Crystallization from the melt at high supercooling in finely dispersed polymer blends: DSC and rheological analysis

Abstract

Crystallization at high supercooling of polybutylene terephthalate (PBT) droplets dispersed in a molten polyethylene (PE) matrix was investigated through rheological and DSC experiments. The Palierne's emulsion model was used as a theoretical framework for studying the viscoelastic behavior of the blends in different ranges of temperature: on the one hand, when the two polymers are molten (T > 225°C) and on the other hand, when PBT droplets are at high supercooling in the molten PE matrix (130°C < T < 205°C). From rheological experimental evidences it was shown that molten and solidified droplets coexist at high supercooling. The Palierne's model was then successfully adapted to take into account the three phases (molten PE, molten PBT droplets, and solidified PBT droplets). The evolution of the behavior with the temperature is consistent with the growing amount of crystallized droplets. Moreover, a calculation taking into account the droplets size distribution and the number of nuclei is introduced to explain the crystallization behavior of three different blend ratios.© 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2573–2585, 1998

Effect of structural features of poly(butylene terephthalate) tubes on the useful properties of the loose tube/optical fibers system in the tubular optical fiber cables

“…The relative crystalline phase content in tubes, α (%), was found from the formula: where Δ H PBT = 144.5 J/g,41 and is the heat of fusion of the 100% PBT crystalline phase.…”

All-Optical Decoder for Rapid and Noncontact Readout of Thermal Barcodes

“…No freezing peak is observed for icosane (melting temperature 36.1 °C), which is likely because of a small thermal driven force (temperature difference from the room temperature is low), producing heat flux below the detection limit of DSC. The different behaviors regarding supercooling in thermal imager and DSC are probably caused by lack of nucleation site in smooth aluminum pans. − …”

Dispersed phase morphology and fractionated crystallization of high-density polyethylene in PET/HDPE blends

“…The phenomenon was also observed for polyamide 6 (PA6) in polyolefins [9]. Description of the fractionated crystallization was also given for other polymer systems such as poly(ethylene terephthalate) blended with polycarbonate (PC) [10], with high density polyethylene (HDPE) and various polyolefins in PS matrix [11][12][13] and poly(butylene terephthalate) (PBT) in polyethylene [14]. Experiments with PE or PP droplets obtained from multilayer instabilities show similar phenomena [15][16][17].…”