PET-BB copolymers

While no direct evidence of liquid crystallinity in PET-BB copolymers has been reported, the high-BB-content copolymers have been shown to possess morphologies similar to those of liquid crystalline polyesters [40], and show major changes in both melt relaxation times and fiber tensile moduli, suggestive of structural organization in a frustrated liquid crystalline polymer (LCP) (Table 6.3 and Figure 6.4) [41, 42],... 

Figure 6.4 Properties of PET-BB copolymers as a function of BB content (a) tensile properties (b) viscosity, r o ( ) and relaxation time (O) [42]. Reprinted with permission from Ma, H., Hibbs, H., Collard, D. M., Kumar, S. and Schi-raldi, D. A., Macromolecules, 35, 5123-5130 (2002). Copyright (2002) American Chemical Society...

The isomeric bibenzoic acids (BBs), would appear to share similar structural features with naphthalene dicarboxylic acid. Like the PET-naphthalate copolymers, PET-bibenzoates have been demonstrated to possess moduli and glass transitions temperatures which increase with increasing levels of rigid comonomer [37-39], Unlike the PET/PEN copolymers, when the symmetrical 4,4 - I f I f monomer is substituted into a PET backbone, virtually every composition of PET-BB is semicrystalline the 2,4- and 3,4- isomers of BB, when... 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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