Rheological and thermal investigation of blends of ionically cross-linked and un-modified polypropylene and preparation of carbon black-based electromagnetic wave shielding composites

Abstract

Initially, blends of ionically cross-linked PP (icPP) and unmodified PP were prepared. The miscibility and morphologies of the blends were studied with thermal and rheological analyses. It was confirmed that the blends were immiscible and formed co-continuous morphologies at icPP contents higher than 57.5 wt%. The formation of an inter-phase with synergistic properties was confirmed. Subsequently, CB incorporated to the blend composition with co-continuous morphology at 82.5 wt% icPP. Three strategies were implemented to hamper CB migration from unmodified PP to icPP phase during blending. A DC conductivity of 7.68 × 10-5 S cm⁻¹ was achieved at 2.625 wt% CB, which was close to the conductivity of unmodified PP with 12.5 wt% CB. The samples were tested for EMI shielding properties in the microwave frequency region. A minimum RL of −23.14 dB was obtained. SEM imaging confirmed the co-continuous morphology for the blended samples with CB and the localization of CB particles.