POLYVINYL CHLORIDE MEMBRANES GRAFTING WITH POLYACRYLIC ACID VIA AR-PLASMA TREATMENT

Abstract

This work explores the synthesis and properties alteration of new composite membrane system based on polyvinyl chloride (PVC) grafting with polyacrylic acid (PAA) using argon (Ar) plasma. The membranes of PVC were synthesized by solution-casting method, where PAA was deposited onto PVC using dielectric barrier discharge (DBD) at atmospheric pressure with different carrier gases such as (O2, Ar, N2, air) to get the optimum condition for grafting process of acrylic acid. Physicochemical properties were investigated as function of varied carrier gas for grafting process of PAA. ATR-FTIR has provided information on details of chemical structure of membrane, while morphological changes are characterized by scanning electron microscope (SEM). Moreover, mechanical properties of the membranes were studied using tensile strength (TS). Surprising, the wettability behavior of modified PVC membrane with AA vapor (plasma polymerization) is closed to such membranes those treated with O2 plasma-AA liquid. An ultra-thin, pin hole free films of PAA were deposited onto PVC membranes leading to the increase of the wettability feature of the membranes. Meanwhile, ion exchange capacity (IEC) of such membranes was investigated by volumetric method and it is directly dependent on the electrochemical properties of membranes. The IEC values in case of grafting with PAA in vapor phase are promising and maybe related to the special structure of plasma deposited polymers. The grows in the electronegativity of the grafted and sulfonated membranes is an indication to the proton permeability. Therefore, such membranes may be used as polyelectrolyte membranes (PEM) in direct methanol fuel cell (DMFC).