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6201 aluminum alloy is mostly used in electrical conductors for overhead transmission lines due to its excellent mechanical and electrical properties besides to an excellent corrosion resistance. This alloy is heat treatable and the thermal treatment is performed with the objective of obtain the optimal properties for its application. In this work it was studied the effect of different deformation grades, time variation of natural aging as well as the time and temperature of artificial aging on the evolution of mechanical and electrical properties. It was found that solution treated wires at 560°C by 4h, 14 days natural aged, 92% cold deformed and artificial aged at 165°C by 7h, reach a tensile stress of 326 MPa and an electrical conductivity of 57.2%IACS (International Annealed Copper Standard).

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The boundary conditions of rubber compounds on solid surfaces during extrusion has long been a subject of question. The concerns of Mooney on this topic date back 60 years. He continued to return to this question throughout his career. In more recent years Vinogradov and his coworkers have called attention to slip phenomena occurring in the extrusion of elastomers through dies. This is associated with fluctuating pressure losses which occur at the onset of extrudate distortion. Such behavior has also been observed with rubber-carbon-black compounds. More recently, Turner and Moore have developed a pressurized rotational rheometer to characterize this type of behavior in rubber compounds. We have recognized the importance of this problem in our own laboratories. Marker experiments have been used in extrusion of rubber compounds to detect slippage. In the present paper, we describe an experimental study of the response of gum elastomers and their carbon black compounds in a pressurized Mooney viscometer of the general design of Turner. We look first specifically at the variations of steady torque (shear stress) with the magnitude of applied pressure. We then look at the characteristics of sheared samples and the responses to pressure transients.

A comparative experimental study of the rheological properties of four cis-1,4 polyisoprenes, two naturally occurring and two synthetic, is reported. The two naturally occurring elastomers are from the hevea tree and guayule bush, and the synthetics are produced by alkyl lithium and Ziegler catalysts. Transient and steady state shear viscosity, stress relaxation and elongational stretching experiments were carried out at 100°C. Shear viscosity was measured using creep and constant shear rate modes in a sandwich viscometer as well as with a capillary rheometer. The hevea based elastomer has the highest viscosity and maximum relaxation time. The likeliest reasons for the higher viscosity and memory of the hevea is the presence of large amounts of gel and higher levels of long chain branching than in the other cis-1,4 polyisoprenes. Rheological measurements are also reported for compounds with 0.1 and 0.2 volume loadings of carbon black. Yield values are observed for the 0.2 loading compounds.