Optimizing the surface modification of cohesive polyethylene powders in a vibrated plasma-spouted bed: Exploring agglomerate size impact on coarser particle addition mechanism

Abstract

Ultrafine polymer powders have garnered attention owing to their superior physical properties and reactivity. Nonetheless, the cohesive nature of these powders notably impedes efficient plasma surface modification, thereby limiting potential applications. The effects of optimizing the fluidization of cohesive powders on plasma treatment within a plasma-spouted bed were investigated in a prior study, wherein surface modification was significantly improved by incorporating coarser particles and vibration. However, the optimal conditions and mechanisms by which adding coarser particles to a vibrated plasma-spouted bed contributes to this enhancement remain unelucidated. This study entailed an investigation of the influence of gas flow rate, agglomerate properties, and plasma distribution in optimizing the wettability modification of ultrafine powders. Results indicate that increased gas flow rate, coarser particle size, and quantity lead to the formation of smaller, more uniform-sized agglomerates. Furthermore, the contact angle of the treated powder demonstrated a linear decrease with the reduction of average agglomerate size within a suitable gas velocity range, suggesting that enhanced exposure of the powder surface to plasma contributes to the optimization of plasma treatment. However, high-gas velocity may trigger particle entrainment and diminish surface modification, as evidenced by the limited plasma distribution primarily at the bottom of the reactor.