to detect an ssDNA sequence from the SARS-CoV-2 genome, which mimics the GU280 gp10 gene (coding the viral nucleocapsid phosphoprotein), using four distinct principles of detection...

The effect of organoclay incorporation and four different blending protocols on morphological, rheological, thermal, thermomechanical, and mechanical properties of PA6/ABS/SANMA/OMMT (55.0/35.0/5.0/5.0 wt%) nanocomposites was evaluated. As expected, even only with minor amounts of clay loading, significant reinforcement effect on mechanical and thermomechanical properties was achieved. Despite the morphological and structural similarities between studied compositions, it was found that mixing sequence might have great influence in mechanical properties, particularly in toughness. It is supposed that compatibilizing process though in situ reactions is much more efficient when PA6, ABS and SANMA are blended in the same extrusion step. Otherwise, when such condition is not satisfied, PA6/OMMT interactions seems to hamper the compatibilizing effect of SANMA, leading to inferior impact strength.

ResumoO efeito da organofilização da argila no comportamento mecânico, morfológico e termo-mecânico de nanocompósitos baseados em blendas de poliamida 6 )/acrilonitrila-EPDM-estireno foi estudado. Três nanoargilas foram utilizadas para a preparação dos nanocompósitos: duas montmorilonitas comerciais modificadas organicamente (Cloisite  30B and Cloisite  20A) e uma montmorilonita sódica não modificada (Cloisite  Na + ). Difração de raios-X em alto ângulo, microscopia eletrônica de transmissão e testes de tração e resistência ao impacto foram utilizados para avaliar o efeito da organofilização da nanoargila na morfologia e propriedades mecânicas dos materiais. As propriedades termo-mecânicas foram avaliadas por análise dinâmico mecânica e temperatura de deflexão térmica. Os resultados mostraram que a modificação da nanocarga afeta simultaneamente o grau de reforço da matriz, dispersão das lamelas de argila na blenda e tamanho da fase dispersa AES. A adição das diferentes nanoargilas aumenta o módulo elástico de todos os nanocompósitos ternários em relação à blenda pura sem argila. Por outro lado, um aumento na tenacidade foi obtido apenas para os sistemas com Cloisite  Na + . Um aumento significativo no módulo de armazenamento e HDT foi observado pela incorporação da Cloisite  30B na blenda. Palavras-chave: organofilização, nanocompósitos, blendas, nanoargilas. AbstractThe effect of clay organophilization on mechanical, morphological and thermo-mechanical behavior of polyamide-6/acrylonitrile-EPDM (ethylene/propylene/diene elastomer)-styrene blends was studied. Three nanoclays were used for the preparation of nanocomposites: two commercial organically modified montmorillonites (Cloisite  30B and Cloisite  20A) and an unmodified sodium montmorillonite (Cloisite  Na + ). We used wide angle X-ray scattering, transmission electron microscopy and mechanical tests to evaluate the effect of clay modification on the morphology and mechanical properties of the nanocomposites. The thermo-mechanical properties were characterized using dynamic mechanical analysis and heat distortion temperature (HDT). The results show that the modification of clay affected simultaneously the degree of PA6 matrix reinforcement, dispersion of the clay lamellas in the blend and size of the dispersed phase AES. The incorporation of different nanoclays increase the elastic modulus of all the ternary nanocomposites compared to the neat blend. An increase in the toughness is obtained only for systems with Cloisite  Na + . A significant increment in the storages modulus and HDT was observed by the incorporation of Cloisite  30B in the PA6/AES blends.

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