Reactive blends of polyamide 6 with polyester elastomer using coupling agents

In situ compatibilized melt blends of polyamide 6 (PA-6) with polyester elastomer (PEL) were prepared in a corotating twin-screw extruder using two types of coupling agent (CA): diglycidyl ether of bisphenol A (DGEBA) and 1,4-phenylene bis(2-oxazoline) (PBO). The notched impact strength of PA-6 and PA-6/PEL blends increased with the addition of coupling agent, especially DGEBA, and the maximum impact toughening of the blend was obtained with 0.6 mol % DGEBA, the composition of minimum domain size observed from SEM. Viscosities of the untreated blends increased over those of the base resins at low frequencies. Viscosities of both the base resins and the blends increased with the addition of CA, and the effect was much more pronounced with DGEBA, especially for PA-6 and PA-6–rich blends. The crystallization temperature (Tc) of PEL increased over 10°C, whereas the Tc of PA-6 decreased by 2–3°C in the blends. With the addition of coupling agents, the crystallization melting temperature (Tm) and Tc of PA-6 decreased by up to 5°C with DGEBA, implying that the crystallization of PA-6 is disturbed by the in situ formed PA-6–CA–PEL or PA-6–CA–PA-6 type copolymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3966–3973, 2004