Linear and non linear mechanical properties of miscible polymer blends near glass transition

Abstract : Miscible polymer blends of Polybutadiene (PB) and Styrene Butadiene Rubber (SBR) are studied in order to relate their microscopic structure to their macroscopic linear and nonlinear mechanical properties. The dynamic heterogeneities of polymer blends are particularly strong at the length scale of segmental movement associated to the alpha-relaxation (~1nm). It is neither obvious in our blend system in larger length scale involved in rubber elasticity (~10nm), nor in smaller length scale of localized motions controlling the beta-relaxation (<1nm). We assume that a blend can be considered as an ensemble of domains of various local glass transition temperatures. Using calorimetric data, with or without aging, we probe the distribution of glass transition temperature P(Tg) of miscible polymer blends. Using self-consistent averaging method inspired by the Olroyd-Palierne model, we predict quantitatively, with no adjustable parameter, the linear viscoelastic spectrum of our blends from that of pure polymers and the Tg distribution obtained by calorimetry. This quantitative prediction confirms thus the assumption that mechanically, a blend can be considered as an ensemble of domains each of which having a different glass transition temperature. The nonlinear mechanical properties are studied. As the system approaches glass transition, the entanglement slipping is greatly reduced due to appearance of glassy domains that immobilize the chains. Plasticity begins to be dominant as the system goes deeper into the glass transition zone, and the structural nonlinearity is the most strong when there is a percolation of glassy domains.
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Submitted on : Tuesday, December 17, 2013 - 4:12:29 PM
Last modification on : Thursday, July 4, 2019 - 11:00:05 AM
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  • HAL Id : pastel-00920019, version 1

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Peiluo Shi, Hélène Montes, François Lequeux, Régis Schach, Etienne Munch. Linear and non linear mechanical properties of miscible polymer blends near glass transition. Polymers. Université Pierre et Marie Curie - Paris VI, 2013. English. ⟨pastel-00920019⟩

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