Fully miscible poly(ether imide) (PEI)/poly(trimethylene terephthalate) (PTT) blends were obtained by melt mixing in an extruder followed by injection moulding. The viscosity of PEI, represented by the pressure at the extruder output, almost halved upon the addition of only 10% PTT, allowing the use of PEI in applications where either complex parts or thin sections must be moulded. The modulus of elasticity showed a synergistic behaviour which was absolute (modulus higher than that of any of the two components) in the blend with 10% PTT. This was attributed mainly to the decrease in specific volume upon blending. The additional absolute synergism in the yield stress of PEI‐rich blends and their ductile nature depict a set of properties that make these new materials attractive in a number of new applications. Copyright ­© 2003 John Wiley & Sons, Ltd.

ABSTRACT:The effects of reprocessing by extrusion for up to four cycles on the structure and mechanical properties of poly(trimethylene terephthalate) (PTT) were studied. Reprocessing did not change the chemical structure of the polymer but led to both yellowing and molecular weight reduction. Young's modulus and the yield stress of PTT remained constant or decreased with successive extrusion cycles, probably because of the observed slight specific volume increase. The continuous reduction in the break properties due to reprocessing was smaller than that found in similar polyesters and was attributed to the molecular weight reduction.

Poly(ether imide) (PEI)/bisphenol A polycarbonate (PC) blends were obtained throughout the composition range both by direct injection moulding (DI blends) and by extrusion followed by injection moulding (PM blends). Although some reaction was observed by FT IR, the blends were fully phase separated at the detection level of DMTA. An anomalous decrease in the high temperature T g of the 90/10 and 80/20 blends, was only seen in PM blends. This was attributed to an anomalous thermodynamic behaviour, after rejecting degradation, reactions or particle size as possible explanations. With the exception of the PC-rich DI blends, the morphology was fine and homogeneous. Both the modulus of elasticity and the yield stress were very close to those expected from the rule of mixtures, whatever the morphology. Unexpectedly, ductility followed the same trend, even in the less homogeneous PC-rich DI blends. This points to the very slight reactions observed, and to parameters related to chemical features of the components (such as the highly aromatic character of the components of the blend) as the main reasons for the observed ductility behaviour. [DOI 10.1295/polymj.36.705] KEY WORDS Poly(ether imide) / Polycarbonate / Blends / Mechanical Properties / Phase Structure / Blending thermoplastic polymers 1,2 to obtain multicomponent materials is one of the most useful ways to develop new polymeric materials. This is because the costs associated with the development of a new polymer do not usually compensate the likely profit. Moreover, the preparation and development of blends based on commercial polymers requires less time for the optimisation of the final product. Usually, the components of a blend are selected looking at complementary characteristics in processability, final properties or price. Thus, polymer blending can allow the combination, for example, of an expensive high performance polymer with a cheaper one, to obtain the expected performance at an advantageous cost.Poly(ether imide) (PEI) is a high performance amorphous thermoplastic with good thermal stability (T g ¼ 220 C) and remarkable modulus of elasticity and tensile strength. 3 It is used, among other applications, for advanced parts in electrical and electronics industry, in aircraft applications and in the automotive industry. Blends of PEI with poly(ether ether ketone) (PEEK), 4-6 aliphatic-aromatic polyesters, 7-20 polyarylate (PAr), 21,22 polyamide 6,6, 23,24 poly(phenylene sulphide) (PPS) and polysulfone of bisphenol A (PSU), 25 among others, have been studied and several patents 26 with polymers such as polycarbonate, polyamides, polypropylene, polysulfones and liquid crystal polymers, have been granted.Bisphenol A polycarbonate (PC) is an engineering thermoplastic with applications in a wide variety of fields, such as electronics, illuminating engineering, household, automotive industry, sports, security elements, etc. Its blends with many other polymers have been studied 27,28 or registered, 26 and some of them such as those with poly(ethylene terepht...

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