Person:
Seoane Rodríguez, Benjamín

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First Name
Benjamín
Last Name
Seoane Rodríguez
URI
https://hdl.handle.net/20.500.14352/84030
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Area
Física Aplicada
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End date: 1999 × Start date: 1998 ×

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    Diffusional characteristics of coextruded linear low-density polyethylenes prepared from different conditions of processing
    (Journal of applied polymer science, 1998) García Villaluenga, Juan Pedro; Seoane Rodríguez, Benjamín; Compañ, V.
    The permeability and diffusivity of oxygen, carbon dioxide, nitrogen, and helium have been obtained for a range of linear low density polyethylene (LLDPE) films prepared from the same raw materials but with different processing conditions. The measurements were carried out by means of a permeation technique over the temperature interval where the alpha-relaxation processes were observed in earlier studies. The temperature dependence of the permeability and diffusion coefficients of gases shows 2 well-differentiated regions in all films. The break temperature of these regions is approximately located at the same temperature as the alpha-relaxation takes place. Both the permeability and their temperature dependence do not show a noticeable influence on the processing conditions. The effect of processing conditions on the diffusivity seems to be more complex. Differences are observed for different films in the diffusion coefficients, in the case of oxygen, and in their change with the temperature, which is particularly marked in the case of carbon dioxide. Fujita's free volume model has been applied to diffusivity data in order to study the influence of films microstructure in gas permeation properties through them.
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    Influence of drawing on gas transport mechanism in LLDPE films
    (Polymer, 1998) García Villaluenga, Juan Pedro; Seoane Rodríguez, Benjamín
    Micrographs obtained using scanning electron microscopy reveal that the drawing of co-extruded linear low-density polyethylene (LLDPE) films produces numerous changes in their surface. It is necessary to analyse the effect of these changes on gas transport in LLDPE films in order to test their efficiency in the packaging industry. Permeability of He, O-2, N-2 and CO2 has been measured in a temperature range from 25 to 85 degrees C using the variable-pressure technique with the time-lag method. Results show that the drawing process does not have a significant effect on the gas transport mechanism. The influence of drawing on the permeability of LLDPE films to gases is discussed in the light of previous studies of diffusion and mechanical relaxation in the same material and compared with results obtained in the present work.