Polymer blends exhibit properties that are highly dependent on interactions between components, typically quantified by the Flory-Huggins interaction parameter, χ. Prediction of blend phase behavior requires characterization of the temperature dependence of χ. Polyolefins and polydienes are important materials with commercial relevance in elastomer applications. The majority of previous studies on the thermodynamics in polyolefin and polydiene systems have focused on polymer pairs within the same class (i.e. polyolefin/polyolefin and polydiene/polydiene blends), which generally exhibit a small and weakly temperature dependent χ. There is little quantitative information on thermodynamic interactions in systems that contain both polydienes and polyolefins. We have characterized interactions in polyolefin and polydiene blends, composed of 1,2-polybutadiene, 1,4-polyisoprene, poly(ethyl ethylene), and poly(ethylene-<i>co</i>-ethyl ethylene), utilizing small angle neutron scattering (SANS). SANS data were analyzed through Random Phase Approximation and Zimm analyses in order to extract χ as a function of temperature. We observed an unusually large χ parameter in these polydiene/polyolefin blends. We also studied the impact of partial saturation of the polydiene on the thermodynamics of polydiene/polyolefin blends. The applicability of the random copolymer theory to predict χ(T) behavior in these blends was evaluated.

Thermodynamic interactions in polydiene/polyolefin blends

ACS Spring Meeting 2021

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