Cascade model for physically cross-linked elastomer: Morphological characteristics of nonionic elastomers and microcrystalline ionene elastomer

摘要

The cascade model for randomly branched f-functional polycondensates incorporated in Debye-Bueche random-two-phase model and the interference term by the interdomain interaction was found to good fit the small-angle X-ray scattering profiles of physically cross-linked amphiphilic elastomers. The samples were poly(oxyethylene)-grafted butyl rubber, butyl rubber with D-maltose derivative as pendant groups, and microcrystalline ionene elastomer composed of poly(oxytetramethylene) and 4,4'-bipyridinium unit. The hydrophilic segments of these amphiphilic elastomers aggregated in the flexible polymer matrix to form the domains that function as cross-linking sites and fillers. Good fitting for all samples by using the proposed model gave the size of the physically. aggregated domains, the average distance between the centers of neighboring aggregated domains and the their interdomain interaction distance. All samples were found to be in the vicinity of the gel point from the viewpoint of the cascade model. The results imply that the cascade theory for gelation is useful for the morphological analysis of physical networks like a thermoplastic elastomer. The relationship between the morphology and the properties was discussed combining with the results of transmission electron microscopy, differential scanning calorimetry, dynamic mechanical analysis, and tensile measurement. [References: 28]