The effect of high-pressure processing on mechanical and thermal properties of four complex packaging materials (polyethylene/ethylene vinyl alcohol/ polyethylene: PE/EVOH/PE; metallized polyester/polyethylene: PETmet/PE; polyester/ polyethylene: PET/PE; polypropylene SiOx recovered: PPSiOx) was studied. Pouches of the different materials containing distilled water or olive oil as food simulants, as well as empty ones, were subjected to 400 MPa for 30 min, at temperatures of 20 or 60°C. Delamination and wrinkling were a general consequence of the high-pressure processing of multilayer polymeric systems. However, no signifi cant changes were observed regarding the mechanical properties of PE containing laminates after pressurization. PPSiOx underwent signifi cant modifi cations as SiOx completely broke down. Neither thermal property was affected by pressure, as it was the processing temperature that induced tempering effects on the crystallization behaviour of polymeric components. Only PE/EVOH/ PE, when in contact with water as a simulant, presented a decrease in the melting point temperature.

Morphological characteristics analysis before and after tensile tests were studied using scanning electron microscopy (SEM) technique to follow the failure evolution on carbon fiber reinforced polymer (CFRP) and epoxy resins. Micrograph analysis of CFRP plate before tensile test shows some intrinsic manufacturing defects, which can influence the mechanical properties of the material. Micrograph analysis after tensile test shows that cracks propagation start in manufacturing defects, which lead the carbon fiber to be pulled out instead of breaking. Thus, cracks propagate through interfacial zones affecting the sharing force between matrix and carbon fiber. For the epoxies materials, the microscopy analysis showed that although epoxies adhesive have different phase distribution before tensile test, failure surfaces are described by fine granular particles covalent bonded with matrix, and the material fails in a brittle manner when the strength outstripped these bonds. Failure process for each material correlating the mechanical properties with the morphological characteristics of materials was discussed.

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