Premium
Phase behavior of blends of poly(ethylene terephthalate) with liquid‐crystalline polymers
Author(s) -
Magagnini Pierluigi,
Tonti Maria S.,
Masseti Marco,
Paci Massimo,
Minkova Lilia I.,
Miteva Tsenka T.
Publication year - 1998
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.10328
Subject(s) - materials science , copolyester , differential scanning calorimetry , transesterification , crystallization , ethylene , polymer , polymer chemistry , polymer blend , phase (matter) , scanning electron microscope , chemical engineering , polyester , copolymer , composite material , organic chemistry , catalysis , chemistry , physics , engineering , thermodynamics
Poly(ethylene terephthalate) (PET) was melt blended with several liquid‐crystalline polymers (LCPs), both with and without Ti(OBu) 4 catalyst. The LCPs, referred to as VA, LC5, LC3, and SBH, respectively, were Vectra‐A950, Rodrun LC‐5000, Rodrun LC‐3000, and a laboratory copolyester of sebacic acid (S), 4,4′‐diacetoxybiphenyl (B), and 4‐acetoxybenzoic acid (H). Their degree of aromaticity decreases in that order. The phase behavior and the morphology of the blends were studied by differential scanning calorimetry and scanning electron microscopy. All the LCPs retard the dynamic crystallization of PET. The lower the LCPs degree of aromaticity, the more pronounced was the effect. It was not possible to obtain any evidence of ester exchange reactions by the reactive blending of PET with VA. On the contrary, appreciable changes of phase behavior and morphology were observed under comparable conditions for the other blends. With LC5 and LC3, the transesterification process predominantly involved the ET‐rich phase of those polymers. Extensive transesterification occurred between PET and SBH, as proven by the gradual formation of a quasi homogeneous material, with lowered temperatures and enthalpies of fusion and crystallization. For blends with more than 25% SBH, homogenization is followed by the segregation of a new, highly aromatic phase.