Mechanical Properties and Structure of Poly(p-phenylenevinylene) Films Prepared by the Zone-Reaction Method

Abstract

The “zone-reaction method”, consisting of zone drawing (ZD) and zone reaction (ZR), was applied to chemically synthesized poly(p-phenylenevinylene) (PPV) precursor films under various applied tensions (σ) and heater temperatures (Th). The changes in the structure, tensile, and viscoelastic properties of the resulting films were investigated. It was found that orientation function (f) of the ZD films increased with draw ratio (DR), regardless of the Th and σ values, and attained 0.862 (DR = 9). ZR was subsequently performed on the ZD film. The molecular orientation and PPV content were strongly affected by the Th: The film obtained at Th = 240 °C exhibited the highest f value, as high as 0.894, while a further increase in the Th resulted in a disorientation of molecular chains. On the other hand, the absorption ratio between 632 cm-1 (C−S stretch) and 965 cm-1 (trans-vinylene C−H out-of-plane bend) (A632/A965) became almost zero at Th above 240 °C. The Young's modulus and tensile strength for the resulting ZR film respectively increased to 69.4 and 1.3 GPa from 2.1 and 0.04 GPa of as-cast original film. The dynamic storage modulus for the ZR film was the value as high as 74.7 GPa and held 40 GPa even at 350 °C, which were considerably higher than those of the typical engineering plastics.