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Compatible poly(trimethylene terephthalate) (PTT)/poly(hydroxy ether of bisphenol A) (Phenoxy) blends were obtained by direct injection molding throughout the composition range. Two amorphous phases with minor amounts of the other component were found in the blends. Reactions occurred in PTT-rich blends. By comparing the miscibility level of these blends with that of other blends based on polyalkylene terephthalates, it is proposed that a miscibility limit delimited by a 3/1 methylenecarbonyl ratio in the polyalkylene terephthalate exits in these blends. The synergism in the Young's modulus of the blends is discussed as a consequence of the changes in the crystallinity of PTT, the specific volume and the orientation produced by blending. Ductility is approximately proportional to blend composition, indicating compatibility, and is attributed to the combined effects of a small particle size and a good adhesion level, the latter being a consequence of the partially miscible nature of the blends.

New clay‐reinforced polymer nanocomposites based on poly(carbonate of bisphenol A) (PC)/poly(caprolactone) (PCL) blends have been obtained by mixing PC with minor amounts of PCL in which a widely dispersed organically modified montmorillonite (OMMT) was present. Upon the addition of PCL/OMMT, the Tg of the matrix and the viscosity of the nanocomposites decreased and therefore processability increased. This was attributed to both the presence of PCL and the migration of some surfactant to the polymeric matrix. The intercalation level observed by X‐Ray diffraction was similar to that obtained in PC nanocomposites, and the dispersion level was at least similar, as observed directly by transmission electron microscopy and indirectly by modulus measurements. However, the benefits of both clay and PCL were present together in the nanocomposites, besides the improved processability and the expected improvement of barrier properties. This led to increases in modulus of elasticity, yield strength, and although slight, mostly in ductility. POLYM. ENG. SCI., 46:864–873, 2006. © 2006 Society of Plastics Engineers

Exfoliated polyamide‐6 (PA6)/organically modified montmorillonite clay (OMMT) nanocomposites (PNs) were modified with partially maleinized styrene–ethylene/butadiene–styrene triblock copolymers (SEBS) at three maleinization levels in an attempt to link in these materials high toughness with appropriate small‐strain and fracture tensile properties. OMMT stayed only in the PA6 matrix, and no preferential location in the matrix/rubber interphase was observed. The increased dispersed phase size upon the addition of OMMT was attributed to interactions between maleic anhydride (MA) functionalized SEBS and the surfactant of OMMT. The rubber particle size generally decreased when the MA content of SEBS increased, and this indicated compatibilization. The subsequent good adhesion led to tough nanocomposites across a wide range of both strain rates and fracture modes. As the critical interparticle distance (τc) decreased with the MA content, and the other parameters that could influence the surface‐to‐surface mean interparticle distance did not change, it is proposed that in these PNs higher adhesion leads to a smaller τc value. Finally, the presence in the matrix of a nanostructured clay makes the rubber content necessary for the toughness jump to increase and τc to decrease. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3611–3620, 2005

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The effect of the organoclay content on the toughness of a rubbery modified amorphous polyamide (aPA)/organoclay-based nanocomposite was studied by changing the modifier (maleic anhydride) content. The dispersed rubber particle size decreased markedly with the addition of the modifier, indicating compatibilization of the nanocomposite. However, the particle size of the dispersed phase increased slightly with the organoclay content due to the interactions between the dissolved surfactant and the compatibilizer. Furthermore, we observed that the organoclay resided in the aPA matrix, and that its dispersion remained constant upon rubber addition. This resulted in materials with high stiffness and extremely large toughness values, as measured by both the standard impact strength and the essential work of the fracture method. Because the rubber content was kept constant, the inorganic part of the clay was proposed to be the main parameter that controls toughness.

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