Poly(1,4-cyclohexanedimethylene 2,6-naphthalate) polyester with high melting point: Effect of different synthesis methods on molecular weight and properties

In the current manuscript, a new approach for the synthesis of poly(1,4- cyclohexanedimethylene 2,6-naphthalate) (PCHDMN) derived from dimethyl 2,6-naphthalenedicarboxylate (2,6-DMN) and 1,4-Cyclohexanedimethanol (CHDM) via melt polycondensation method is introduced. The effect of three different synthesis pathways, polycondensation time and temperature on polyesters molecular weight increase has been investigated. All of the prepared samples were characterized measuring their intrinsic viscosity (IV), thermal properties and morphology with differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD), respectively. The results demonstrated the effectiveness of the synthesis pathway proposed for the preparation of PCHDMN, resulting in high molecular weight (IV value around 0.5 dL/g) and much shorter reaction time. Melt polycondensation temperatures above melting point of polyester should be avoided to be used due to the decomposition of polyester. This was proved by thermogravimetric analysis (TGA) and Pyrolysis-gas chromatography–mass spectroscopy analysis (Py-GC/MS)