Relationship between the end-cap structure of polycarbonates and their impact resistance

Using various phenols as the end-capping agent, polycarbonates (PCs) with the same degrees of polymerization were prepared by phosgenation of bisphenol A. The end-capping agents greatly affected the fluidity, thermal resistance and impact resistance of the PCs. It was found that, compared to commercially available PCs end-capped with 4-tert-butylphenol, the PCs end-capped with 4-tert-octylphenol or 4-α-cumylphenol were superior in impact strength with a better balance of fluidity, thermal resistance and impact resistance. From the results of dynamic mechanical measurements, improvement in performance is explained by the high mobility of my prepared PCs as compared to commercial ones, that is, energy dissipation occurs significantly in the polymer molecule, and contributes to the improvement in impact resistance.