Morphology and physical properties of poly(butylene terephthalate)

Abstract

SynopsisLiquid nitrogen-quenched PBT samples produce much larger spherulites of an optic axis orientation different from that of the air-cooled samples. Optical and scanning electron microscopy show that glass fibers in the glass-reinforced PBT sample nucleate the growth of well-defined spherulites along the glass fiber axis. Fracture studies at temperatures below and above the T, indicate, respectively, brittle and ductile interspherulite boundary fracture. From dynamic mechanical studies, three transitions designated by a (flow transition), j3 (Tg), and y (secondary relaxation) are observed.The magnitudes of the j3 and y transitions are larger for the more amorphous quenched sample than the air-cooled sample, suggesting their amorphous phase origin. Addition of glass fibers raises the dynamic modulus and flow temperature, but suppresses the y transition without significantly affecting the melting and glass transition temperatures.

A new addition to the family of polyesters—Synthesis and characterization of novel (alternating) poly(ether ester)s, poly(butylene 3-/4-hydoxy benzoate)s

“…These diffraction pattern reportedly correspond to triclinic unit cell structure. It has also been reported that the solution cast PBT exhibits spherulitic morphology [17]. In comparison, PB-4-HB did not show strong and distinct diffraction patterns similar to that of PBT in the range 10°to 20°in accordance with its relatively weaker semi-crystalline nature.…”

“…In the WAXRD analysis UPEE 1 showed a halo pattern typical of amorphous polymers and the PB-4-HB showed WAXRD pattern typical of semi-crystalline polymers. In the WAXRD analysis, PBT has been reported to show strong diffraction peaks at 2θ016.0°, 17.3°, 20.6°, 23.4°and 25.2° [17]. These diffraction pattern reportedly correspond to triclinic unit cell structure.…”

Multiple Melting Behavior of Poly(thiodiethylene terephthalate): Further Investigations by Means of X‐ray and Thermal Techniques

“…An analogous situation has been observed for many polyesters, among which a well-known example is represented by poly(butylene terephthalate). [26] As far as the overall kinetic constant k n is concerned, two distinct trends with T c can be observed (see Figure 11), each of them being relative to one of the two crystalline phases.…”

Dielectric relaxation spectroscopy of poly(ethylene terephthalate)

“…PET, PBT and polycarbonate are polyesters of similar chemical structure in that their repeat units each contain carbonyl groups and phenyl rings in comparatively close proximity. Many workers (see, for example, refs 17, 29–33) attribute the β‐absorptions to carbonyl‐driven localized motions of carbonyl and phenyl groups. The localized nature of these motions is indicated by the observation that the shape and location of the β loss peak in PET is unaffected by crystallinity.…”