Dynamic viscoelastic behavior of polybutadiene networks

Autor:	Gerard Kraus, K. W. Rollmann
Rok vydání:	2007
Předmět:	chemistry.chemical_classification Materials science General Engineering Vulcanization Polymer Carbon black Branching (polymer chemistry) Viscoelasticity law.invention Polybutadiene chemistry law Molar mass distribution Composite material Leveling effect
Zdroj:	Journal of Polymer Science: Polymer Symposia. 48:87-106
ISSN:	1936-0959 0360-8905
DOI:	10.1002/polc.5070480109
Popis:	Dynamic viscoelastic properties of polybutadiene networks, prepared by conventional sulfur vulcanization of polymers differing in primary molecular weight, molecular weight distribution, long-chain branch content, and branching pattern, were measured in the region of the viscoelastic spectrum of principal interest in dynamic applications of rubbers. At lower frequencies, the storage compliance was found to correlate closely with the fraction of free (terminal) chains in the network, while the loss compliance could be correlated with either the free end fraction or with the fraction of chain entanglements not trapped into the network by primary valence crosslinks. At higher frequencies, approaching the plateau region of the viscoelastic spectrum, effects of network structural features diminished as contributions of untrapped entanglements became more pronounced. Networks prepared in presence of a diluent exhibited the same trends as pure gum vulcanizates. Carbon black produced a leveling effect, ascribed to a second entanglement entrapment mechanism by adsorption sites on the filler surface.
Databáze:	OpenAIRE
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