The understanding of atomic and electronic structures is crucial for designing devices. The surface properties of bimetallic systems have been widely studied due to the possibility of applications in different areas, such as catalysis, magnetism, microelectronics and electrochemistry. The objective of this work is studying thin (10 nm) Pd and Ni films on polycrystalline Ni and Pd substrates (Pd/Ni and Ni/Pd), respectively, grown by dc magnetron sputtering. The film structure was investigated by x-ray diffraction (XRD), morphology, by atomic force microscopy and surface composition, and by x-ray photoelectron spectroscopy. The XRD indicated that the Ni/Pd film did not present an ordered structure, while the Pd/Ni had a nanocrystalline structure with a slight structural distortion. Oxide formation was detected for the Ni film, but not for the Pd film.

Resumo: Devido a suas excelentes propriedades mecânicas o polietileno linear de baixa densidade, PELBD, tem ganhado cada vez mais importância na indústria de embalagens. Essas propriedades são resultado de sua estrutura molecular, da existência de ramificações curtas, SCB, e da distribuição dessas ramificações, DSCB. Junto com o peso molecular, PM, e sua distribuição, DPM, as ramificações curtas também afetam o processo de sopro de filmes influenciando na solidificação do filme até a linha de neve, já que a cinética de cristalização é dependente da distribuição destas ramificações. Assim, este trabalho teve como objetivo verificar a influência da DSCB do PELBD nas propriedades reológicas e óticas de filmes tubulares. Para isso, três PELBD foram escolhidos; dois sintetizados com catalisador Ziegler-Natta e um com catalisador metaloceno, de peso molecular ponderal médio, M w , similar e DSCB diferentes.Observou-se que a DSCB exerce influência nas propriedades reológicas que refletem a elasticidade do material como a primeira diferença de tensões normais N 1 , o módulo de armazenamento G'(ω), e a deformação recuperável γ r ; entretanto na viscosidade em função da taxa de cisalhamento η( ), e no módulo de perda G"(ω), a diferença nessa distribuição não foi percebida. Observou-se também que quanto maior a deformação recuperável dos PELBD, menores foram as estruturas cristalinas formadas o que diminuiu a opacidade dos filmes. Porém essa proporcionalidade manteve-se até uma determinada γ r mínima, acima da qual a fratura do fundido se sobrepôs à recuperação da deformação e a opacidade voltou a aumentar. Palavras-chave: Polietileno linear de baixa densidade, filmes soprados, deformação recuperável, opacidade. Correlation Between Rheological and Optical Properties of LLDPE Blown Films with Different Distributions of Short Chain BranchingAbstract: Linear low-density polyethylene, LLDPE, has increased its market share in the packaging industry due to its excellent mechanical properties. These properties are the result of its molecular structure due to its short chain branching, SCB, and their distribution, DSCB. Together with the molecular weight and the distribution of molecular weights, the SCB affects the blown film process because it interferes in the film solidification and crystallization kinetics up to the freezing line. The objective of this work was to verify the influence of the DSCB of LLDPE in the rheological and optical properties of blown films. Three LLDPE, synthesized with Ziegler-Natta and metallocene catalysts, were studied, all with similar weight average molecular weight, M w , but with different DSCB. It was observed that the DSCB influenced the rheological properties that reflect the material elasticity, such as the first normal tension difference, N 1 ( ), the storage modulus G'(w) and the recoverable strain γ r ; however, the rheological properties that reflect the viscosity, such as the shear viscosity η( ) and the loss modulus G"(w), were not affected. In addition, the higher the γ r of the LLDPE,...

The surface properties of bimetallic systems have been studied recently due to possible applications in different areas, such as electrochemistry, magnetism, and catalysis. Understanding of the atomic and electronic structures is crucial for designing metallic devices. In this work, thin films of gold and copper were grown on a polycrystalline palladium substrate by sputtering. For both films, the thickness was estimated to be 10 nm. The morphology of the films was investigated by atomic force microscopy (AFM). XPS was employed in order to verify the possibility of alloy formation. Oxide formation was observed for the Cu film, but not for the Au film. The copper oxide (CuO) was removed by argon ion sputtering. Alloying was not observed in the Au/Pd or Cu/Pd films.

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