An investigation on 4-aminobenzoic acid modified polyvinyl chloride/graphene oxide and PVC/graphene oxide based nanocomposite membranes

Abstract

We synthesized graphene oxide (GO) using a modified Hummer’s method, and then blended it into polyvinyl chloride (PVC) and amino-functional PVC (PVC-4ABA) matrices. GO was added to 0.5 g PVC at 0.01, 0.05, 0.1 and 0.5 g. The PVC/GO matrix was modified using 4-aminobenzoic acid (4ABA) at 0.01, 0.05, 0.1 and 0.5 g per 0.5 g PVC. This gave four amino-functional PVC/GO series and one PVC/GO series nanocomposite membranes that were prepared by a solution blending route. The filler and the modifier (4ABA) content effect on the PVC membrane properties were investigated. Fourier transform infrared spectroscopy confirmed the GO functional groups and PVC modification with 4ABA. According to scanning electron microscopy, a unique two-way layered structure was observed for modified PVC and GO composites. XRD explained the conformation of PVC/GO and modified PVC/GO nanocomposites. GO crystallite size and its interlayer distance between sheets were also studied. The XRD peak at 2θ = 10.8° with interlayer spacing of 0.81 nm was calculated with the Bragg equation. GO particle size was calculated (Scherrer formula) as 7.78 nm. XRD results revealed fine interaction between modified PVC and GO compared with unmodified PVC composites. Glass transition temperature (T_g) of non-modified PVC/GO nanocomposite was 202℃, whereas modified nanocomposite with similar GO loading had T_g equal to 212℃. Higher filler content gave better hydrophilic membranes as determined by solvent content, porosity, and shrinkage ratio. PVC-4ABA-0.5/GO 0.5 membrane with a low contact angle (25°) is a fine option for water purification. The overall results suggest that the higher modifier concentrations developed better interaction between the nanofiller and PVC.