Compatibility improvement of poly(lactic acid)/thermoplastic polyurethane blends with 3-aminopropyl triethoxysilane

Poly(lactic acid) (PLA)/thermoplastic polyurethane (TPU) blends were prepared via a melt-blending process with or without the addition of a 3-aminopropyl triethoxysilane (APTES) compatibilizer at different dosages. The addition of the compatibilizer showed improved compatibility between TPU and PLA; this led to an enhanced dispersion of TPU within the PLA matrix. With the addition of 1-phr APTES, the crystallization behavior did not vary much, but this exacerbated the formation of a second melting temperature for PLA at higher temperature. However, the addition of 5-phr APTES into the PLA/TPU blends depressed the crystallization temperature and resulted in a melting temperature depression phenomena with the disappearance of the second melting peak because of the lubricated effect of low-molecular-weight species of APTES. The addition of a low dosage of APTES improved the impact strength further from 29.2 +/- 1.4 to 40.7 +/- 2.7 J/m but with a limited improvement in the tensile properties; this indicated that a higher dispersion of the dispersed phase did not always improve all of the mechanical properties because of the low-molecular-weight nature of the compatibilizer used. The physical properties of the added modifier needed to be considered as well. A low dosage of APTES (1 phr) also increased the viscosity because of the improved interaction between TPU and PLA at all of the investigated shear rate regions, but a higher dosage of compatibilizer induced another plasticizing effect to reduce the viscosity. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42322.