Papers by Keyword: Polyacrylic Acid

Abstract: The potential of polyacrylic acid (PAA) nanofiber prepared by the electrospinning technique for the humic acid (HA) adsorption from aqueous solution was investigated. In this study, the adsorption experiments were carried out to investigate the effect of temperatures in a batch system. From experiment it can be seen that the HA adsorption using PAA nanofiber increased with increasing temperature. Thermodynamic parameters data indicated that the HA adsorption process was non-spontaneous and endothermic under the experimental conditions, with the Gibbs free energy (∆G^o) in the range of 1.721-0.980 kJ mol^-1, enthalpy (∆H^o) and entropy (∆S^o) of 7.24 kJ mol^-1 and 18.52 J mol^-1 K^-1, respectively.

Abstract: This article reports the synthesis of engineered materials i.e. composite materials based on matrix (polymeric polyacrylic acid) and reinforcement (organic clay) through 6-hour and 12-hour ultrasonication at different intervals. All the precursors and desired composite materials were characterized by Fourier transform infra-red (FT-IR) and scanning electron microscopy (SEM) techniques. The disappearance of Si-O characteristic peak after ultrasonication justifies the fabrication and incorporation of organoclay in the polymeric structure of polyacrylic acid as revealed by FT-IR analysis. The SEM images interpreted the surface morphology, porosity, distribution and compatibility of matrix and reinforcement in it, which has been achieved successfully in this study for exfoliation form.

Abstract: Polyacrylic acid/attapulgite (PAA/ATP) composite hydrogels used for removal of heavy metal ions from aqueous solution was synthesized via radical polymerization with acrylic acid (AA) and attapulgite (ATP) modified by hydrochloric acid as adsorbent. Chemical composition of the modified ATP was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) and the morphology of the PAA/ATP hydrogels was characterized by scanning electron microscope (SEM), respectively. The swelling ratio, pH-sensitivity and adsorption performance of Ni (II) ions of the composite hydrogels were studied. The results showed the swelling ratio of the PAA/ATP composite hydrogels was higher than that of PAA hydrogels and the composite hydrogels displayed sensitivity to pH values with a sharp increase of swelling ratio when the pH values increased from 4 to 6. Comparing with PAA hydrogels, the composite hydrogels obtained a larger adsorption capacity of Ni (II) ions, the average adsorption capacity could reach 72.8 mg/g and adsorption ratio could reach 84%.

Abstract: A microwave assisted precipitation method has been used for the synthesis of ZnO nanorods by reacting zinc nitrate hexahydrate and sodium hydroxide. Polyacrylic acid (PAA) uses as a polymeric additive in process. The synthesized ZnO is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser light scattering technique. It is found that ZnO nanorods exhibit a crystalline structure with hexagonal structure of the wurtzite. Primary size of the synthesized ZnO nanorods can be controlled by PAA concentrations. Increasing of PAA concentrations provide ZnO nanorods with smaller and shorter size.

Abstract: Agriculture biomasses have been successfully converted into value-added products such as biocomposite plastics, furniture, papers and textiles. However, only the cellulose parts of these lignocellulosic materials are being used while other components such as lignin and wax are discarded. For a tropical country like Malaysia, banana stem is one of the sources of biomasses. Like other biomasses-based products, only cellulose part of banana stem is used while the lignin portion is discarded due to overly hydrophilic character. This water-loving property of lignin can be manipulated into specific application such as water absorbent for waste treatment. This research is aimed to synthesis water absorbent-based lignin from banana stem. The lignin had been extracted from banana stem using Kraft process prior to grafted with acrylic acid monomer (AA) in order to increase its water absorbency. The reaction was carried out via free radical polymerization in the presence of hydrogen peroxide (H₂O₂) as initiator and ammonium iron (II) sulfate hexahydrate as catalyst. The reaction temperature was set at 60°C. Grafting efficiency of polyacrylic acid (PAA) onto lignin backbone was determined by varying the amounts of AA monomer, lignin and initiator. The highest grafting percentage was acquired at 60% with the amount of 6ml acrylic acid, 2ml initiator and 0.2g lignin respectively.

Abstract: The design of layers for multilayer flame-resistant glass is a vital task in terms of upgrading fire resistance of window glass units. This paper describes chemical modification of flame-proof acrylate hydrogel layers and shows experimentally how a cross-linking agent — hexamethoxymethylmelamine ether – influences the kinetics of hydrogel polymerization and the enhancement of carbonated structures yield. It has been determined that adding HMMM to the hydrogel composition raises the coke residue yield from 10 % to 35 % and increases the 19 mm thick glass flame resistance class from EI30 to EI50.

Abstract: A novel polyacrylic acid /xanthan gum/bentonite superabsorbent polymer (SAP) was prepared through chemical crosslinking by a polymerization technique in a complete aqueous environment. This SAP was fabricated effectively by dispersing xanthan gum (XG) and bentonite in a monomeric solution, using N,N’-methylenebisacrylamide as crosslinker and ammonium persulfate as initiator. Fourier transform infrared (FTIR) spectral analysis showed that graft copolymerization reaction took place between acrylic acid (AA), XG and bentonite. The optimal process conditions of preparing SAP were investigated. Results showed that the relevant SAP had maximal salt-water absorption (98g/g) when mass ratio of m (bentonite):m (AA) was 5:1, m (ammonium persulfate):m (AA) was 1.75×10^-4, m (N,N’-methylenebisacrylamide):m (AA) was 3×10^-4, m (XG) :m (AA) was 1:5, the neutralization degree of AA was 75%. Bentonite can not only effectively increase water absorbency, but also improve water retention ability.

Abstract: In this article we provide results on the preparation of starch-based block copolymer with polyacrylic acid by radical polymerization. Starch was pregelatinized and then reacted with acrylic acid in the presence of radical polymerization initiator. Resulting mixture was used to prepare cast-films. Structure of the polymer films was investigated by gel filtration chromatography, FTIR and DCS analysis. It was found that structure of the films represents starch-graft-polyacrylic acid dispersed in a starch matrix. Results of DCS and FTIR suggested that polyacrylic acid acts as additional plasticizer for starch films.

Abstract: The acid dissociation equilibria of typical linear weak acid polyelectrolytes, polyacrylic acid (PAA), were investigated by a potentiometric titration method. The electrostatic effects on the equilibria have been rationalized based on a Gibbs-Donnan concept. The apparent acid dissociation constant of PAA at completely neutralized condition determined by extrapolation are quite close to acid dissociation constant of their monomeric acid. The effective volume and the radius of polyelectrolyte phase of PAA have been calculated experimentally by the non-ideality term of ΔpK values with an iterative procedure. The radiuses increase with increasing at α 0.2 region. It is attributable to the repulsion between negatively charged carboxylate groups is weak at lowly dissociated state, whereas the repulsion is strong in highly dissociated state.

Abstract: The synthesis and characterization of nickel-based aerogel prepared using nickel chloride as the precursor via sol-gel method is described. The addition of the polyacrylic acid as an template to the solution of NiCl2•6H2O can guide the gelation in the reaction to build a three dimensional open structure. The aerogel has been characterized using field emission scanning electron microscopy (FESEM), highresolution transmission electron microscopy (HRTEM), nitrogen adsorption desorption analysis and powder X-ray diffraction (XRD). The results indicate that the nickel-based aerogel has a typical three dimensional structure made up of spherical particles with an open porous network and has high surface area about 192 m2/g, average pore diameter about 40nm. The X-ray diffraction (XRD) patterns show that the aerogel prepared at room temperature belongs to amorphous material. The synthesis of nickel-based aerogel, using polyacrylic acid as an template, is especially unique in our experiment.