Morphology and properties of novel blends prepared from simultaneous in situ polymerization and compatibilization of macrocyclic carbonates and maleated poly(propylene)

Nanoscale polymer blend morphologies, with a dispersed minor phase as small as 50 nm, have been prepared via the in situ polymerization of macrocyclic carbonates in the presence of a maleic anhydride poly(propylene) (mPP). This simple, versatile, low cost strategy successfully produced a well-defined, stable two phase nanoscale morphology with a considerable improvement in the ultimate mechanical properties and strong resistance to hydrocarbon solvents such as methylene chloride. The effect of blend composition on the rate of polymerization of the macrocyclic carbonates was studied by considering the increase i n torque during the mixing process in the batch mixer. The polymerization rate decreased considerably with increasing concentration of mPP in the blend due to the formation of graft copolymer of polycar-bonate-g-poly(propylene) (PC-g-PP). The viscoelastic behavior of the pure polymer components was found to play no role in controlling the blend morphology and size of the dispersed nanoscale particles. The blend morphology could be controlled by the compatibilization of the blend components, possibly via in situ formation of a graft copolymer. In addition, the blend morphology was strongly influenced by the value of the rotation speed (rpm) or shear rate encountered during the processing of the blends, i.e., the larger the rpm value, the finer the observed blend morphology. Both DSC and DMA data showed evidence of partial miscibility of the polymer blend components. In addition, the DMA data confirmed a preferential dissolution of mPP in polycarbonate (PC) instead of dissolution of PC in mPP as evidenced by the shift of the a-relaxation process of the PC-rich phase to lower temperatures while the a-relaxation process of the mPP was relatively unaffected regardless of the PC composition. The percentage of mPPdissolved in PC was evaluated from the reduction in the T_g value (obtained from DSC data) of PC in the blend using the Fox equation and was found to be consistent with the DMA data and preferential dissolution of mPP in PC.