Thermoplastic elastomeric blends of nylon-6/acrylate rubber: Influence of interaction on mechanical and dynamic mechanical thermal properties

Nylon-6 and acrylate rubber (ACM) were melt blended in a Brabender Plasticorder at 220 degrees C and 40 rpm rotor speed. The reactive nature of the blend is reflected in the mixing torque behavior of the blends at different compositions. The solubility characteristics of the blends in formic acid solution gives an approximate idea of the amount of nylon-6 grafted onto ACM and vice-versa. A reaction mechanism is proposed based on the well known epoxy-amine and epoxy-acid reactions and is confirmed by infrared spectroscopic studies of the blends. The influence of interaction between the two polymers on the mechanical and the dynamic mechanical properties of the blends is analyzed in detail, and the results are interpreted on the basis of the formation of nylon-ACM graft copolymer at the interfaces. The dynamic mechanical thermal analysis (DMTA) reveals a two phase morphological structure, indicating incompatibility of the blend components. The grafting reaction results in dramatic increase in both the storage modulus and the Young's modulus of blends. The presence of grafted rubber chains is reflected in the secondary transition of the rubber loss peak at higher temperature. Also, a substantial improvement in the damping properties of the blends in the service temperature range (i.e., 25 to 175 degrees C) is revealed from the DMTA results. The dynamic vulcanization of the ACM phase during melt mixing improves the elongation at break values of the blends.