Papers by Keyword: Poly(Acrylic Acid)

Abstract: Poly(acrylic acid) (PAA) was grafted onto natural rubber (NR) to improve the compatibility of NR and poly(lactic acid) (PLA). Polymer blend between PLA and NR-g-PAA was prepared by an internal mixer. Fourier-transform infrared spectroscopy (FT-IR), tensile testing, impact testing, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were employed to determine the functional group, mechanical properties and thermal properties of blends, respectively. Results showed that the addition of NR-g-PAA significantly improved the elongation, impact strength and thermal stability of blends. The P70N30 was the optimum composition to obtain improved mechanical properties of PLA.

Abstract: The purpose of this work is to provide a comparative study of polyacrylic acid alumina (PAA/Al2O3) bulk composites with PAA/Al2O3 nano composites. This work also provides a study in the variation of glass transition temperature due to the doping of metal. Alumina nano particles were prepared using hydrothermal method. This sample was doped with Cu. Polyacrylic acid alumina nano composites were prepared using two different methods. The alumina samples were added to acrylic acid. In the first method the mixtures of acrylic acid and alumina samples were heated in oven. In the second method the same mixtures were irradiated with microwaves. The samples prepared were allowed to cool down and dried. Also the alumina bulk particles were also dispersed in acrylic acid and the similar procedure was carried out. The effect of preparation methods on the glass transition temperature of PAA/Al2O3 and PAA/Al2O3 nano composites have been studied. The glass transition temperatures Tg were determined using DSC analysis.

Abstract: Poly (acrylic acid)/montmorillonite (PAA/MMT) superabsorbent composites was synthesized by high temperature rapid-induced solvent polymerization reaction. The structure of this composites was investigated by XRD. The relationship between reaction condition and water-absorbing capacity of this composites was researched. The result shows that, when montmorillonite content is less than 5 wt%, PAA/MMT composites is nanophase materials. With the increase of cross linker, neutralization degree of acrylic acid, or montmorillonite content, water-absorbing capacity of prepared composites first rises then decreases. When cross linker content is 0.225 wt%, neutralization degree is 70%, and montmorillonite content is 5 wt%, PAA/MMT composites possess microporous structure and its water-absorbing capacity is 511 times of the solid weight itself.

Abstract: By using grafting reaction, starch-g-poly (acrylic acid) (starch-g-PAA) hydrogel was prepared and used to adsorb methylene blue (MB). Adsorption isotherm and kinetic of the sorption process were studied. Meanwhile, various thermodynamic parameters were calculated. The absorption experimental results demonstrate that the prepared starch-g-PAA is an effective adsorbent for removal of MB from aqueous solution. The adsorption of MB by starch-g-PAA is Freundlich type. Furthermore, the adsorption kinetics analyze demonstrates that the adsorption process follows the pseudo-second-order model, and the adsorption is a multi-step process. Moreover, the calculated thermodynamic parameters indicate the spontaneous and endothermic nature of the adsorption process. The values of adsorption activation energy demonstrate that the adsorption is mainly diffusion-controlled process.

Abstract: Konjac glucomannan with different molecular weights/poly(acrylic acid) hydrogels were prepared in this paper. The structure of the IPN hydrogels was characterized by FT-IR and SEM. The swelling ratio of these hydrogels showed they had pH-sensitive properties and the enzymatic degradation tests showed the hydrogels retain the enzymatic degradation character of KGM. Furthermore, hydrogel composed of native KGM degraded sharply in enzymatic degradation test and it had bigger swelling ratio and weight loss ratio than those hydrogels which composed of lower molecular weights KGM. Therefore, hydrogels composed of lower molecular weight might release drug more stable when they were used as drug carrier.

Abstract: Thiol-functionalized poly (acrylic acid)/SiO₂ (PAA/SiO₂) composite nanofiber membranes have been fabricated by a sol-gel electrospinning method and their adsorption capacity for Ag⁺, Cu²⁺ was investigated. Results showed the PAA/SiO₂ fibers had a diameter between 300 nm-700 nm. FTIR results demonstrated that the mercapto groups have been introduced into the silica skeleton. The adsorption of Ag⁺, Cu²⁺ on the membranes fit the Redlich-Peterson isotherm model best. The equilibrium adsorption capacity of Ag⁺ (575.64 mg/g) on PAA/SiO₂ nanofiber membranes is higher than Cu²⁺ (331.52 mg/g). The desorption rate reached 98% in 30 min. The removal rate of Ag⁺, Cu²⁺ still maintained above 75% after six regeneration cycles. Adsorption kinetics of Ag⁺, Cu²⁺ followed a pseudo-second-order model.

Abstract: The new electrospinning technology NanospiderTM offering a realistic potential for industrial production was used for creation of nanofiber sheets from aqueous solutions of partially neutralized poly(acrylic) acid with crosslinking agent. Produced nanofiber sheet was crosslinked by heat treatment. Absorption capacity and rate of absorption were tested and compared with superabsorbent particles and commercial superabsorbent fibers. The morphology of electrospun fibers was observed using a scanning electron microscope (SEM). Possibilities of fiber diameter influence were studied.

Abstract: The microgels with semi-interpenetrating polymer network (semi-IPN) structure based on cross-linked poly(N-isopropylacrylamide) (PNIPAM) and linear poly(acrylic acid) (PAA) were fabricated by one-step precipitation polymerization technique. The chemical composition of the microgels was determined by Fourier transformation infrared spectroscopy and elemental analysis. It was found that the PAA content inside the microgels decreased as the pH value of reaction media increased. The semi-IPN structure of the microgels was confirmed by transmission electron microscopy using uranyl acetate staining method. The pH dependent hydrodynamic diameters obtained by dynamic light scattering revealed that these microgels can reversibly shrink and swell in the pH range from 4.0 to 6.0. The semi-IPN microgels synthesized at pH 3.0 could undergo about 120 times volume change in the pH range.

Abstract: The article intends to introduce the authors’ experimental study on adsorption behaviour of chitosan and poly(acrylic acid) solution on silica by reflectometry. pH effect on adsorption-desorption of Chitosan and interaction with poly(acrylic acid) polyelectrolyte multilayer on silica has been studied. Builting multilayer formation on silica by 100ppm chitosan and 25ppm Poly(acrylic acid) solution with reflectometer. Effect of ionic strengths and molecular weight of chitosan have been discussed and we built 4 layers chitosan and 3 layers PAA and check BSA adsorption and stability. Atomic force microscopy measurement has been measured in the experiment. The results show adsorption kinetics, adsorbed mass plateau values, and reversibility of the layer formation which is typical for adsorption of strongly charged polyelectrolytes onto oppositely charged surfaces.

Abstract: The blend membranes from PAA and NR-graft-PVA were prepared. By introducing potassium persulfate (KPS) initiator, PVA can be chemically attached to the NR latex particles which was confirmed by FT-IR spectroscopy. Most of added-PVA was grafted on the NR latex particles as indicated by the almost-linear increasing of grafting percentage. The swelling of the PAA/NR-g-PVA blend membranes was performed in different concentrations of water-ethanol solutions. For the water concentration lesser than 30 vol.%, all membranes showed almost no-swelling but beyond 30 vol.% water, the degree of swelling revealed the substantial swelling with the degree of swelling increased as PAA content in the membrane increased.