Compatibilizer-induced microstructural changes in poly(trimethylene terephthalate)EPDM blends studied by the positron annihilation lifetime technique and differential scanning calorimetry

Abstract Blends of poly(trimethylene terephthalate) (PTT) and ethylene propylene diene monomer (EPDM) with and without the compatibilizer poly (EPM-graft-MA) were investigated by positron annihilation lifetime spectroscopy (PALS) and differential scanning calorimetric (DSC) measurements. The DSC results for the blend with 50/50 composition revealed two glass transition temperatures, indicating a two-phase system. In the presence of compatibilizer, the two glass transition temperatures shifts towards each other, suggesting an increased interaction between the blend components. The PALS results for the blends without compatibilizer showed an increase in free volume hole size and concentration with increasing EPDM content in the blend, suggesting the coalescence of free volumes of EPDM with the PTT to some extent, but the phase-separation behaviour continued. The free volume of these blends exhibited positive deviation from the known free volume linear additivity rule. However, poly(EPM-graft-MA) compatibilized blends of PTT/EPDM had a noticeable decrease in the free volume parameters, which was clearly due to the compatibilizing effect through increased interaction between blend components. Copyright © 2005 Society of Chemical Industr