Synthesis of PET-based Liquid Crystalline Copolyesters: Influence of the Overall Degree of Aromaticity on Phase Segregation
Titel:
Synthesis of PET-based Liquid Crystalline Copolyesters: Influence of the Overall Degree of Aromaticity on Phase Segregation
Auteur:
Minkova, Liliya I. Milie, Rossana Filippi, Sara Polacco, Giovanni
Verschenen in:
International journal of polymeric materials
Paginering:
Jaargang 50 (2001) nr. 3-4 pagina's 373-386
Jaar:
2001-10-01
Inhoud:
Novel PET-based copolyesters have been synthesised by transesterification of PET with equimolar amounts of sebacic acid (S) and 4,4'-diacetoxybiphenyl (B) and with varying amounts of 4-acetoxybenzoic acid (H). The structure, the morphology, and the thermal properties of the PET-S-B-H copolyesters have been studied by scanning electron microscopy (SEM), polarized optical microscopy (POM), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXS). It has been demonstrated that segregation of a liquid-crystalline phase, during polycondensation, provides the driving force for compositional differentiation, with the result that the final products are “synthetic polymer blends”. The characteristics of PET-S-B-H copolymers have been compared with those of PET-S-Q-H copolyesters having the same molar composition (Q-hydroquinone). It has been shown that the phase segregation is more prominent in PET-S-B-H copolyesters than in PET-S-Q-H polymers of similar molar composition. The influence of the overall degree of aromaticity of the copolyester on the segregation phenomenon has been discussed.