Papers by Keyword: Acrylic Acid

Abstract: pH-sensitive hydrogels based on chitosan-graft-poly(acrylamide-co-sodium acrylate) were synthesized via radical polymerization in solution. Ammonium persulfate was used as initiator, and various amounts of hexamine were used as a cross-linking agent. The structure of obtained hydrogels was characterized by Fourier transform infrared spectroscopy. Moisture-absorbing power of hydrogels in buffer solution with various pH value (pH = 1.65; 4.01; 12.43) was investigated. It is turned out that such a copolymers have a high moisture retention capacity (swelling index attains the value 1100%) and are capable for reusing, that makes it possible to apply the hydrogels in different areas.

Abstract: The effect of polymerization on the swelling properties of a sodium bentonite has been investigated experimentally using free swelling index (FSI). Using free radical polymerization method in cationic solution with acrylate acid as the monomer (M) and potassium persulfate as initiator (I), the optimum conditons for higher FSI value in 0.6 M NaCl solution were pH of 5.5 and I/M ratio of 0.005. The polymerized bentonite (PB) had much higher FSI values than that of untreated bentonite (UB) in deionized water and 0.6 M NaCl solution. However, in the 0.6 M CaCl₂ solution, the FSI value of PB was slightly lower than that of UB and the reason is not clear yet. The X-ray diffraction (XRD) test shows that polymer chains did not enter the interlayer of sodium bentonite crystals and it is postulated that the polymers only wrapped around the particles of the bentonite.

Abstract: In this paper, acrylic acid was grafted to chitosan in order to change the structure; polymer was obtained from modified chitosan. A series of novel toughened composite NF memebranes were prepared by over-coating the polysulfone ultrafiltration membrane with the polymer of modified chitosan. The chitosan derivatives and the polymer were characterised by infrared spectrophotometer (IR); the structure of the membrane was characrerised by scanning electron microscopy (SEM) and atomic force microscope (AFM). The composite NF membrane’s performances were strictly related to the structure of polymer. The rejection of the membrane was 96.3% with flux as high as 386.46 L m^-2 h^-1 with the 1000 mg/L of NaCl. Tensile strength of membrane increased 46%. The HCl (5%) resistance increased from 20.3 to 36.8h. The NaOH (5%) resistance increased from 18.3 to 31.6h. These results indicated the prepared toughened composite NF memebrane was excellent NF membrane, which had a wide application prospect.

Abstract: A series of superabsorbent polymer composites (SAPCs) were synthesized via emulsion polymerization of partially neutralized acrylic acid onto polystyrene in the presence of Hectorite (HT) clay powder and mung bean starch (MBSt) using Ammonium Persulphate and N’N,-Methylenebisacrylamide as initiator and crosslinker, respectively. The aim of this study is to prepare a hydrogel composite using Hectorite clay as the reinforcement and to study the effect of Hectorite clay on the thermal properties of the composite. FTIR analysis confirmed that the grafting polymerization took place among acrylic acid, polystyrene, mung bean starch and Hectorite clay. From DSC ad TGA analysis, the glass transition temperature (T_g) increased and the weight loss of the composite reduced upon incorporation of Hectorite clay.

Abstract: Shellac is a natural product which has been presumed as a fragile polymer due to itschemical properties. The objective of this study was to improve chemical properties of shellac by themodification with different concentration of glycerol and acrylic acid. Shellac was reacted withglycerol at various temperature and amounts of glycerol. The intermediate product was reacted withacrylic acid at different concentration. Acid value, hydroxyl groups, and free glycerol concentrationof modified shellac was determined. The result showed that acid value gradually decrease alongincreasing temperature for each ratio of glycerol and acrylic acid to shellac. The concentration ofhydroxyl groups rise as temperature and ratio increases. Furthermore, free glycerol concentration felldown along with the rise temperature. Modification chemical properties of shellac with glycerol andacrylic acid can be applied for the further study to enhance shellac properties.

Abstract: This study aims to explore modification of polyaniline nanofiber through grafting polymerization to increase its solubility and processability for application in aqueous environment. Grafting via electron beam radiation procedure is extremely productive in terms of time consumption and environmental friendliness. In this work, acrylic acid was grafted on to polyaniline nanofiber using electron beam irradiation. The influence of altering the electron beam power from 2-3 MeV, radiation dosage from 5-25 kGy, acrylic acid concentration from 10-100% and soaking time from 2-24 hours during graft polymerization were studied over the grafting percentage (%G). Grafting parameter was determined by weight changes before and after grafting procedure. Grafted polyaniline is characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA). Formation of new peak at 1700 cm-1 for FTIR spectroscopy analysis of grafted polyaniline confirmed grafting has taken place during irradiation.

Abstract: In order to explore a smart carrier which can control drug delivery in special pH environment, a type of nanometer material, namely, poly acrylic acid acrylamide (P(AA-AM)) was synthesized with acrylic acid and acrylamide as monomers. Its structure was determined using Fourier transform infrared spectroscopy (FTIR) and its swelling properties were tested by measuring its weight evolution. The drug delivery control potential was estimated by monitoring its swelling performances in the solutions of different pH values. The cycle characteristics were also investigated to determine its degradation properties in the environment. The results indicate that the synthesized material is sensitive to pH and is suitable for controlling drug delivery at the pH range from 10 to11 and below 7. Furthermore, this material can be automatic decomposition in the environment so that it is a degradable green material without causing burden to the environment.

Abstract: A novel starch-g-poly (acrylic acid) hydrogel was prepared by graft-copolymerization among starch, acrylic acid in aqueous solution with potassium persulfate as an initiator, N, N-methylenebisacrylamide as a crosslinking agent. Characterization of the graft copolymer was carried out by X-ray diffraction, FTIR and SEM analytical methods. Swelling kinetic analysis in distilled water was done to study the swelling behavior of the product. The results show that the product exhibits water absorption of 786g/g in distilled water at ambient temperature. It has been proved that the grafting of acrylic acid onto starch was successful and the aggregation of phase of native starch was changed from semi-crystalline state to amorphous aggregation state due to copolymerization.

Abstract: This paper presents the development of silver nanoparticles entrapped starch-polyacrylic acid hydrogel by a one step facile strategy. Formation of silver nanoparticles was confirmed by TEM and SPRE. Hydrogen bond interaction present in the hydrogel network was manifested from the FTIR spectroscopy. Silver nanoparticles in the face centred cubic lattice were confirmed by XRD. Visco-elastic properties studied by rheological analysis showed storage modulus of ~1500 Pa and exhibited a high storage modulus than loss modulus revealing the formation of strong gels. Phase transition temperature was confirmed by DSC. Antimicrobial screening studies of these hybrid gel exhibited antimicrobial activity to E.coli and S.aureus suggesting its applications for gram + ve and gram - ve bacteria.

Abstract: Has successfully created an optimum composite of rPP/DVB/PP-AA/comBen+ZB based on the mechanical and fuel resistance properties. The starting material recycled PP (rPP), PP modified acrylic acid (AA) as coupling agent (PP-AA), crosslinker divinylbenzene (DVB), 20 phr of commercial bentonite (comBen) and 5 phr of zinc borate (ZB), was reactivelly processed in xylene. Composites analysis using XRD presented that the bentonite had been exfoliated inside of PP matrix. Test results showed that both of tensile strength (TS) and young's modulus (YM) of rPP/DVB/PP-AA/comBen+ZB composites following ASTM D638 was increased. The testing results of burning rate (BR) of composite rPP/DVB/PP-AA/comBen+ZB according to ASTM D635 decreased. The presence of bentonite as a natural fire retardant and ZB as fire retardant additive on composite rPP/DVB/PP-AA/comBen+ZB able to increase mechanical properties and also improving the flammability resistance.