Mixtures of nylon-6 and poly (m-xylene adipamide) (MXD6) undergo sufficient interchange reactions when melt blended at 290°C to give a homogeneous melt phase and a material with a single T~. However, the extent of reaction is sufficiently low that the product retains a high level of ability to crystallize. These phase-homogenized mixtures become supertough when blended with a maleic anhydride (MA) grafted elastomeric styrene- (ethytene/butene)-styrene (SEBS) triblock copolymer, i.e. SEBS-g-MA. Pure nylon-6, pure MXD6, or mixtures of the two prepared under low-temperature extrusion conditions (260°C) that do not lead to phase homogenization are not similarly supertoughened by blending with SEBS-g-MA. The reasons appear to relate to differences in elastomer particle morphology and inherent ductility for the various matrices. SEBS-g-MA blends with nylon-6 are not supertough because the rubber particles are too small. Addition of MXD6 causes the particles to become larger and of optimum size for toughening, but it is postulated that MXD6 is difficult to toughen because of low inherent ductility. The polyamide mixtures that were not phase homogenized are also inherently incompatible. The differences in rubber particle geometry are explained in terms of the functionality of the two polyamides towards reactions with anhydride groups.
Посилання на статтю:
Toughening of phase-homogenized mixtures of nylon-6 and poly(m-xylene adipamide) with a functionalized block copolymer / Y. Takeda*, H. Keskkula and D. R. Pault // Polymer. – 1992. – Vol 33. – P. 3394-3407.