Extended Investigation on the Delicate Correlations Between Thermal Behavior and Physical Characteristics of Multi-component Blends

Abstract

Polypropylene (PP)/polyamide6 (PA6)/ethylene propylene diene rubber (EPDM) (70/15/15) ternary polymer blends compatibilized with maleic anhydride-grafted EPDM (EPDM-g-MA) were prepared under various processing parameters (barrel temperature, screw speed, and blending sequence). Thermal studies on the prepared blend samples were carried out using differential scanning calorimetry and dynamic mechanical thermal analysis. According to the results, heterogeneous nucleation phenomenon was observed due to the solidification of the PA6 particles dispersed within the PP melt leading to a significant increase in the crystallinity degree and exotherm crystallization peak temperature of PP compared to the pure homopolymer. This was suppressed in the samples with core–shell morphology due to the reduced PP/PA6 interfacial contact. Fractionated crystallization was observed when PA6 droplets dispersed too fine within the matrix (in this case $\bar{d}_M\sim 0.3\,\upmu \hbox {m}$). Scanning electron microscopy micrographs were consistent with the melting and crystallization behavior of the blend samples.