Resumo: Espumas poliméricas são materiais bifásicos constituídos por uma matriz polimérica sólida e por uma fase gasosa proveniente de um agente de expansão. Produtos obtidos com estes materiais vêm ganhando bastante espaço no mercado por apresentar boas propriedades mecânicas aliadas à baixa densidade e baixo custo. O uso de EVA com elastômeros tem sido uma alternativa para proporcionar propriedades mais nobres a esses compostos expansíveis. Dentre os elastômeros utilizados, o EPDM apresenta um potencial de aplicação elevado por apresentar boa compatibilidade com as poliolefinas. Como na fabricação da espuma tem-se simultaneamente reações de reticulação e de formação gases de expansão, o balanço desses efeitos tem forte influência sobre as características físicas do produto. Neste estudo, avaliou-se o efeito de um agente reticulante nas formulações de espumas de EVA/EPDM. As propriedades físico-mecânicas, reométricas e morfológicas de misturas EVA/EPDM com diversas proporções de peróxido de dicumila, utilizado como agente de reticulação, foram avaliadas. Os resultados mostraram que o teor de reticulante apresenta forte influência nas características técnicas das espumas obtidas. Palavras-chave: Espumas poliméricas, EVA, EPDM, agente de reticulação, propriedades físico-mecânicas. The Effect of a Crosslinking Agent on the Morphology and Physical and Mechanical Properties of Polymer Foams Based on EVA and EPDMAbstract: Polymer foams are biphasic materials prepared with a polymer matrix and a gaseous phase from a foaming agent. Products based on this type of material are currently in a good market position due to the good mechanical properties, low density and competitive cost. Blending EVA with elastomers is a feasible alternative to enhance the properties of the expandable compounds. Among the elastomers used as a blend component with EVA, EPDM has a high potential since it has a good compatibility with polyolefins. Considering that during the foam processing there are simultaneous crosslinking reactions and the formation of gases, the balance between these two effects has a strong influence over the physical characteristics of the final product. In this study the effect of a crosslinking agent on EVA/ EPDM foams was investigated. The physical, mechanical and rheometric properties, as well as the foam morphology, were analyzed as a function of dicumil peroxide, used as a crosslinking agent. The results showed that this additive has a strong influence in the crooking and expansion of the compounds, affecting their properties. Keywords: Polymer foam, EVA, EPDM, crosslinking agent, physical and mechanical properties. IntroduçãoEspumas poliméricas, plásticos celulares ou plásticos expandidos podem ser definidos como materiais constituídos por uma fase sólida de uma matriz polimérica e por uma fase gasosa derivada de um agente expansor [1,2] . Embora existam também espumas rígidas, a maioria dos produtos comerciais são flexíveis e bastante utilizados em aplicações onde se requerem propriedades de absorção de impacto e...

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Featured Application: The development of advance construction materials based on waste valorisation is a reality. The cement-based mortar with recycled metallic waste presented in this study could be potentially used as a building material with crack self-monitoring properties.Abstract: This paper investigates the influence of the type and amount of recycled metallic waste on the physical and mechanical properties of cement-based mortars. The physical and mechanical properties of cement mortars, containing four different amounts of metallic waste (ranged 4 to 16% by cement weight), were evaluated by measuring the bulk density, total porosity, flexural and compressive resistance, and dynamic elastic modulus by ultrasonic tests. All the properties were measured on test specimens under two curing ages: 7 and 28 days. Additionally, the morphological properties and elemental composition of the cement and metallic waste were evaluated by using Scanning Electron Microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS), and X-ray fluorescence (XRF). Main results showed that the addition of metallic waste reduced the bulk density and increased the porosity of the cement-based mortars. Furthermore, it was observed that flexural and compressive strength proportionally increased with the metallic waste addition. Likewise, it was proven that elastic modulus, obtained by compressive and ultrasonic tests, increases with the metallic waste amount. Finally, based on a probability analysis, it was confirmed that the addition of metallic waste did not present a significant effect on the mechanical performance of the cement-based mortars.