Metal ion retention properties of water‐insoluble polymers containing carboxylic acid groups

Crosslinked poly(acrylic acid), PAA, and poly(2‐acrylamidoglycolic acid), PAAG, were synthesized by radical polymerization. Both resins contain carboxylic acid groups. PAA at basic pH exists basically as an acrylate anion and PAAG shows three atoms or groups, carboxylic acid, hydroxyl, and amide groups, that can act as ion exchanger or chelating groups. Both resins are studied as adsorbents to trace metal ions from saline aqueous solutions and natural sea water and their properties by Batch equilibrium procedure are compared. The metal ions studied under competitive and noncompetitive conditions were Cu(II), Pb(II), Cd(II), and Ni(II). The effects of pH, time of contact, amount of resin, temperature, and salinity were studied. Resin PAA shows a high affinity (>80%) for Cu(II) and Cd(II) and resin PAAG shows also a high affinity for Ni(II), Pb(II), and Cd(II). By treatment of the metal ion‐loaded resin with 4M HNO₃ it is possible to recover completely the Cu(II) ions from resin PAA and Ni(II) and Pb(II) from resin PAAG. The metal ion retention properties were studied with natural sea water. For those natural sea waters containing Cu(II) and Cd(II), the resins showed a high affinity for Cd(II) ions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 697–705, 2006     

Synthesis and properties of chitosan‐modified poly(acrylic acid)

Potassium persulfate (K₂S₂O₈) was used to initiate the polymerization of acrylic acid (AA) monomer in a chitosan (CS) solution. Both a poly(acrylic acid) (PAA) homopolymer and a CS‐co‐PAA copolymer were produced. When the amount of AA was increased from 5 to 40 g with 5 g of CS, the total monomer conversion was found to increase from 89 to 98% after 2 h of reaction at 70°C. In addition, the percentage of reacted AA monomer being converted to the CS‐co‐PAA copolymer (copolymerization efficiency) and the weight composition of the PAA portion in the copolymer (copolymer composition) both increased with the amount of AA added. The structures and properties of the synthesized CS‐modified PAA polymers were studied. In Fourier transform infrared spectra, the formation of a polyelectrolyte complex between CS chains and PAA chains could be observed. From the thermograms obtained via differential scanning calorimetry, we found that the presence of rigid CS chains increased the glass‐transition temperature of PAA. Thermogravimetric analysis revealed three stages of degradation of the synthesized CS‐modified PAA polymers. The swelling ratio of the CS‐modified PAA polymers depended on the pH value and had a maximum value in a buffer solution at pH 7. This was due to the changes in the morphological structure with the pH value. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Trace metal ion retention properties of crosslinked poly(4‐vinylpyridine) and poly(acrylic acid)

The crosslinked resins poly(4‐vinylpiridine) (PVPy) and poly(acrylic acid) (PAA) were obtained by radical polymerization. PVPy shows monodentate ligands and PAA at basic pH is basically as acrylate anion, which can contain end‐carboxylates groups or form a bridge acting as mono‐ or bidentate ligands. The retention properties for trace metal ions from saline aqueous solutions and natural seawaters of these two resins were investigated by Batch equilibrium procedure. The metal ions studied were Cu(II), Pb(II), Cd(II), and Ni(II). The following effects were studied: pH, contact time, amount of the adsorbent, temperature, and salinity. The resin PVPy showed a high affinity for Cd(II) and PAA for Cu(II) and Cd(II). The metal ions were determined in the filtrate by atomic absorption spectrometry. By the treatment of the loaded resin with 4M HNO₃, it was possible to remove completely the Cu(II) ions. The retention properties of the resins were studied for trace metal ions present in the natural seawaters. Both resins showed a high affinity for Cd(II) when the natural seawater contained Cu(II) and Cd(II). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2908–2916, 2004     

Metal ion retention properties of poly(acrylic acid) and poly[N‐3‐(dimethylamino)propyl acrylamide‐co‐acrylic acid]

The crosslinked resins poly(acrylic acid) (PAA) and poly[N‐3‐(dimethylamino)propyl acrylamide‐co‐acrylic acid] [P(NDAPA‐co‐AA)] are obtained by radical polymerization and characterized by FTIR spectroscopy. PAA at basic pH exists basically as an acrylate anion that may contain end carboxylate groups or form bridges acting as mono‐ or bidentate ligands. P(NDAPA‐co‐AA) presents three potential ligand groups in its structure: carboxylic acid, amide, and amine. The trace metal ion retention properties of these two resins is compared by using the batch equilibrium procedure. The metal ions are contained in saline aqueous solutions and are found in natural seawater. The retention of Cu(II), Pb(II), Cd(II), and Ni(II) metal ions is studied under competitive and noncompetitive conditions. The effects on the pH, contact time, amount of adsorbent, temperature, and salinity are investigated. The PAA resin presents a high affinity (>80%) for Cu(II) and Cd(II) ions. The P(NDAPA‐co‐AA) resin shows a high affinity for Pb(II) and Cd(II) ions. With 4M HNO₃ it is possible to completely recover the PAA resin charged with Cu(II) ions and the P(NDAPA‐co‐AA) resin charged with Pb(II) ions. The two resins show a high affinity for Cd(II) ions from the seawater containing Cu(II) and Cd(II) ions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1385–1394, 2005     

pH/Temperature control of interpolymer complexation between poly(acrylic acid) and weak polybases in aqueous solutions

The formation of interpolymer complexes (IPC) between poly(acrylic acid) (PAA) and poly(acrylamide) (PAM), poly(N,N-dimethylacrylamide) (PDMA), and statistical copolymers of acrylamide (AM) and N,N-dimethylacrylamide (DMA) has been studied as a function of pH, salt concentration and temperature (0–70 °C). The cloud points of dilute solutions were measured by turbidimetry and phase diagrams were determined as a function of temperature and pH in pure water and as a function of pH and salt concentration at room temperature. For each temperature and salt concentration a critical pH (pH_crit) below which IPC are observed was defined. In the case of PAA/PAM, pH_crit continuously decreased with increasing temperature, from pH 3.5 at 0 °C to pH 1.9 at 60 °C (UCST-type). In the case of PAA/PDMA, pH_crit, increased with temperature. The LCST-type behavior of the hydrogen-bonding complex formed between PAA and PDMA was attributed to the dimethyl substitution of amide groups that puts in hydrophobic interactions at high temperature. PAA and statistical copolymers P(AM-co-DMA) showed an intermediate behavior between PAA/PAM and PAA/PDMA with a continuous shift from UCST-type to LCST-type with increasing amount of DMA. This behavior can be attributed to changes in configurational entropy due to the IPC formation and (for PDMA) to the release of water molecules initially confined in hydrophobic hydration cages around DMA units. While at low salt concentration, the stability of PAA/PAM and PAA/PDMA complexes only slightly increases with the screening of ionized acrylic units, there is a sharp increase of pH_crit at high salt concentration in relation with the weakening of the solvent quality. In this regime, the complex formation of PAA/PDMA is greatly enhanced compared to PAA/PAM due to the interference of hydrophobic interactions.     

Fluconazole release through semi‐interpenetrating polymer network hydrogels based on chitosan,acrylic acid,and citraconic acid

Semi‐interpenetrating polymer network hydrogels with different compositions of chitosan (Cs), acrylic acid, and citraconic acid were synthesized via free‐radical polymerization with ethylene glycol dimethacrylate as a crosslinker. The variations of the swelling percentages of the hydrogels with time, temperature, and pH were determined, and Cs–poly(acrylic acid) (PAA) hydrogels were found to be most swollen at pH 7.4 and 37°C. Scanning electron micrographs of Cs–PAA and Cs–P(AA‐co‐CA)‐1 (Cs‐poly(acrylicacid‐co‐citraconir acid)^?1) were taken to observe the morphological differences in the hydrogels. Although the less swollen hydrogel, Cs–P(AA‐co‐CA)‐1, had a sponge‐type structure, the most swollen hydrogel, Cs–PAA, displayed a uniform porous appearance. Fluconazole was entrapped in Cs–P(AA‐co‐CA)‐1 and Cs–PAA hydrogels, and the release was investigated at pH 4.0 and 37°C. The kinetic release parameters of the hydrogels (the gel characteristic constant and the swelling exponent) were calculated, and non‐Fickian diffusion was established for Cs–PAA, which released fluconazole much more slowly than the Cs–P(AA‐co‐CA)‐1 hydrogel. A therapeutic range was reached at close to 1 h for both hydrogels. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Storage modulus changes with temperature in poly(vinyl alcohol), PVA,/poly(acrylic acid), PAA, blends

Summary Poly(vinyl alcohol), PVA, and poly(acrylic acid), PAA, blends were prepared by solution casting. These polymers were found to be miscible in the whole composition range as determined by DSC even though some crystallinity remains in blends with PVA concentrations above 50wt%. Dynamic mechanical measurements of these blends and PAA as a function of temperature show an increase in storage modulus, E', when they reach a temperature of 140°C that is well beyond their softening point. The E' increase in PAA beyond 140°C is attributed to an intramolecular reaction of cyclic anhydride formation that stiffens the chain. Isothermal storage modulus test as a function of time and FTIR measurements at 160°C of PAA and three blends show that this increase in E' is due to cyclic anhydride formation. Received: 4 November 1998/Revised version: 11 March 1999/Accepted: 11 March 1999     

Removal of Copper (II) Ions from Aqueous Solutions using Na‐mordenite

Abstract

The potential to remove copper (II) ions from aqueous solutions using Na‐mordenite, a common zeolite mineral, was thoroughly investigated. The effects of relevant parameters solution pH, adsorbent dose, ionic strength, and temperature on copper (II) adsorption capacity were examined. The sorption data followed the Langmuir, Freundlich, and Dubinin‐Radushkevich (D‐R) isotherms. The maximum sorption capacity was found to be 10.69 mg/g at pH 6, initial concentration of 40 mg/dm³, and temperature of 40°C. Different thermodynamic parameters viz., changes in standard free energy (ΔG⁰), enthalpy (ΔH⁰), and entropy (ΔS⁰) have also been evaluated and the results show that the sorption process was spontaneous and endothermic in nature. The dynamics of the sorption process were studied and the values of rate constant of adsorption, rate constant of intraparticle diffusion were calculated. The activation energy (E_a) was found to be 11.25 kJ/mol in the present study, indicating a chemical sorption process involving weak interactions between sorbent and sorbate. The interaction between copper (II) ions and Na‐mordenite is mainly attributable to ion exchange. The sorption capacity increased with the increase of solution pH and the decrease of ionic strength and adsorbent dose. The Na‐mordenite can be used to separate copper (II) ions from aqueous solutions.     

Drug releasing characteristics of thermo- and pH-sensitive interpenetrating polymer networks based on poly (N-isopropylacrylamide)

Interpenetrating polymer networks (IPNs) of poly(N-isopropylacrylamide)/polyurethane (PNIPAAm/PU) and poly(N-isopropylacrylamide)/poly(acrylic acid) (PNIPAAm/PAA) were synthesized to investigate the swelling and drug releasing behavior. The presence of urethane network in PNIPAAm/PU IPNs improved the mechanical strength, but reduced the swelling and drug releasing rates because of its hydrophobic characteristics. The swelling transition temperatures of PNIPAAm gels were little affected by the incorporation of PU networks in IPN structures. The drug releasing process was analyzed with a simple exponential expression of time dependent fractional drug release. The swelling and drug releasing behavior of PNIPAAm/PAa IPNs was significantly affected by the variation of PAA compositions. The drug release process changed from anomalous to dual type via zero-order mode with increasing PAA concentration due to the competitive swelling rates between PNIPAAm and PAA during release process. The releasing rate decreased in the buffer solution of pH 7.4, but increased in that of pH 5.0 with increasing PAA concentration at both 28 and 37°C because the swelling power of PAA in pH 5.0 was much less than that in pH 7.4. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2647–2655, 1997     

A new approach to prepare highly loaded aqueous alumina suspensions with temperature sensitive rheological properties

Poly(acrylic acid) (PAA)-free alumina suspensions with temperature sensitive rheological properties have been successfully produced using the combination of tri-ammonium citrate and magnesium citrate powders with slurry loading up to 60 vol.%. A new approach using the DLVO concept is proposed to design the suspension composition. Both the shear viscosity and the shear modulus of the suspensions start to increase when the suspension temperature is above a critical value. The flocculation of the suspensions is controlled by the dissolution of the magnesium citrate that increases the ionic strength in the suspensions. The dissolution is controlled by the pH of the suspensions, which decreases with increasing temperature. Compared with the same solid loading suspensions containing PAA, the suspension shear viscosity of 25 °C can be reduced, which is useful in developing new near net shape forming technologies.     

Synthesis of novel acrylic modified water reducible alkyd resin: Investigation of acrylic copolymer ratio effect on film properties and thermal behaviors

New four‐component water reducible acrylic modified alkyd resins that are based on 1,3‐propanediol and contain different ratios of acrylic copolymer (AC) were synthesized by using a novel four‐stage fatty acid method. The final content of solids in the water reducible acrylic modified alkyd resins was 60% by weight. After the modified alkyd resin films were cured at 150°C for 1 h, it was observed that the use of AC as the modifier component had improved their physical and chemical surface coating properties and thermal behaviors. Experimental results show that the optimum AC ratio is 40% of the equivalent amount of AC to alkyd resin. Low‐volatile organic compounds (VOC) content water reducible acrylic modified alkyd resins yielded soft and flexible films with high chemical/thermal resistance, suitable for manufacturing of surface coating binders. POLYM. ENG. SCI., 56:947–954, 2016. © 2016 Society of Plastics Engineers     

Synthesis of four-component acrylic-modified water-reducible alkyd resin: investigation of dilution ratio effect on film properties and thermal behaviors

This study investigated the effect of the dilution ratio on film properties of acrylic-modified water-reducible alkyd resins. First, new four-component acrylic-modified alkyd resins based on 1,3-propanediol containing 40% of the equivalent amount of acrylic copolymer to alkyd resin were synthesized using the fatty acid method. The synthesized acrylic-modified alkyd resin was then dissolved in isopropyl alcohol (IPA) at various ratios and further diluted using distilled water at various ratios to obtain by-weight percentages of 70/50, 70/60, and 80/60 of solid content to IPA and water, respectively. Films of the modified alkyd resins were prepared, and cured at 150°C for 1 h, then their physical and chemical surface coating properties and thermal behaviors were investigated. The best results were obtained for the by-weight percentages of 80/60.     

Ionic liquid modified lignin-phenol-glyoxal resin: a green alternative resin for production of particleboards

The aim of this research was to evaluate the properties of particleboard panels bonded with ionic liquid treated lignin- phenol- glyoxal (LPG) resin. For this purpose, soda bagasse lignin was modified by 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) ionic liquid and then various contents of virgin and modified lignin (20, 30 and 40 wt% based on weight of phenol), phenol and glyoxal were used for synthesis of LPG resins. After resin synthesis, thermal and physicochemical properties of the synthesized resins such as curing behavior, gelation time, viscosity, solid content and density were measured. Finally, the resins so prepared were used for laboratory particleboard manufacturing. The panels physical (water absorption, thickness swelling) as well as mechanical (MOE, MOR and internal bond strength) properties were measured according to standard methods. The resins tests indicated that modification of lignin with ionic liquid not only can accelerate the gelation time and increase viscosity, density and solid content of LPG resins but also decrease the temperature required for curing the LPG resins. Based on the results of this work, the mechanical strength and dimensional stability of the particleboards bonded with a LPG resin can be improved by using modified lignin. The particleboards prepared with the LPG resin, using either modified or virgin lignin, presented higher water absorption as well as weaker mechanical strength than those prepared with the control PF resin. However, there does not appear to be any statistically significant difference between the some properties of the panels bonded with the control PF resin and those bonded with the LPG resin containing modified lignin.     

Thermal and mechanical properties of bio-based polymer networks by thiol-ene photopolymerizations of gallic acid and pyrogallol derivatives

Allylated pyrogallol (A3PG) and acrylated pyrogallol (Ac3PG) as bio-based trienes, and allylated gallic acid (A4GA) and acrylated allyl gallate (Ac3A1GA) as bio-based tetraenes were synthesized from pyrogallol and gallic acid, respectively. Thiol-ene photopolymerizations of the bio-based polyenes and a pentaerythritol-based primary tetrathiol (pS4P) at the allyl/SH ratio of 1/1 produced photo-cured resins (A3PG-pS4P, Ac3PG-pS4P, A4GA-pS4P and Ac3A1GA-pS4P). The FT-IR spectral analysis revealed that thiol-ene reactions of thiol/allyl and thiol/acryloyl groups smoothly proceeded. Gel fractions of acryl-based cured resins were a little higher than those of allyl-based cured resins. The swelling test and dynamic mechanical analysis revealed that GA- and acryl-based cured resins exhibited higher crosslinking densities than PG- and allyl-based cured resins, respectively. A higher order of tan δ peak temperature was Ac3PG-pS4P (48.3 ° C) > Ac3A1GA-pS4P (24.1 ° C) > A4GA-pS4P (22.1 ° C) > A3PG-pS4P (?7.8 ° C). Ac3PG-pS4P displayed the highest 5 % weight loss temperature, tensile strength and tensile modulus among all of the cured resins.     

Fluorocarbon‐containing hydrophobically modified poly(acrylic acid) gels as drug release system

Hydrophobically modified acrylic acid (AA) hydrogels containing fluorocarbon hydrophobic group and hydrocarbon‐modified gels using 2‐(N‐ethylperfluorooctanesulfoamido) ethyl methacrylate (FMA), and lauryl acrylate (LA) respectively, 2‐(N‐ethylperfluorooctanesulfoamido) ethyl methacrylate (FMA), were synthesized. Acetaminophen, with analgesic and antipyretic property, acted as the model drug. Swelling, rheological, and mechanical properties of the gels were investigated. Fluorocarbon‐modified gels show the stronger hydrophobicity than do the hydrocarbon‐modified gels, which affected the gel's drug‐releasing behavior. The drug release behavior depends on pH of the solution medium, the type of hydrophobic modification and the amount of hydrophobes. Hydrophobically modified PAA gels have higher storage modulus E′ than the unmodified PAA gels. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Bismaleimide Systems for High-Performance Radomes

Three modified bismaleimide resin systems (designated as systems I, II, and III) for high-performance radomes are introduced. Their glass transition temperatures are 274°, 268°, and 265°C, respectively; and their dielectric loss tangents at 10 GHz are 0.0117, 0.0108, and 0.0118, respectively. System I and system II are suitable for hot-pressing process; and system III, which has attractive processing characteristics, is suitable for resin transfer molding (RTM). The injection temperature of system III is room temperature, at which its viscosity is only 0.38 Pa·sec. In addition, its working life is more than 40 h. Properties of neat resins and composites are investigated; all data show that they have good thermal and mechanical properties as well as excellent dielectric properties. These indicate that the three modified bismaleimide resins can be used as matrix resins for advanced radomes.     

Bioartificial materials based on blends of collagen and poly(acrylic acid)

The interactions between soluble collagen (C) from calf skin and poly(acrylic acid) (PAA) were studied. Mixing aqueous solutions of collagen and PAA, at various pH values (2.5–4), leads to the formation of complexes that precipitate in the form of insoluble aggregates. The effects of mixture composition, pH, and ionic strength on C/PAA complex formation were investigated by gravimetric, turbidimetric, and conductometric analysis. The experimental results indicate that the complexes form through electrostatic interactions. Homogeneous solid films with variable C/PAA ratios were obtained by casting from solutions in which the pH was adjusted just over the isoelectric point of collagen, thus avoiding the attractive ionic interactions responsible for the complexation of collagen and PAA molecules. A relevant result obtained is related to the possibility of restoring the ionic interactions between the two polymers inside the solid films. Mixture composition and pH appear to influence the thermal properties of both complexes and films. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 971–976, 1999     

Effective Acid Printing of Protein and Nylon-6 Fabrics Using New Thickening Agents

Printing of wool, silk, and nylon-6 substrates with acid dyes using new thickening agents based on free radical polymerization of acrylic acid (AA) with tamarind seed gum (TG) or karaya gum (KG) was investigated. The depth of the obtained prints follows the decreasing order: PAA/TG2 > PAA/TG1 > PAA/KG1 > PAA/KG2 > GG. Increasing the new thickener concentration up to 75 g and steam fixation at 105°C for 30 minutes gives higher K/S values. Printability substrates follows the descending order: wool > nylon-6 > silk.     

Epoxy-Imide Resins from N-(4- and 3-Carboxyphenyl) Trimellitimides: Modified with Reactive Rubbers

ABSTRACT

Epoxy-imide resins obtained through the reaction of epoxy resins such as Araldite® GY 250/Araldite® EPN 1138 with N-(4- and 3-carboxyphenyl)trimellitimides (IDA-I and IDA-II, respectively) have been modified with 10 wt% of epoxidized hydroxyl-terminated polybutadiene (EHTPB), 10 phr of carboxyl-terminated butadiene-acrylonitrile liquid copolymer (CTBN-L), and 10 phr of carboxyl-terminated butadiene-acrylonitrile solid copolymer (CTBN-S) without sacrificing much of their performance at elevated temperatures. Adhesive lap shear strength on stainless steel substrate at room temperature and at 100, 125, and 150°C has been evaluated for the modified and unmodified systems. CTBN-S offers a remarkable increase of 13 MPa and 8 MPa in the room temperature adhesive strength of GY 250-based system and EPN 1138-based system, respectively. EHTPB gives only a marginal improvement and CTBN-L offers an improvement by 4 MPa for GY 250-based system whereas CTBN-L reduces the adhesive strength of EPN 1138-based system. SEM studies suggest that in general, the modification with EHTPB and CTBN-L results only in improving the ductility of epoxy-imide systems, whereas the modification with CTBN-S results in phase separation of rubber particles in the epoxy-imide matrix.     

Influence of Resin Molecular Weight on Curing and Thermal Degradation of Plywood Made From Phenolic Prepreg Palm Veneers

The present work evaluates curing and the thermal behavior of different molecular weight phenol formaldehyde (PF) resins used to prepare PF prepreg oil palm stem veneers. The physical properties (solid contents, gelation time, pH, and viscosity) of PF resins were determined. The molecular weight of resins was characterized by gel permeation chromatography, whilst thermal properties were determined by differential scanning calorimetry and thermogravimetric analyses. The average molecular weight of PF resins were 526 g/mole (low), 1889 g/mole (medium), and 5178 g/mole (control - commercial). Among the resins, medium (MMwPF) gives better thermal stability with a retained weight of 48.9% at 300°C. High (Commercial PF) had a low decomposition temperature (109.3°C) which occurred within 11 min. Both low (LMwPF) and MMwPF started to melt at ≥120°C. Based on strength and shear values, phenolic prepreg palm veneers can be prepared using either low or medium molecular weight PF but with varying results. In all cases, the mechanical properties of palm plywood made from PF prepreg veneers were superior to those made from PF-bonded plywood using the commercial process.