Polypropylene/polyethylene terephthalate blends compatibilized through functionalization

Abstract

Abstract In attempts to improve the compatibility of polypropylene with polyethylene terephthalate, an acrylic acid functionalized polypropylene was evaluated as the blend component in polyblends containing 40 percent by weight polyethylene terephthalate and compared with an unmodified polypropylene. The preliminary experiments in a batch laboratory mixer were followed by compounding in a co‐rotating twin‐screw extruder. Additives such as magnesium acetate and p‐toluenesulfonic acid were evaluated as catalysts for potential interchange or esterification reactions that could occur in the melt. The blends were characterized through scanning electron microscopy, infrared spectroscopy, differential scanning calorimetry, and for mechanical properties. The results show that the functionalized polypropylene promotes a fine dispersed phase morphology, improves processability and mechanical properties, and modifies the crystallization behavior of the polyester component. These effects are attributed to enhanced phase interactions resulting in reduced interfacial tension (calculated as a 4‐fold decrease). The presence of the additives does not, in general, improve any further the blend morphology and properties, or its processability.