Polybutylene terephthalate glass transition temperature

Blends of polybutylene terephthalate and polyethylene terephthalate are believed to be compatible in the amorphous phase as judged from (a) the existence of a single glass-transition temperature intermediate between those of the pure components and (b) the observation that the crystallization kinetics of the blend may be understood on the basis of this intermediate Tg. While trans esterification occurs in the melt, it is possible to make Tg and crystallization kinetics measurements under conditions where it is not significant. When the melted blend crystallizes, crystals of each of the components form, as judged from x-ray diffraction, IR absorption, and DSC. There is no evidence for cocrystallization. There is a slight mutual melting point depression. 

The binary blends of polycarbonate with polybutylene terephthalate (PBT/PC) or polyethylene terephthalate (PET/PC) are now known to be essentially phase separated blend systems exhibiting two glass transition temperatures in each case, one for the polycarbonate-rich phase, and another for the polyester-rich phase. [Murff et ah, 1984 Huang and Wang, 1986 Wahrmund et ah, 1978]. The evaluation of the amorphous phase miscibility... 

Electron radiation at a radiation dose of 365 kGy causes a shift in glass transition temperature of crosslinkable polybutylene terephthalate from 53 (without irradiation) to 70 °C. The crosslinked polybutylene terephthalate becomes stiffer and slightly brittle. Its long-term behavior is not impaired by irradiation at 365 kGy, Figure 5.146 [739]. With increasing irradiation and/or crosslinking, its melt temperature decreases. 

PEI forms miscible blends with polyesters such as polybutylene terephthalate (PBT) and polyethylene terephthalate (PET). These blends have a single glass transition temperature between that of the PEI... 

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