Cover: The picture on the cover shows the morphology of the skin of a 80/20 amorphous polyamide/poly(amino‐ether) blend.Further details can be found in the Full Paper by A. Granado, J. I. Eguiazábal,* and J. Nazábal on page 281.

Poly(e-caprolactone) (PCL)/poly(amino ether) (PAE) blends were obtained by injection molding without any previous extrusion step in an attempt to (i) contribute to the knowledge of the relation between structure and mechanical properties in these type of blends composed of a rubbery and a glassy polymer and (ii) to find out to which extent are the PCL/PAE blends compatible, and therefore whether the biodegradability of PCL can be added as a characteristic of PAE-based applications. PCL/ PAE blends are composed of a crystalline PCL phase, a pure amorphous PCL phase, and a PAE-rich phase where some PCL is present. The presence of some dissolved and probably unreacted PCL in the PAE-rich phase led to a low interfacial tension as observed by the small size of the dispersed particles and the large interfacial area. The dependence on composition of both the modulus of elasticity and the yield stress of the blends was parallel to that of the orientation level. The elongation at break showed values similar to those of PAE in PAE-rich blends, and was slightly synergistic in very rich PCL compositions; this behavior reflects a change in the nature of the matrix, from glassy to rubbery.

ABSTRACT:The structure, thermal and mechanical properties of blends of poly(butylene terephthalate) (PBT) and a poly(amino-ether) (PAE) barrier resin obtained by direct injection molding are reported. The slight shift of the glass transition temperatures (T g ) of the pure components when blended is attributed to partial miscibility rather than interchange reactions. Both the small strain and the break properties of the blends were close or even above those predicted by the direct rule of mixtures. The specific volume of the blends appeared to be the main reason for the modulus behavior. The linear values of the elongation at break indicated that the blends were compatible, and were attributed to a combination of good adhesion between the two phases of the blends and the small size of the dispersed phases.

Summary: The structure and properties of blends of a PCTG and a PAE resin obtained by direct injection molding have been studied. The blends were almost immiscible, and were composed of a nearly pure PAE phase and a mixed PCTG‐rich phase containing minor PAE amounts. Electron microscopy observations showed a high intermixing level between both components. The permeability data indicated an improved barrier protection of PCTG upon PAE addition. The Young's modulus and the yield stress of the blends followed a linear behavior with respect to composition, while values close or slightly below linearity were observed for the break properties. The combined effects of the small dispersed particle size and the proposed good interfacial adhesion are stated as the main factors responsible for the positive mechanical behavior. The impact strength showed an unexpected variability for PCTG‐rich blends, which is attributed to a ductile‐brittle transition of PCTG.Ductility of PCTG/PAE blends vs. composition.magnified imageDuctility of PCTG/PAE blends vs. composition.

ABSTRACT:The effects of reprocessing by extrusion for up to five cycles, at both the usual (200°C) and an extreme (230°C) temperature, on the structure and mechanical properties of a poly(amino ether) (PAE) resin were studied. A slight darkening and viscosity increase was observed, mainly upon reprocessing at 230°C. The melt flow index and solubility analysis indicated that grafting and crosslinking reactions took place, respectively, after reprocessing at 200 and 230°C. The YoungЈs modulus and the yield stress of PAE increased slightly with successive extrusion cycles. This was attributed to the viscosity-induced increase in orientation, and to a minor extent to the partially grafted/ crosslinked nature of the samples. The decrease in the ductility was more noticeable in the samples reprocessed at 230°C, and was attributed to the reduced ability to elongate of partially grafted and partially crosslinked structures present after reprocessing, respectively, at 200 and 230°C.