Melt rheology of ethylene ionomers blended with a small-molecule acid

A novel EMAA ionomers with the incorporation of low molecular weight carboxylic acid have been developed to reduce melt rheology without changing the complete transparency of ionomers. Here, a blend of EMAA-59Zn (93 wt%) and montanic acid (MA, C27H55COOH, 7 wt%) was investigated in terms of TGA, DSC, FT-IR, and dynamic shear viscosity. A good heat stability of MA during melt blending preparation and melt viscosity measurement was confirmed by TGA. DSC showed only one peak (86.9°C) for the blend sample, and FT-IR exhibited additional peaks (1545, 1625 cm−1) by the blending. These facts suggested that the blend is a homogeneous mixture and the blend induced an additional new coordination structure between Zn and carboxylic acid. Dynamic melt rheological measurement exhibited a significant decrease of storage modulus and loss modulus by the blending. The reduction of melt rheology was more than the addition of plasticizing effect and the decrease of neutralization. The newly induced coordination structure implies a relationship with the unexpected additional reductions.