Whiskers 14. Morphology and Thermal Properties of Copolyesters of 4-Hydroxybenzoic Acid, Terephthalic Acid and Hydroquinone

Abstract

In addition to the homopolyesters, poly(4-hydroxybenzoate) and poly(4-phenylene terephthalate), two series of copolyesters have been prepared with a systematic variation of the molar ratio. The first series was prepared by polycondensation of 4-acetoxybenzoic acid, terephthalic acid and acetylated hydroquinone in a liquid inert reaction medium at 400 °C. The second series was prepared under the same reaction conditions but from silylated 4-acetoxybenzoic acid and silylated terephthalic acid and showed a considerably higher 4-hydroxybenzoate/terephthalate ratio than expected from the feed ratio. The composition of these copolyesters was checked by 1H NMR spectroscopy after hydrolysis. All copolyesters proved to be highly crystalline regardless of the molar composition. WAXS measurements were conducted with synchrotron radiation up to 450 °C. These WAXS patterns indicate a gradual phase transition between 150 and 300 °C which is not detectable in the DSC curves. For the copolyesters containing > 50 mol% or 4-Hybe (4-hydrobenzoic acid) units one or two reversible first-order phase transitions were found in the DSC traces. Electron microscopy revealed that all these copolyesters are crystal powders consisting of particles of irregular shape. However, copolycondensations of silylated 4-acetoxybenzoic acid with silylated terephthalic acid and acetylated hydroquinone yielded copolyesters with a ‘potato-chip morphology’.

Morphology Control of Aromatic Polymers in Concert with Polymerization

“…Copolymerizations of ABA, terephthalic acid and 1,4-diacetoxybenzene were investigated. 51 Copolyesters had been prepared with a systematic variation of the molar ratio in a liquid inert reaction medium at 400 C. All copolyesters proved to be highly crystalline regardless of the molar composition. All these copolyesters are crystalline powders consisting of particles of irregular shape.…”

Morphosynthesis of poly[4‐(1,4‐phenylene)oxyphthalimide] and copolymers prepared by reaction‐induced crystallization during polymerization

“…The copolymerization influences significantly the morphology and the molecular orientation, and the clear morphology is generally damaged by the copolymerization because of the structural irregularity 17, 28–31. However, if the oligomers composed of particular composition is selectively precipitated due to the difference in the solubility of the oligomer, crystals having clear habits were created even in a copolymerization system by means of the crystallization of oligomers.…”

Preparation of Poly(4′-oxy-4-biphenylcarbonyl) Needlelike Crystals with the Aid of Copolymerization

“…Although some copolyester crystals have been successively prepared by constrained thin film polymerization, − it is generally difficult to control the morphology of the crystals in copolymerization systems. However, if the oligomers having particular composition can be selectively precipitated based on the difference of solubility, a clear morphology of the crystals can be created even in a copolymerization and terpolymerization system by using the crystallization of oligomers. − …”

“…However, if the oligomers having particular composition can be selectively precipitated based on the difference of solubility, a clear morphology of the crystals can be created even in a copolymerization and terpolymerization system by using the crystallization of oligomers. [18][19][20][21][22][23][24] This paper describes new findings on the fabrication of the POBP needlelike crystals with the aid of copolymerization of APBA and ABA.…”