Viscoelastic properties of copolycarbonates comprising isosorbide and 1,4-cyclohexanedimethanol.

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 T_g, i.e., peak temperature of α dispersion, increased with the ISB content. It was found from oscillatory shear modulus that the rubbery plateau modulus G_N⁰ decreased with the ISB content. The entanglement molecular weights M_e 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]