Iranian Journal of Chemical Engineering (IJChE)

Abstract The aim of this study was to improve the adhesion performance of plasticized polyvinyl chloride (PVC) coatings on steel substrates by using nanoparticles. For this purpose, the PVC plastisol with different concentration of nano-silica was prepared and applied to bond steel joints. The adhesive strength of the joints was determined by single-lap shear test. Moreover, mechanical properties and microstructure of coating were investigated. The addition of 1wt% nano-silica to plastisol dramatically increased the lap shear strength up to 4-fold, which was an outcome of compatibilizing effect of silica. Young's modulus and tensile strength of plasticized PVC were slightly increased by adding nanoparticles, as well. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) exhibited higher inclusion size in the coating having higher silica volume which was attributed to the agglomeration of nanoparticles. In the following, the effect of plasticizer composition on the adhesion strength by replacing some part of dioctyl phthalate (DOP) plasticizer with more polar oil, epoxidized soybean oil (ESO), was examined. Although adding ESO improved the lap shear strength of the neat coating, its effect on the properties of the coatings containing silica was negligible.

Abstract Polysulfone/carbon nanotubes (PSF/CNTs) nanocomposite membrane was prepared via phase inversion induced by immersion precipitation technique. In addition, the surface of the CNTs were functionalized by polar carboxylic and amine groups to improve the interaction between the CNTs and the polymer matrix. For this purpose, the neat CNTs were chemically treated using sulfuric acid/ nitric acid (H2SO4/HNO3) mixture and an aromatic amine agent, i.e. 1-4-diamino benzene (DABZ), to produce the functional groups on the CNTs surface. The Fourier transform infrared (FTIR) spectra indicated the presence of carboxylic- and amine-functional groups on the nanotubes surface. Asymmetric PSF composite membrane with various levels of the functionalized CNTs were prepared to investigate the effect of functional group type on the morphology and water flux rate of the resulting membranes. The results showed that the incorporation of the functionalized CNTs up to 0.5 wt% increased the pore size and surface roughness of the sheet membranes, while further addition decreased porosity and roughness. Higher water flux rate was observed for the amine-functionalized CNTs (af-CNTs) reinforced PSF membrane when compared with the membranes reinforced with the carboxyl-functionalized CNTs (cf-CNTs). The stronger compatibility between af-CNTs and the PSF matrix caused higher water permeability. The salt rejection performance of these microfiltration composite membranes was evaluated.

Abstract Poly (vinyl alcohol) (PVA) nanofibers were prepared via electrospinning of concentrated PVA solutions. The nanofibers were crosslinked to enhance their resistance against the moisture. The chemical crosslinking of the nanofibers was carried out using glutaraldehyde as crosslinking agent in the presence of hydrochloride acid. The chemical structure, water solubility, and morphology of the electrospun PVA nanofibers were characterized by Fourier transform infrared (FTIR)
spectrometer,water durability test, and scanning electron microscope (SEM), respectively. In addition, the crosslinked nanofibers were coated by copper nanoparticles (CNPs) using electrospraying technique. For this purpose, colloidal CNPs were synthesized through the chemical reduction of copper ions in the presence of different stabilizers, i.e. poly (vinyl alcohol) and ethylene glycol (EG), in an aqueous media. The effect of the stabilizer concentration (0.001 and 0.005 M) and reduction temperature (25 and 70°C) were investigated on the CNP dispersion in the media using UV-visible spectroscopy. Furthermore, the dispersion of the CNPs on the PVA nanofibers was studied by means of SEM. The SEM micrographs showed that the nanofiber scould properly imprison the CNPs. Successful the proposed approach would be exploited to prepare polymer nanofibers incorporating metal nanoparticles which might have interesting properties such as antibacterial activity.

Abstract Polyurea microcapsules containing an active agent, i.e. ethion as pesticide, have been prepared by interfacial polymerization between 2, 4-toluene diisocyanate (TDI) and diethylenetriamine (DETA) in an oil-in-water (O/W) emulsion system. The effects of the nature of the emulsifier, the monomer weight ratio, and a novel promoter, i.e. potassium phthalimide-N-oxyl (PPINO), on the morphology, microstructure, and thermal stability of the microcapsules have been investigated. PPINO was used as a water-soluble promoter capable of dimerizing and trimerizing the isocyanate reactant
in the interfacial polymerization. The transmission electron microscopy (TEM) micrographs showed that the addition of the promoter had no significant effect on the microcapsule shell thickness. Increasing the amount of PPINO caused the degree of crystallinity of the polymer shell to decrease considerably. In addition, increasing the amount of promoter up to 2 wt% caused the thermal stability of the microcapsules to decrease, while using promoter beyond this level resulted in higher thermal stability.