Gert Schwarz, H. Kricheldorf
May 1, 1995
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0
Influential Citations
26
Citations
Journal
Macromolecules
Abstract
4'-Acetoxybiphenyl-4-carboxylic acid (4'-ABCA) was polycondensed under six different reaction conditions. In 1-chloronaphthalene at 235 o C, oligomers with a degree of polymerization (DP) of 3-4 were obtained. Polycondensation in bulk at 270 o C yielded fibrous oligomers with a DP>10. Polycondensation of 4'-ABCA in Marlotherm-S at 320 o C yielded a poly(4'-hydroxybiphenyl-4-carboxylic acid), poly(4'-HBCA), without marked morphology. At 400 o C and low monomer concentration, whisker-like crystals were obtained. These whiskers possess an orthorhombic crystal lattice at room temperature which undergoes a reversible change to another orthorhombic smectic-E-like crystal lattice around 245 o C. This transition includes a volume expansion. Around 410 o C a second phase transition to a smecticB-like phase occurs. At 585 o C simultaneous melting and degradation take place, which mainly involves a Fries rearrangement