Polyethylene 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. 

Kanemitsu and Einami (1990) investigated the role of the polymer on hole transport in a series of 2-(p-dipropylaminophenyl)-4-(p-dimethylaminophenyl)-5-(o-chlorophenyl)-l,3-oxazole (OX) doped polymers. The polymers were a polyarylate (PA), bisphenol-A polycarbonate (PC), poly(methyl methacrylate) (PMMA), poly(styrene) PS, poly(vinyl chloride) (PVC), polyethylene terephthalate) (PET), and poly(vinyl butyral) (PVB). The glass transition temperatures of the polymers range from 322 (PVB) to 448 K (PA). The temporal features of the photocurrent transients were strongly dependent on the polymer. Figure 76 shows the results. The field was 4.0 x H)5 V/cm and the temperature 295 K. The transients were near rectangular for PS, PET, PA, and PMMA, and highly dispersive for PVC land PVB. This was attributed to the fact... 

It is well known from diffusion theory that different types of polymers have different diffusion behaviours. For example, the polyester type polymers like poly(ethylene terephthalate) (PET), poly(ethylene naphthalate) (PEN) and polycarbonate (PC) as well as rigid poly(vinyl chloride) (PVC), which have a high glass transition temperature, are low diffusive polymers. The migration of potential contaminants in these polymers will result in low migration values. In contrast, polyolefins like high density polyethylene (HDPE), polypropylene (PP) or low density polyethylene (LDPE), which... 

Figure 10.7 DSC curves of polyethylene terephthalate)-poly(acrylonitrile-butaliene-styrene) (PET-ABS) blends (a) conventional DSC first and second heating curves with heating and cooling rate of lOKmin-1 and (b) temperature modulated DSC (TMDSC) first heating curves with /3=2Kmin 1, p = 60s and 5= 1K. Tg, glass transition temperature. (Reproduced with permission from T. Hatakeyama and F.X. Quinn, Thermal Analysis Fundamentals and Applications to Polymer Science, 2nd ed., John Wiley Sons Ltd, Chichester. 1999 John Wiley Sons Ltd.)...

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... 

Many crystallizable polymers can be prepared in the amorphous glassy state by rapid quenching as films. Measurements of Aglass transition temperature determined. Such results are shown for amorphous polyethylene terephthalate (PET) in Figure 13 (17). The Brillouin splittings change slope at 70°C. If both Aa>(i) and Awt can be measured, the Poisson ratio (T can be determined according to ... 

The variation of compliances with draw ratio for cold drawn polypropylene filaments examined at 20°C appeared very similar to that of high density polyethylene, with an increase in all compliances but Sii, which was insensitive to draw ratio. Ward aggregate theory was not applicable except for low draw ratios, implying that other processes intervened in addition to an orientation of pre-existing units. It was probable that even above the glass transition temperature increasing orientation led to a reduction in molecular mobility, as was known to occur in polyethylene terephthalate. ... 

Orientation of typical random coil polymer films, such as polypropylene and polyethylene terephthalate, involves stretching the film at a temperature above the glass transition temperature (Tg) and below the melt temperature (Tm) [5]. This allows the polymer chains sufficient mobility to be aligned in the strain directions, but not so much mobility that they will relax to a random state. With LCP films, the development of orientation is quite different. 

Several workers have discussed the mechanical properties of reinforced plastics [2-8]. Keating et al. [3] checked the necessity of high-temperature annealing and the degree of its impact on creep straining glass liber-reinforced polymers polyamide 6,6 and polyethylene terephthalate, which had glass transition temperatures of 58°C and 132°C, respectively. 

Abbreviations and symbols BP, biphenyl BPA, bisphenol A DF, dibenzofuran DES, diethylstilbestrol NP, nonylphenol 2-CP, 2-monochlorophenol PBS, poly (butylene succinate) PBT, poly(butylene adipate/terephthalate) PCL, poly(e-caprolactone) PHBV, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) PLA, poly (L-lactic acid) LDPE, low-density polyethylene PET, poly(ethylene terephthalate) +, strongly adsorbed (+), weakly adsorbed —, not adsorbed, figures in parentheses show glass transition temperature. 

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