Fundamental Study on Binary Blends of Thermotropic Semiflexible Polyester and Flexible Polyester

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SUMMARY CTS-9614929 C.D. Han University of Akron A fundamental study is being conducted on binary blends of main-chain thermotropic semiflexible polyester (MTSP) and flexible polyester. Emphasis will be placed on developing a method(s) whereby an enhancement of the mechanical properties of flexible polyesters can be realized by blending with a MTSP. It is proposed to synthesize a series of MTSP with lateral substitution, and then prepare binary blends with a commercially available flexible polyester, poly(butylene terephthalate) (PBT) or polycarbonate (PC). Using various blends of MTSP and PBT (or PC), which will be prepared during the course of the proposed study, the investigation will include: (1) thermal transitions using differential scanning calorimetry (DSC); (2) equilibrium phase behavior in the nematic region of MTSP using DSC and polarizing optical microscopy; (3) transient/steady-state shear flow and oscillatory shear flow behavior in both the isotropic and nematic regions of MTSP using a cone-and-plate rheometer; (4) the structure in the nematic and solid states, respectively, using variable-temperatures wide-angle X-ray diffractometry; and (5) the mechanical properties of fabricated specimens. The primary objective of the proposed research project is to establish phase behavior-rheology-morphology-property relationships in binary blends consisting of a flexible polyester and a main-chain thermotropic semiflexible polyester (MTSP).