The effect of matrix polarity on the properties of poly(o-methoxyaniline)–EVA blends

Poly(o-methoxyaniline) (POMA) doped with p-toluene sulfonic acid (TSA) was successfully melt blended with ethylene vinyl acetate copolymer (EVA). The effect of the matrix polarity as well as the blend composition on the properties of the blends was investigated using two grades of EVA as matrix. The lower polarity EVA contains 8% vinyl acetate (VA) (EVA8) and the higher polarity EVA contains 33% VA (EVA33). The surface resistivity of the POMA-EVA blends was found to decrease with an increase of POMA loading. The POMA-EVA8 blends had a lower surface resistivity than POMA-EVA33 blends which is attributed to the presence of a higher proportion of conductive POMA particles in the surface region resulting from the larger polarity difference between the POMA and the EVA8 matrix. More uniform dispersion is observed from scanning electron microscopy (energy-dispersive X-ray spectroscopy) for POMA in EVA33 compared to POMA in EVA8 and this has been interpreted as being a consequence of the similar polarities between POMA and EVA33. The mechanical properties of the blends were found to be affected by both POMA loading and matrix polarity. The oxygen barrier property of the POMA-EVA blends was found to increase with POMA loading in both high and low polarity EVA matrices.