The structure of carbon nanotubes in a polymer matrix

We carried out an analytical structural analysis of interfacial effects and differences in the reinforcing ability of carbon nanotubes for polydicyclopentadiene/carbon nanotube nanocomposites with elastomeric and glassy matrices. In general, it showed that the reinforcing (strengthening) element of the structure of polymer nanocomposites is a combination of the nanofiller and interfacial regions. In the polymer matrix of the nanocomposite, carbon nanotubes form ring-like structures. Their radius depends heavily on the volume content of the nanofiller. Therefore, the structural reinforcing element of polymer/carbon nanotube nanocomposites can be considered as ring-like formations of carbon nanotubes coated with an interfacial layer. Their structure and properties differ from the characteristics of the bulk polymer matrix.According to this definition, the effective radius of the ring-like formations increases by the thickness of the interfacial layer. In turn, the level of interfacial adhesion between the polymer matrix and the nanofiller is uniquely determined by the radius of the specified carbon nanotube formations. For the considered nanocomposites, the elastomeric matrix has a higher degree of reinforcement compared to the glassy matrix, due to the thicker interfacial layer. It was shown that the ring-like nanotube formations could be successfully modelled as a structural analogue of macromolecular coils of branched polymers. This makes it possible to assess the effective (true) level of anisotropy of this nanofiller in the polymer matrixof the nanocomposite. When the nanofiller content is constant, this level, characterised by the aspect ratio of the nanotubes, uniquely determines the degree of reinforcement of the nanocomposites

SOCIABILIDADE E JUVENTUDE RURAL: A FESTA JUNINA COMO ELEMENTO FORTALECEDOR DA CULTURA JUVENIL DO CAMPO (SOCIABILITY AND RURAL YOUTH: THE JUNE PARTY (FESTA JUNINA) AS A STRENGTHENING ELEMENT OF THE JUVENILE CULTURE IN RURAL AREAS)

RESUMO:Neste artigo, compartilhamos dados de pesquisa realizada no Assentamento de Reforma Agrária Bela Vista do Chibarro, localizado em Araraquara, São Paulo, cujo objetivo foi desenvolver análises acerca da sociabilidade entre jovens no meio rural, por meio de suas experiências com festividades, dentre elas, a Festa Junina. Para tanto, apresentamos relatos de doze jovens do sexo feminino com idade entre 12 e 16 anos que moram naquela localidade. A pesquisa revela que as práticas de sociabilidade são importantes para as jovens quando, nessas práticas, encontram oportunidade de celebrar o ciclo da vida na qual estão inseridas, considerando que sua juventude é permeada por proibições. Constatamos que a Festa Junina na comunidade surge como um elemento de fortalecimento da identidade e do pertencimento, sobretudo, quando valoriza o espaço rural e as tradições da roça transmitidas pelas gerações, além de favorecer a integração entre espaços urbano e rural.Palavras-chave: Festa Junina. Gênero. Juventude rural. ABSTRACT:We have purposefully tried to share research data, developed in an Agrarian Reform Settlement, in the country of São Paulo state. We have studied the minds and thoughts of female teenagers, concerning issues such as youth, education, future perspectives and social relationships. We have witnessed the June Party, in this settlement, rising as a strengthening element of identity and belonging, valuing the rural environment. The teenagers’ speeches show a cycle of life permeated by prohibition, and the parties within this settlement become means for the young girls to celebrate this cycle of life. The June Party in the area researched preserves and values the rural traditions transmitted through generations, besides being an opportunity of integration between urban and rural areas.Keywords: June Party; culture, youth; gender.

The effect of Ru on Ti50Pd50 high temperature shape memory alloy: a first-principles study

ABSTRACTThe stability of the Ti50Pd50-xRux alloy was investigated using first-principles density functional theory within the plane-wave pseudopotential method. Firstly, the Ti50Pd50 gave equilibrium lattice parameter and lowest heats of formation in better agreement with experimental data to within 3%. The heat of formation decreases with an increase in Ru concentration, consistent with the trend of the density of states which is lowered at the Fermi level as Ru content is increased which suggests stability. It was also found that from the calculated elastic constants the structures showed positive shear modulus above 20 at. % Ru, condition of stability. Furthermore, the addition of Ru was found to strengthen the Ti50Pd50-xRux system at higher concentrations. The thermal coefficients of linear expansion for the Ti50Pd31.25Ru18. 75 are higher at low temperature, and that the TiPd-Ru system tends to expand more at low content of 18.75 at. % Ru than at higher content. Partial substitution of Pd with Ru was found more effective as a strengthening element and may enhance the martensitic transformation temperature of the Ti50Pd50 alloy.

Influence of Ru on the Microstructure of Ni-Base Single Crystal Superalloys

Addition of Ru in Ni-base single crystal superalloys had been used to improve the elevated temperature strength and other multiple properties. Significant decreases in stacking fault energy of the γ phase and the volume fraction of γ′ phase are observed with the addition of Ru. As well as serving as an effective solid-solution strengthening element in high refractory content Ni-base single crystal superalloys, Ru additions are able to effectively strengthen both the γ and γ′ phases and suppress the formation of TCP phases. Due to the changes in the partitioning behavior of elements and the slight decrease in the supersaturation of refractory elements in γ phase associated with Ru additions, high temperature creep resistance and the microstructural stability of the alloy are improved remarkable. The influence of Ru on the microstructure of Ni-base single crystal superalloys is reviewed.

AA 2124

AA 2124 is a heat treatable aluminum plate alloy in which copper is the principal strengthening element. The alloy carries reduced allowable silicon and iron contents to ensure improved toughness. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on low and high temperature performance, and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Al-310. Producer or source: Various aluminum companies.

COPPER ALLOY No. C86100

Copper Alloy No. C86100 is a copper-zinc-aluminum-manganese-iron alloy, sometimes classified as a high-strength yellow brass. The principal strengthening element is aluminum. Its tensile strength is typically 95,000 psi (655 MPa). It has a good combination of strength and ductility along with good resistance to corrosion. Its typical uses are marine castings, gears, gun mounts, bearing and bushings. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive strength as well as fracture toughness. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Cu-510. Producer or source: Copper alloy foundries.

COPPER ALLOY No. 862

Copper Alloy No. 862 is a copper-zinc-aluminum-manganese-iron alloy; aluminum is the principal strengthening element. It is classified as a high-strength yellow brass; its typical tensile strength is 95,000 psi. It has an excellent combination of strength and ductility along with good resistance to corrosion. Its numerous applications include cams, valve stems and marine hardware. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and compressive strength as well as fracture toughness. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Cu-365. Producer or source: Copper alloy foundries.