RESUMO
For the purpose of renewable materials applications, Curauá fiber treated with 5% sodium hydroxide was added to high-density biopolyethylene, using an entirely Brazilian raw material of sugarcane ethanol. Polyethylene grafted with maleic anhydride was used as a compatibilizer. With the addition of curauá fiber, the crystallinity was reduced, possibly due to interactions in the crystalline matrix. A positive thermal resistance effect was observed for the maximum degradation temperatures of the biocomposites. When curauá fiber was added (5% by weight), the morphology showed interfacial adhesion, greater energy storage and damping capacity. Although curauá fiber additions did not affect the yield strength of high-density bio polyethylene, its fracture toughness improved. With the addition of curauá fiber (5% by weight), the fracture strain was greatly reduced to about 52%, the impact strength was also reduced, suggesting a reinforcing effect. Concomitantly, the modulus and the maximum bending stress, as well as the Shore D hardness of the curauá fiber biocomposites (at 3 and 5% by weight), were improved. Two important aspects of product viability were achieved. First, there was no change in processability and, second, with the addition of small amounts of curauá fiber, there was a gain in the specific properties of the biopolymer. The resulting synergies can help ensure more sustainable and environmentally friendly manufacturing of automotive products.
RESUMO
Hydrogels are a very useful type of polymeric material in several economic sectors, acquiring great importance due to their potential applications; however, this type of material, similarly to all polymers, is susceptible to degradation, which must be studied to improve its use. In this sense, the present work shows the degradation phenomena of commercial hydrogels based on potassium and sodium polyacrylate caused by the intrinsic content of different types of potable waters and aqueous solutions. In this way, a methodology for the analysis of this type of phenomenon is presented, facilitating the understanding of this type of degradation phenomenon. In this context, the hydrogels were characterized through swelling and FTIR to verify their performance and their structural changes. Likewise, the waters and wastewaters used for the swelling process were characterized by turbidity, pH, hardness, metals, total dissolved solids, electrical conductivity, DLS, Z-potential, and UV-vis to determine the changes generated in the types of waters caused by polymeric degradation and which are the most relevant variables in the degradation of the studied materials. The results obtained suggest a polymeric degradation reducing the swelling capacity and the useful life of the hydrogel; in addition, significant physicochemical changes such as the emergence of polymeric nanoparticles are observed in some types of analyzed waters.
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Polymeric wastes have caused increasing environmental problems, mainly in oceans that accumulate large amounts of non-degradable plastic waste. Particularly, waste of polymeric multilayer films for packaging presents low interest for mechanical recycling due to the poor properties and low commercial value of the recycled material generated as polymeric blends. Multilayer films of low-density polyethylene (LDPE) and polyamide 6 (PA6) is a typical material used for packaging applications. The aim of this study was to evaluate the action of the concentration of maleic anhydride grafted polyethylene (PE- g-MA) on the compatibilization of LDPE/PA6 blends generated from mechanical recycling of multilayer films containing both polymers. The action of the PE- g-MA on the properties of the LDPE/PA6 blends was evaluated by tensile tests, optical microscopy, melt flow rate, and scanning electron microscopy. The use of PE- g-MA at 2.5 wt% as a compatibilizer during reactive extrusion of the multilayer films waste has showed the best result for production of the respective recycled LDPE/PA6 blends.
Assuntos
Caprolactama , Polietileno , Caprolactama/análogos & derivados , Polímeros , ReciclagemRESUMO
Introducción: En pacientes con el polimorfismo del receptor plaquetario IIIa (PIA2), más en homocigotos PIA2/A2, se observó un porcentaje mayor de reestenosis postangioplastia coronaria con stent que en los pacientes PIA1/A1 o normales. Objetivo: Determinar la presencia del alelo polimórfico PIA2 en pacientes con reestenosis postangioplastia con stent en una población argentina; evaluar porcentaje de PIA2/A2 entre los reestenosadores y determinar la penetrancia del alelo polimórfico PIA2 en una población de nuestro país sin antecedentes coronarios. Métodos: Se evaluaron 45 pacientes, que integraron tres poblaciones. Díez sin antecedentes coronarios (9 hombres, 30 ± 5 años). Dieciseis pacientes con angioplastia (13 hombres, 62 ± 11 años) con control angiográfico a los 7 ± 1 mes que no evidenció reestenosis y 19 con reestenosis postangioplastia (16 hombres, 60 ± 12 años). Se consideró reestenosis una lesión mayor del 50 por ciento en el reestudio. Se realizó la reacción en cadena de la polimerasa en busca de la presencia del alelo PIA2. Se utilizó la prueba de Fischer para comparaciones. Resultados: De los 19 pacientes reestenosadores, 9 presentaron el alelo A2 (47 por ciento); de los 16 pacientes no reestenosadores presentaron el alelo A2 sólo el 13 por ciento (p < 0,04). De los 10 pacientes sin antecedentes se detectó un solo A2 (10 por ciento). Sólo 2 pacientes eran homocigotos A2/A2 y se encontraron en el grupo reestenosador. Conclusión: La presencia del alelo A2 (PIA1/A2 o PIA2/A2) fue significativamente mayor en los pacientes con reestenosis, lo cual podría ser un predictor de reestenosis postangioplastia con stent y su detección previa podría tener implicaciones terapéuticas. (AU)
Assuntos
Humanos , Masculino , Reestenose Coronária , Polimorfismo Genético , Antígenos de Plaquetas Humanas/genética , Integrina beta3/genética , DNA/análise , Stents , Fatores de Risco , Argentina/epidemiologiaRESUMO
Introducción: En pacientes con el polimorfismo del receptor plaquetario IIIa (PIA2), más en homocigotos PIA2/A2, se observó un porcentaje mayor de reestenosis postangioplastia coronaria con stent que en los pacientes PIA1/A1 o normales. Objetivo: Determinar la presencia del alelo polimórfico PIA2 en pacientes con reestenosis postangioplastia con stent en una población argentina; evaluar porcentaje de PIA2/A2 entre los reestenosadores y determinar la penetrancia del alelo polimórfico PIA2 en una población de nuestro país sin antecedentes coronarios. Métodos: Se evaluaron 45 pacientes, que integraron tres poblaciones. Díez sin antecedentes coronarios (9 hombres, 30 ± 5 años). Dieciseis pacientes con angioplastia (13 hombres, 62 ± 11 años) con control angiográfico a los 7 ± 1 mes que no evidenció reestenosis y 19 con reestenosis postangioplastia (16 hombres, 60 ± 12 años). Se consideró reestenosis una lesión mayor del 50 por ciento en el reestudio. Se realizó la reacción en cadena de la polimerasa en busca de la presencia del alelo PIA2. Se utilizó la prueba de Fischer para comparaciones. Resultados: De los 19 pacientes reestenosadores, 9 presentaron el alelo A2 (47 por ciento); de los 16 pacientes no reestenosadores presentaron el alelo A2 sólo el 13 por ciento (p < 0,04). De los 10 pacientes sin antecedentes se detectó un solo A2 (10 por ciento). Sólo 2 pacientes eran homocigotos A2/A2 y se encontraron en el grupo reestenosador. Conclusión: La presencia del alelo A2 (PIA1/A2 o PIA2/A2) fue significativamente mayor en los pacientes con reestenosis, lo cual podría ser un predictor de reestenosis postangioplastia con stent y su detección previa podría tener implicaciones terapéuticas.