| Popis: |
Mechanical properties of poly(p-phenylene vinylene) (PPV) were determined by quasi-static and dynamic nanoindentation. PPV films were prepared by thermolytic conversion of poly[p-phenylene (tetrahydrothiophenium)ethylene chloride] precursor films, at different temperatures. The mechanical properties of the films showed a dependence on the extent of conversion and chemical composition of the films. The storage modulus, E r ′ , and plasticity decreased with an increase in conversion, whereas the loss modulus, E r ″ , showed the opposite trend. Both the precursor and the fully-converted PPV films were found to have significantly lower E r ″ than E r ′ , consistent with the glassy nature of the polymers at room temperature. The fully-converted PPV polymer was found to have room-temperature storage and loss moduli of 4.4 and 0.2 GPa, respectively. A comparison of the contact mechanical properties of the isotropic PPV films synthesized in this work with previously reported values for stretch-oriented anisotropic films determined by conventional tensile testing methods is also discussed. |
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