Structural characterization and mechanical behavior of metallocenic copolymers of ethylene and 5,7-dimethylocta-1,6-diene |
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Authors: | María L Cerrada Rosario Benavente José M Pereña Ernesto Pérez Jorge Moniz-Santos M Rosário Ribeiro |
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Institution: | 1. Instituto de Ciencia y Tecnología de Polímeros (CSIC), C/ Juan de la Cierva 3, 28006 Madrid, Spain;2. Grupo de Estudos de Catálise Heterogénea, Instituto Superior Técnico, Av. Rovisco País, 1049-001 Lisboa, Portugal |
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Abstract: | The relationships between structure and mechanical properties have been established in several copolymers of ethylene and 5,7-dimethylocta-1,6-diene synthesized by a metallocene catalyst. A dependence with composition and polymerization temperature has been found for different structural and mechanical parameters. The branches cannot be incorporated into the orthorhombic crystal lattice and, consequently, structural parameters such as crystallinity and crystal size are considerably affected as 5,7-dimethylocta-1,6-diene content increases in the copolymer. These structural changes influence significantly the rigidity of the copolymers and a decrease of this parameter, determined from either storage modulus or microhardness, with increasing 5,7-dimethylocta-1,6-diene molar fraction is found. The location of the different viscoelastic relaxations is also strongly dependent on composition. |
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Keywords: | crystallinity ethylene-5 7-dimethylocta-1 6-diene copolymers metallocene catalysts microhardness relaxation |
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