| Abstrakt: |
Physical properties relating to chain stiffness are determined for a series of copolycarbonates of Bisphenol A and 1,1-spiro[bis(3,3-dimethyl-6-hydroxyindan)] (SBI) of varying composition. The entanglement molecular weight, Me, is derived from the rubbery plateau modulus. The recoverable compliance, %@scp@%%@ital@%J%@rsf@%%@sx@%e%@be@%0%@sxx@%,%@mx@% is determined from the dynamic moduli as well as from steady shear creep and recovery experiments. It is found that all properties change in a nonlinear fashion with SBI content. For small SBI content the entanglement density is hardly affected, whereas Tg and %@scp@%%@ital@%J%@rsf@%%@sx@%e%@be@%0%@sxx@%%@mx@% increase strongly. With further increase in SBI content the effect on Tg is less pronounced. Me, however, starts increasing progressively to about 10 times that of pure Bisphenol A polycarbonate. The functional dependence of Me on composition is not predicted correctly from group contributions. |
