Browsing by Author "Hormazábal, A"

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    Dynamic mechanical and dielectric absorptions in poly(2-tert-butylcyclohexyl methacrylate) and poly(4-tert-butylcyclohexyl methacrylate)
    (2000) Calleja, RD; Bernabé, AG; Sanchez-Martínez, E; Hormazábal, A; Gargallo, L; Radic, D
    Dynamic mechanical and dielectric relaxations of poly(2-tert-butylcyclohexyl methacrylate) (P2tBCHM) and poly(4-tert-butylcyclohexyl methacrylate) (P4tBCHM) have been measured. The tert-butyl group inhibits the chair-to-chair motions in the cyclohexyl ring. However, small motions of the cyclohexyl group are still possible giving rise to subglass relaxations in both polymers. The dielectric response is more sensitive than the mechanical one to the corresponding applied force fields (C) 2000 Elsevier Science Ltd. All rights reserved.
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    Dynamic mechanical and dielectric relaxation behaviour of poly(methacrylate)s containing saturated rings with seven and eight members in the side-chains
    (2002) Díaz-Calleja, R; García-Bernabé, A; Sánchez-Martínez, E; Hormazábal, A; Gargallo, L; Radic, D
    Dynamic mechanical and dielectric behaviour of poly(cycloheptyl methacrylate), poly(cycloheptylmethyl methacrylate) and poly(cyclooctyl methacrylate) have been investigated. The study was performed by determining the components of the complex relaxation modulus E* and the complex dielectric permittivity epsilon*. Results are discussed in terms of the effect of the size and structure of the side ring. The saturated ring group shows mechanical and dielectric activity at low temperature that is analyzed in terms of the Fuoss-Kirkwood equation. The free volume for the three polymers was determined. The conductive and interfacial phenomena were studied by MacDonald and Coelho models, where the dipolar contribution was introduced. (C) 2002 Society of Chemical Industry.