Effect of fullerene C60 on the structure and mechanical characteristics of polyethylene: Technological aspect

Abstract

On the basis of the literature data, a retrospective analysis of the thermodynamic characteristics of dissolution of fullerene C60 in a series of single-ring aromatic solvents is presented. The effect of the molecular structure of a solvent on its dissolving capacity with respect to fullerene is studied. The parameter of the boiling temperature of the solvent normalized to its molecular mass is introduced. The correlation of this parameter with the dissolving capacity of the solvent is discussed. Special emphasis is placed on the effect of halogen-containing solvents on the dissolution of fullerene and indirectly on the development of the mechanical characteristics of films prepared from common solutions of fullerene and low-density polyethylene. For comparison, the films prepared from PE melts modified with low concentrations of fullerene are considered. The film structure is studied via X-ray analysis, optical microscopy, AFM, small-angle scattering of linearly polarized light, and DSC. The films with the maximum strength are prepared from solutions in halogen-containing solvents at a concentration of fullerene below 1 wt %. In this case, spherulites are 5–10 times smaller than those in the films cast from solutions in other solvents. In the films cast from common solutions of PE and fullerene in bromobenzene, crystal solvates C60 · 2C6H5Br are formed. It seems that the formation of the crystal solvates binds the residual solvent and thus affects the mechanical behavior of the films, thereby eliminating the plasticizing effect of residual bromobenzene. Localization of fullerene in various regions of the supramolecular structure of the films is discussed, and the morphology of the separating regions of the crystal solvate fullerene phase is analyzed.