Impact behaviour of nylon-rubber blends: 4. Effect of the coupling agent, maleic anhydride

Blends of 90 wt% nylon-6 and 10 wt% EPDM (ethylene propylene diene monomer) rubber were prepared. The rubber was grafted with various amounts of maleic anhydride (MA) with the aid of a peroxide. The initial moduli and the melt viscosities of the rubbers were only a little affected by the MA and peroxide concentrations. The effect of MA concentration on the blending process and the impact behaviour was studied. The interfacial layer was investigated using infra-red spectroscopy and elemental analysis. The MA grafted onto the rubber was found to react with the nylon during the blending process. With the MA-grafted rubbers, a much finer dispersion could be obtained. However, the concentration of the coupling agent, within the range 0.13 to 0.89 wt% grafted onto the rubber, has hardly any influence on either the dispersion process or the impact behaviour of the blends.