The practice of recycling over the years has been increasingly encouraged, with the aim being the manufacturing of materials that contribute to sustainable development. In light of this, the present work evaluated the potential of mixtures of polystyrene (PS)/recycled copolymer polypropylene (PPr), using styrene-(ethylene/butylene)-styrene (SEBS) as a compatibilizing agent. Initially, the mixtures were prepared in a co-rotational twin-screw extruder, and, afterwards, the extruded granules were molded by injection. The properties of torque rheometry, impact strength, tensile properties, differential scanning calorimetry (DSC), heat deflection temperature (HDT), and scanning electron microscopy (SEM) were evaluated. The formulation PS/PPr/SEBS (70/20/10 %wt.) demonstrated an increase in viscosity, corroborating with an increase of 123% and 227% in the elongation at break and impact strength, respectively, compared to neat PS. Though the elastic modulus and tensile strength suffered losses, the reduction was not drastic. Furthermore, the addition of a semi-crystalline recycled material in the amorphous matrix (PS) contributed to an increase in thermomechanical strength, as seen in the HDT. The morphology revealed that SEBS is effective in making PS/PPr mixtures compatible because the dispersed phase is well adhered to the PS matrix and promotes greater morphological stability. Thus, it is possible to add value to discarded material and reduce the costs of the final product, which can reduce pollution.

The development of new ecological materials to promote sustainability is being encouraged. Crosslinked biopolyethylene (BioPE)/noni flour (Morinda citrifolia) biocomposites were prepared using maleic anhydride-grafted polyethylene (PE-g-MA) and dicumyl peroxide (DCP). The biocomposites were processed in an internal mixer and injection molded. Torque rheometry, Izod impact strength, tensile strength, heat deflection temperature (HDT), differential scanning calorimetry (DSC), thermogravimetry (TG), and scanning electron microscopy (SEM) properties were investigated. Torque rheometry curves suggest that the biocomposites did crosslink due to the DCP attack on the BioPE chain. The BioPE/noni flour/PE-g-MA formulation with 0.5% and 1% DCP produced a higher level of crosslinking. As a result, the mechanical properties (impact strength, elastic modulus, and tensile strength) were improved. SEM showed fractured noni flour particles in the BioPE matrix with the formation of a tubular structure. The HDT increased, suggesting that the biocomposites exhibit enhanced thermomechanical strength. Furthermore, the biocomposites thermal properties obtained by DSC underwent few modifications. The TG results showed that the crosslinked biocomposites have better thermal stability than the noncrosslinked biocomposites. The crosslinking process of BioPE/noni flour biocomposites with the PE-g-MA/DCP hybrid is an effective way to improve the performance of these materials.

Carbon fiber (CF) is a difficult material to recycle, generating accumulation and environmental impacts when disposed of incorrectly. The practice of reuse is being encouraged, aiming to minimize socio-environmental impacts. The present research aimed to develop polypropylene (PP) composites with CF waste, using styrene-(ethylene-butylene)-styrene grafted with maleic anhydride (SEBS-MA) and ethylene-propylene-diene grafted with maleic anhydride (EPDM-MA), as compatibilizers. The composites were processed in a mixer and injection molded. The addition of the CF in the PP matrix did not hinder processability, as verified in torque rheometry. Significant increases were achieved in impact strength and elongation at break, especially in the PP/FC/ SEBS-MA and PP/FC/EPDM-MA composites. Incorporating 15% EPDM-MA reduced the elastic modulus and tensile strength by 23% and 32%, while SEBS-MA by 13% and 23%, relative to PP, respectively, due to the increase in flexibility of the composites. When the PP/FC composites were compatibilized with SEBS-MA and EPDM-MA, there was a higher level of interaction among the phases, generating a higher wettability, as verified in the scanning electron microscopy. Such behavior was important to increase the crystallinity of the compatibilized composites. The composites thermal stability increased significantly, increasing in 40 C, compared to pure PP. In general, the compatibilization with SEBS-MA was more effective, generating better properties.As a consequence, the heat deflection temperature of the composites remained the same as the level of pure PP, suggesting good structural stability. The results are valuable for the recycling area, since CF can be reused as a polymer additive to improve properties.

No abstract

Blendas de poliamida 6 (PA6) com poliestireno de alto impacto (HIPS) foram preparadas, utilizando-se o copolímero de estireno-(etileno-butileno)-estireno enxertado de anidrido maleico (SEBS-MA), como agente compatibilizante. As blendas foram preparadas em uma extrusora de rosca dupla corrotacional e, posteriormente, moldadas por injeção. As propriedades de reometria de torque, resistência ao impacto Izod, temperatura de deflexão térmica (HDT) e microscopia eletrônica de varredura (MEV) foram investigadas. Os resultados mostraram que houve um aumento no torque das blendas de PA6/HIPS com a adição do compatibilizante SEBS-MA. A resistência ao impacto e a HDT aumentaram 56% e 24,5 % em comparação com a PA6 pura, quando a formulação da blenda PA6/HIPS contém 15 pcr de SEBS-MA. Essa blenda apresentou uma maior estabilidade na morfologia, conforme verificado no MEV, com melhor adesão interfacial e menor quantidade de vazios, resultando principalmente na maior resistência ao impacto. Em geral, as propriedades de resistência ao impacto e HDT da PA6 podem ser adaptadas e aprimoradas por meio do desenvolvimento de blendas poliméricas.