(448c) Compatibilizing Effect of Epm-G-Ma in Sorona®/Epdm Incompatible Blends

The morphology and properties of immiscible and highly incompatible blends of Sorona^® [poly (trimethylene terephthalate)] and EPDM blends has been studied with and without the addition of a compatibilizer precursor EPM-g-MA. These incompatible blends are characterized by a two-phase morphology, narrow interphase, and poor physical and chemical interactions across the phase boundaries. Therefore a reactive route was employed to compatibilize these blends by the addition of maleic anhydride grafted ethylene propylene rubber (EPM-g-MA). The influence of EPM-g-MA on the phase morphology was studied quantitatively by scanning electron microscopy (SEM). It was found that the addition of EPM-g-MA reduces the domain size of the dispersed phase followed by a leveling off at higher concentrations of the compatibilizer. This is an indication of interfacial saturation. The experimental compatibilization results were compared with theoretical predictions. Free volume measurements using positron annihilation lifetime spectroscopy (PALS) were done to analyze the interaction of blends. In the case of uncompatibilized blends the free volume values tend to increase by the addition of EPDM phase showing high level of incompatibility. Addition of EPM-g-MA to the blends tends to decrease the free volume showing its compatibilizing effect.

Key words: Sorona^®, Morphology, Compatibilizer, Scanning electron microscopy (SEM), Positron annihilation lifetime spectroscopy (PALS).