UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2001 Meeting


Section: Polymer Physics


Title:
A DSC ANALYSIS OF THE PET/PEI BLENDS


Authors:
Tatiana Pop


Affiliation:
Physics Department, “Politehnica” University of Bucharest,

Splaiul Independentei 313 Bucharest Romania

e-mail: pop@physics1.physics.pub.ro



E-mail


Keywords:


Abstract:
In the recent years the study of polyester blends with other polymers has been directed towards a deeper insight in the miscibility and compatibility of such systems. If the polymer pair is miscible, the blend between an amorphous and a semicrystalline polymer is more interesting. It is the case of poly(ethylene terephthalate)-poly(ether imide) (PET/PEI) blend. As being an amorphous polymer, PEI presents low resistance to solvents and because of its high glass temperature PEI has a high stability in temperature. On the other part, PET, as a semicystalline polymer, has a high resistance to solvents, but its mechanical properties are not so good. The effects of blending on glass transition behaviour and on the melting temperature were analysed and reported in this paper. This analyse is also interesting as long as the melt behaviour of PET is not yet well understood. The main characteristic of the experimental results was that the number of the melting endotherms is raging from one to three, in function of the thermal history of the sample [1]. The solvent-cast blends are fully homogeneous and miscible in the amorphous state; each blend exhibits a single glass transition temperature (Tg) which can be well described by the Fox-Flory relationship. However a liquid-liquid phase separation is detected by optical microscopy above the main melting endotherms of the semicrystalline components, with a lower critical solution temperature of ~265°C (PET/PEI 50/50) [2], in contrast with the presence of an UCST as reported by others [3], This is a supplementary reason to prefer cold-crystallization over crystallization from the melt for PET/PEI blends. References 1. F.J. Medellin-Rodriguez, R.Lopez-Guillen, M.A.Waldo-Mendoza, J.Polym.Sci.,Part B: Polym.Phys.,37,1981-1990, (1999); 2. D.A.Ivanov, Tatiana Pop, D.Y.Yoon, A.M.Jonas, Polym. Mater. Sci. Eng. 81, 335-336. (1999); 3. Chen, H.-L.; Hsiao, M.-S. Macromolecules, 31, 6579, (1998).