Cold Plasma Modification Effects on the Water Flow through Sintered UHMWPE Membranes

Abstract

The effects of cold plasma surface modification on the pore size and permeated water flow through sintered UHMWPE membranes were investigated. Two different UHMWPE, having the same average particle size (180 µm) but different molecular weights (3 × 108 and 7 × 108 g/mol) were used to manufacture the membranes. The membranes were sintered at 200°C at varying sintering times (60, 75 and 90 minutes), and were characterized by SEM, contact angle and permeated water flow rate. Surface modification was performed with the application of methane plasma for 60 min. For the untreated membranes, increased sintering times led to flow reduction, and this behavior was more significant for the membrane manufactured with the lower molecular weight polymer. These results were associated with pore size reduction and increased compaction of the samples sintered for longer times. Plasma surface modification led to significant water flow reduction through the membranes. A 90% flow decrease was measured for the membranes manufactured with the higher molecular weight polymer, sintered for 60 minutes. This behavior was attributed to higher surface tension on the walls, lowering the permeate water flow rate. SEM analysis and contact angle measurements showed plasma modification to successfully modify membrane surface characteristics and likely to promote pore size reduction.