Small Angle Neutron Scattering Studies on Miscibility of Polystyrene and Tetramethyl-Bisphenol A-Polycarbonate Blends

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Abstract
The miscible blend of polystyrene (PSH) and tetramethyl-bisphenol A-polycarbonate (TMPC) has been previously studied by differential scanning calorimetry (DSC), viscoelasticity, and microscopy. In this study, small-angle neutron scattering (SANS) has been applied to obtain the quantitative interaction parameter (X) of this blend at room temperature. Deuterated polystyrene (PSD) was used for the scattering contrast in the study. The PSD/TMPC blends show a single Tgover the whole range of composition from the DSC measurements, whicg is the same as the Tgof PSH/TMPC blend.The interaction parameter was calculated from the de Gennes scattering intensity function of miscible polymer blends, which is based on the random phase approximation. As expected for a miscible system, all X values are negative over the range of composition. It is also found that the X is composition-dependent. Furthermore, the correlation length of the concentration fluctuation is approximately twice the segment length 21–32 Å of the component polymer (PSD = 6.7 Å and TMPC = 18.3 Å), implying that the mixing of this blend is effectively at segmental level.