Spatially heterogeneous dynamics in thermoset resins below the glass-transition temperature: Effect of temperature and composition

TitleSpatially heterogeneous dynamics in thermoset resins below the glass-transition temperature: Effect of temperature and composition
Publication TypeJournal Article
Year of Publication2000
AuthorsWang, C. Y., and M. D. Ediger
JournalJournal of Polymer Science Part B-Polymer PhysicsJournal of Polymer Science Part B-Polymer PhysicsJournal of Polymer Science Part B-Polymer Physics
Volume38
Pagination2232-2239
Date PublishedSep
Type of ArticleArticle
ISBN Number0887-6266
Accession NumberWOS:000088771300003
Keywordsbimodal distribution, COMPONENT DYNAMICS, crosslink, DEUTERON NMR, DIBLOCK COPOLYMERS, DIELECTRIC-RELAXATION, glass transition, MISCIBLE POLYMER BLEND, MULTIDIMENSIONAL NMR, nonexponential relaxation, O-TERPHENYL, photobleaching, probe reorientation, spatially heterogeneous dynamics, STRUCTURAL RELAXATION, SUPERCOOLED ORTHO-TERPHENYL, thermoset resins, translational diffusion
Abstract

A photobleaching technique was used to measure the rotational dynamics of rubrene dispersed in thermoset resins. The matrices were polymerized from mixtures of two monomers with five different compositions. At temperatures below the glass-transition temperature, probe rotational correlation times were shorter and showed a much weaker temperature dependence than those observed in glassy homopolymers. The probe correlation functions became increasingly nonexponential as the amount of the minor component in the matrix increased, presumably because a more heterogeneous set of environments resulted. Dynamics in the single-component sample were quite homogeneous at room temperature. In contrast to homopolymer systems, a bimodal distribution of local relaxation times developed with the addition of the second component. At a given polymer composition, this bimodal distribution changed shape with temperature in a reversible manner. (C) 2000 John Wiley & Sons, Inc.

Short TitleJ. Polym. Sci. Pt. B-Polym. Phys.J. Polym. Sci. Pt. B-Polym. Phys.
Alternate JournalJ. Polym. Sci. Pt. B-Polym. Phys.