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Viscoelastic properties of copolycarbonate materials comprising isosorbide (ISB) and cyclohexanedimethanol (CHDM) were studied as a function of the ISB content. In the glassy state, β dispersion was clearly detected in the dynamic mechanical spectra. The tensile storage modulus E′ at room temperature increased with the ISB content, and the glass transition temperature Tg, i.e., peak temperature of α dispersion, increased with the ISB content. It was found from oscillatory shear modulus that the rubbery plateau modulus GN0 decreased with the ISB content. The entanglement molecular weights Me were found to be 2330–3640, which were slightly higher than that of bisphenol-A polycarbonate and much lower than those of poly(methyl methacrylate) and polystyrene. The onset shear stress of shark-skin failure at capillary extrusion was evaluated and found to increase with the ISB content. [ABSTRACT FROM AUTHOR]

Poly(ethylene- co-vinyl acetate) with 42 wt% of vinyl acetate shows autonomic self-healing at room temperature without macroscopic flow. Intermolecular diffusion of amorphous chains through the jointed boundary, which occurs because of the large amount of amorphous chains with low glass transition temperature, is responsible for the healing phenomenon. Furthermore, the healing efficiency is found to be enhanced when the separated pieces are recombined immediately after cutting. This result indicates that the cut surface has marked molecular mobility owing to the destruction of crystallites during the cutting process, which is supported by differential scanning calorimetry (DSC) measurements. The marked molecular mobility at the surface is, however, observed only for a short period after cutting, because further crystallization after cutting restricts the molecular motion. [ABSTRACT FROM AUTHOR]