Blends of nylon 6 ( Ny6 ) with ethylene-co-vinyl alcohol (EVOH) and EVOH modified with the introduction of carboxyl groups ( EVOH -COOH ) have been studied by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and dynamic-mechanical thermal analysis. The thermal and thermomechanical analyses of the blends show that the melting, crystallization, and relaxational behavior are affected by the blend composition and the presence of carboxyl groups on the EVOH chains. Nevertheless, microscopic and thermal investigations demonstrate the biphasic nature of the two-blend systems. Selective solvent extraction of the EVOH or EVOH -COOH phase in their blends and Fourier transform infrared analysis of the residual products indicates the occurrence of ionic linkages between the amino groups of the polyamide and the carboxyl groups of the modified EVOH, whereas specific interactions are evidenced for Ny6 / EVOH blends. Tests performed on extruded Ny6 / EVOH films show that the addition of EVOH effectively reduces the gas permeability of Nylon, whereas the addition of small amounts of EVOH -COOH helps to control and stabilize melt rheology.

The influence of the martensite content on the impact properties of three through hardened Mn steels was investigated. When the maximum amount of martensite is 50%, impact properties are influenced by the martensite content through its effect on microhardness, according to the typical behaviour of a porous material having a tough microstructure. For higher amounts of martensite (up to 100%) a transition towards a brittle behaviour is observed. In this case, carbon content has a prevailing effect over the martensite content in determining the brittleness of materials. Steels with a medium low carbon content must be used to obtain a hardened but still deformable microstructure by through hardening and, when allowed by the actual cooling conditions, by sinterhardening.

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Manganese is an alloying element that improves the strength of ferrite and the hardenability of steels. It could be a valid substitute for expensive and toxic elements (as Mo and Ni) in sintered steels, increasing mechanical properties. The hardenability of four low alloy Mn steels was studied to establish the influence of manganese on the heat treatments. The effect of Mn on steel hardenability is well established. The multiplying hardenability factors in the range 0.05-1% Mn are known, and so the hardenability of the alloy to be investigated can be predicted. The Grossmann approach was adopted, which uses cylinders with different diameters to induce different gradients of cooling rate in the cross section. Quenching experiments were carried out in the vacuum furnace, recording the actual cooling rate (on the external surface and in the central axis). The maximum cooling rate attainable is 10 K/s. Hardness, microhardness and microstructure profiles were determined, and correlated to cooling rate for the different alloying elements and C contents. The correlation of microstructure and microhardness to the actual cooling rate makes the results independent on the process parameters and applicable to each industrial condition, once the actual cooling rate in the parts is known.