The Density Fluctuations of Polycarbonate under Deformation by Time-resolved small angle X-ray Scattering

Polycarbonate(PC) in an excellent thermoplastic with high impact strength, good transparency and so on. However, PC becomes brittle by annealing below the glass transition temperature. The mechanism of this phenomenon, which is so-called physical aging, is not clarified. To understand this phenomenon, we focus on density fluctuations of PC. By using a strong X-ray source of synchrotron, this density fluctuations can be detected under deformation. In this study, the change with density fluctuations of PC under deformation is investigated by using time-resolved small angle X-ray scattering. PC sample used in this study is a commercial polymer (viscosity average molecular weight Mv=19,500). Time-resolved small angle X-ray scattering is carried out under a constant load at BL05XU, SPring-8, Japan. At steady state, the isotropic scattering pattern is detected. After applying a load, the scattering pattern become anisotropic and the scattering intensity is enhanced in the parallel direction of load. This means the density fluctuations are enhanced by deformation. After necking, the density fluctuations are enhanced at an accelerating rate. We will discuss the detailed change of density fluctuations in this presentation.