Acrylic Acid In Aqueous Solution Research Articles

Hydrogels Obtained via γ-Irradiation Based on Poly(Acrylic Acid) and Its Copolymers with 2-Hydroxyethyl Methacrylate

Hydrogels containing both carboxyl and hydroxyl functional groups have been prepared by γ-irradiation of either aqueous solutions of acrylic acid (AA) and mixtures of AA and 2-hydroxyethyl methacrylate (HEMA) in different ratios, or aqueous solutions of poly(AA), PAA, and poly(AA-co-HEMA) obtained via solution polymerization. A higher absorbed dose is required in order to prepare hydrogels from monomer solutions, compared with those from polymer solutions. The range for the absorbed doses was chosen so that the probability of crosslinking reactions is higher than that of degradation ones. As the radiation energy deposited in a sample increases, the equilibrium swelling degree and the average molar mass between crosslinks diminishes. Chemical transformations induced by radiation were investigated by means of FTIR spectroscopy and thermal analysis of polymers before and after irradiation. For all these systems, the formation of a three-dimensional network enhances the glass transition temperature and thermal stability, but a further increase in the crosslinking degree may have the reverse effect on the glass transition temperature. Depending on the preparation protocol and/or hydrogel composition, superabsorbent materials that can bind different compounds throughout side functional groups may be obtained.

Solution Polymerization of Acrylic Acid Initiated by Redox Couple Na-PS/Na-MBS: Kinetic Model and Transition to Continuous Process

This work aims at modeling in detail the polymerization of non-ionized acrylic acid in aqueous solution. The population balances required to evaluate the main average properties of molecular weight were solved by the method of moments. The polymerization process considered is initiated by a persulfate/metabisulfate redox couple and, in particular, the kinetic scheme considers the possible formation of mid-chain radicals and transfer reactions. The proposed model is validated using experimental data collected in a laboratory-scale discontinuous reactor. The developed kinetic model is then used to intensify the discontinuous process by shifting it to a continuous one based on a tubular reactor with intermediate feeds. One of the experimental runs is selected to show how the proposed model can be used to assess the transition from batch to continuous process and allow faster scale-up to industrial scale using a literature approach.

Study on The Concentration of Acrylic Acid and Acetic Acid by Reverse Osmosis.

In the production of acrylic acid, the concentration of acrylic acid solution from the adsorption tower was low, which would lead to significant energy consumption in the distillation process to purify acrylic acid, along with the production of a large amount of wastewater. Reverse osmosis (RO) was proposed to concentrate the acrylic acid aqueous solution taken from a specific tray in the absorption tower. The effects of operating conditions on the permeate flux and acid retention were studied with two commercial RO membranes (SWC5 and SWC6). When the operating pressure was 4 MPa and the temperature was 25 °C, the permeate fluxes of two membranes were about 20 L·m−2·h−1. The acrylic acid and acetic acid retentions were about 80% and 78%, respectively. After being immersed in the acid solutions for several months, the characteristics of the two membranes were tested to evaluate their acid resistance. After six months of exposure to the acid solution containing 2.5% acrylic acid and 2.5% acetic acid, the retentions of acrylic acid and acetic acid were decreased by 5.7% and 4.1% for SWC5 and 4.9% and 2.2% for SWC6, respectively. The changes of membrane surface morphology and chemical composition showed the hydrolysis of some amide bonds.

Development of a superabsorbent polymer using iodine transfer polymerization

We succeeded in developing a novel class of acrylic acid (AA)-based superabsorbent polymers (SAPs) with remarkably improved absorption performance by applying iodine transfer polymerization (ITP). A specific organoiodine chain transfer agent was newly developed and found to provide moderate to good control over the polymerization of AA in aqueous solution. Dynamic light scattering (DLS) measurements revealed that the polymer network prepared using our ITP technology is relatively homogeneous. Our new SAP exhibits a good balance between absorption capacity and gel strength, and it enables a quick response to diversified customer needs in the diaper industry. To the best of our knowledge, this work is the first case in which reversible-deactivation radical polymerization (RDRP) has been practically applied to commodity polymer products. This review focuses on how we connected the old but highly practical ITP and SAP production. This review summarizes the successful development and commercialization of a superabsorbent polymer (SAP) using iodine transfer polymerization (ITP). We found that the overall absorption performance of the SAP was improved by applying ITP and that this improvement was related to the homogenization of the polymer network. This innovation enables the quick response to diversified customer needs in the diaper industry. We believe that this achievement will contribute to improving the quality of life of people around the world.

Coating of urea granules by in situ polymerization in fluidized bed reactors

Abstract The main objective of the present work is to produce and characterize urea granules coated with polymers prepared with aqueous solutions of acrylic acid and glycerol. Both coating and drying of urea granules were performed in a fluidized bed reactor. Fourier transform infrared spectroscopy analyses indicated the presence of poly(acrylic acid) and acrylic acid / glycerol copolymers on the granule coating and the formation of chemical bonds between urea and the polymer coating. Scanning electron microscopy images showed that the original and coated urea granules presented different characteristics, reinforcing the idea that coating occurs in the fluidized bed. Finally, rates of urea release showed that the coated granules presented slightly slower rates of urea dissolution in water due to the presence of the coating layer. Therefore, it is shown that it is possible to produce coated urea granules through in-situ polymerization onto the granule surface using a fluidized bed.

Single-step process to improve the mechanical properties of carbon nanotube yarn.

Carbon nanotube (CNT) yarns exhibit low tensile strength compared to conventional high-performance carbon fibers due to the facile sliding of CNTs past one another. Electron beam (e-beam) irradiation was employed for in a single-step surface modification of CNTs to improve the mechanical properties of this material. To this end, CNT yarns were simultaneously functionalized and crosslinked using acrylic acid (AA) and acrylonitrile (AN) in an e-beam irradiation process. The chemical modification of CNT yarns was confirmed by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and scanning electron microscopy (SEM). The best improvement in mechanical properties was achieved on a sample treated with an aqueous solution of AA and subsequent irradiation. CNT yarn treatment with AA enhanced the strength (444.5 ± 68.4 MPa) by more than 75% and the modulus (21.5 ± 0.6 GPa) by more than 144% as compared to untreated CNT yarn (strength 251 ± 26.5 MPa and modulus 8.8 ± 1.2 GPa).

Shrinkage and swelling behavior of archaeological waterlogged wood preserved with slightly crosslinked sodium polyacrylate

In this article, the conservation of archaeological waterlogged wood (WW) of Afzelia sp. (medium degraded: Umax = 385%) was impregnated in vacuum with an aqueous solution of acrylic acid (AA), sodium acrylate monomer (AANa), crosslinking agent (MBA) and catalyst (V-501). The simultaneous in situ polymerization and crosslinking resulted in slightly crosslinked sodium polyacrylate (PAANa) in the wood structure. The results showed that untreated WW had only a very limited ability to re-swell to recover its original dimensions from a collapsed condition, while WW protected by crosslinked PAANa could almost fully recover its original shape and size even after several drying–rewetting cycles. From microscopic observations, treated wood was found to maintain its original cell structure, form and shape even after repeated drying–rewetting cycles. PAANa was observed to be densely localized near the middle lamella, the cell corners, and the cell lumina by transmission electron microscopy observation. These observations suggest that our PAANa treatment provides reasonable strength as well as favorable hydrophilicity to avoid hornification of the cell wall upon drying, thus providing unique shape recovery properties.

Radiation-induced graft polymerization of acrylic acid and glycidyl methacrylate onto abaca/polyester nonwoven fabric

ABSTRACTSurface modified fibrous materials that possess carboxylic and amine functional groups were developed from a nonwoven fabric (NWF) containing abaca fibers. A facile method was employed for graft polymerization of acrylic acid (AA) and glycidyl methacrylate (GMA) from an electron beam irradiated abaca/polyester NWF. Materials with sufficient amount of graft chains were prepared after reaction of NWF, irradiated at a maximum absorbed dose of 40 kGy, with 15% AA aqueous solution and 5% GMA emulsion for 2 and 3 hours, respectively. Characterization of the pristine, grafted, and functionalized materials with FTIR, TGA, and SEM indicates that grafting and functionalization were successfully performed. The batch adsorption studies showed that the PAA-modified NWF exhibited higher affinity toward Ni2+, Cd2+, and Pb2+ than the EDA-modified abaca/polyester-g-PGMA.

Incorporated Poly Acrylic Acid-co-Fe3O4 Nanoparticles Mixed Matrix Polyethersulfone based Nanofiltration Membrane in Desalination Process

Polyethersulfone (PES) based nanocomposite nanofiltration membrane was prepared by immersion precipitation method and casting solution technique using poly (acrylic acid) grafted-iron oxide nanoparticles (Fe3O4) as hydrophilic filler additives. For this purpose, iron oxide nanoparticles were modified by in situ polymerization of acrylic acid in aqueous solution by potassium persulfate as initiator and ethylene glycol as cross-linker. The grafted iron oxide nanoparticles were investigated by Fourier transforms infrared spectroscopy. The effect of different concentrations of grafted nanoparticles on the PES nanofiltration membrane performance and properties was investigated by scanning electron microscopy, water content, pure water flux, pore size, permeability flux, rejection and tensile strength. The water content was enhanced by incorporation of nanoparticles into the membrane matrix from 72.04 to 74.75%. It was observed that pure water flux (2.68 to 8.71 L/m2.h), mean pore size (2 to 6 nm) and permeability flux (0.8 to 4 L/m2.h) improved with loading of nanoparticles into the membrane matrix. The results revealed that utilization of grafted iron oxide nanoparticles in the membrane matrix led to improvement of rejection from 53.98 to 89.19% for membrane filled with 0.05% wt. nanoparticles. Also tensile strength increased slightly for sample 1 from 3874 to 4825 kPa for sample 4. Moreover, results showed more appreciation performance for the modified membrane containing PAA-Fe3O4 composite nanofillers compared to membrane filled with bare Fe3O4 nanoparticles.

Hydrogels Synthesized by Electron Beam Irradiation for Heavy Metal Adsorption.

Poly(acrylamide co-acrylic acid) hydrogels were prepared by free-radical copolymerization of acrylamide and acrylic acid in aqueous solutions using electron beam irradiation in the dose range of 2.5 kGy to 6 kGy in atmospheric conditions and at room temperature. The influence of the absorbed dose, the amount of cross-linker (trimethylolpropane trimethacrylate) and initiator (potassium persulfate) on the swelling properties and the diffusion coefficient and network parameters of hydrogels were investigated. The structure and morphology of hydrogels were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The use of the obtained hydrogels by the removal of Cu2+ and Cr6+ from aqueous solutions was investigated at room temperature. During the adsorption of metal ions on hydrogels, the residual metal ion concentration in the solution was measured by an atomic absorption spectrophotometer (AAS). It has been established that the use of a relatively small amount of trimethylolpropane trimethacrylate for hydrogel preparation has led to the increasing of swelling up to 8500%.

Importance of Dimer Quantification for Accurate Catalytic Evaluation of Lactic Acid Dehydration to Acrylic Acid

Catalytic dehydration of lactic acid in the presence of water is a potentially green, synthetic approach for the production of acrylic acid, and development of a highly selective catalyst is a primary challenge, leading to a resurgence in catalyst exploration and discovery. However, because the complexity in the analytical assessment of the efficiency of catalysts stemming from the possible presence of dimers in lactic acid feedstocks has often been neglected in the literature, we demonstrate, without consideration of the dimer during catalyst evaluation, that they can have a substantial influence on the determination of conversion of lactic acid and selectivity to acrylic acid in aqueous solution. In one example of a modified zeolite catalyst, a true acrylic acid of selectivity of 64% was overestimated to be 80% if the dimers in the feed solution were neglected in the analytical analysis. A survey of the literature demonstrated very few researchers account for the possible presence of lactic acid dimers ...

Continuous flow synthesis of poly(acrylic acid) via free radical polymerisation

The free radical polymerisation of aqueous solutions of acrylic acid (1) has been studied using a continuous flow reactor to quickly screen reaction parameters such as temperature, residence time, monomer- and initiator concentration.

Continuous Pilot-Scale Tubular Reactor for Acrylic Acid Polymerization in Solution Designed Using Lab-Scale Rheo-Raman data

A continuous pilot-scale tubular reactor is designed for the polymerization of acrylic acid in aqueous solution. The reactor is equipped with CSE-X static mixers from Fluitec which strongly increase heat and mass transfer despite laminar flow. A mathematical model of the reactor is proposed assuming that it is a perfect plug-flow reactor and using kinetic and rheological equations previously established using a lab-scale rheo-Raman device. Calculated values of temperature and polymer concentration profile along the reactor as well as outlet average molar masses and viscosity are in good agreement with experimental results. Provided that the outlet viscosity of reaction medium does not exceed 0.5 Pa s, no reactor fouling occurred. On the contrary, fouling is detected after 6 to 8 h running with higher viscosities. This work is the first demonstration of applicability of CSE-X static mixer elements in a continuous polymerization process producing high molar mass water-soluble polymer. In addition, successful scale-up of polymerization reactor is reported up to pilot-scale as well as batch to continuous transposition, only on the basis of lab-scale rheo-Raman data. The interest of rheo-Raman device for the acquisition of primary data is established.

Synthesis and Characterization of Graft Copolymers of Acrylic Acid onto Starch

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.

Continuous Pilot‐Scale Tubular Reactor for Acrylic Acid Polymerization in Solution Designed Using Lab‐Scale Rheo‐Raman data

A continuous pilot‐scale tubular reactor is designed for the polymerization of acrylic acid in aqueous solution. The reactor is equipped with CSE‐X static mixers from Fluitec which strongly increase heat and mass transfer despite laminar flow. A mathematical model of the reactor is proposed assuming that it is a perfect plug‐flow reactor and using kinetic and rheological equations previously established using a lab‐scale rheo‐Raman device. Calculated values of temperature and polymer concentration profile along the reactor as well as outlet average molar masses and viscosity are in good agreement with experimental results. Provided that the outlet viscosity of reaction medium does not exceed 0.5 Pa s, no reactor fouling occurred. On the contrary, fouling is detected after 6 to 8 h running with higher viscosities. This work is the first demonstration of applicability of CSE‐X static mixer elements in a continuous polymerization process producing high molar mass water‐soluble polymer. In addition, successful scale‐up of polymerization reactor is reported up to pilot‐scale as well as batch to continuous transposition, only on the basis of lab‐scale rheo‐Raman data. The interest of rheo‐Raman device for the acquisition of primary data is established. image

Application of Raman Spectroscopy to Characterization of Residence Time Distribution and Online Monitoring of a Pilot‐Scale Tubular Reactor for Acrylic Acid Solution Polymerization

A pilot‐scale tubular reactor containing static mixers is equipped with several Raman probes in order to perform online monitoring of radical copolymerization of acrylic acid in aqueous solution. This setup allows determination of residence time distribution while polymerization reaction occurs, using sodium nitrate as a tracer. These results prove that the use of convenient static mixers allows obtaining a nearly perfect plug‐flow reactor in all explored conditions (reactive and nonreactive medium, between 0.001 and 1 Pa s viscosity). Furthermore, the dynamics of the pilot‐scale reactor is characterized. Experimental transient and steady‐state values are compared to predictions based both on residence time distribution and model of polymerization kinetics. The applicability of Raman spectroscopy to online monitoring of pilot‐scale reactors is demonstrated. image

Electron Beam Synthesis and Characterization of Acrylamide/Acrylic Acid Hydrogels Using Trimethylolpropane Trimethacrylate as Cross-Linker

The purpose of the paper is to present the synthesis and characterization of hydrogels prepared by free-radical copolymerization of acrylamide and acrylic acid in aqueous solutions using potassium persulfate as initiator and trimethylolpropane trimethacrylate as cross-linker, via the radiation technique. The samples were subjected to electron beam treatment in the dose range of 2 to 4 kGy and the influence of the absorbed dose and amount of cross-linker on the swelling properties, diffusion coefficient, and network parameters of hydrogels was investigated. A possible reaction mechanism for acrylamide/acrylic acid/trimethylolpropane trimethacrylate hydrogels was also suggested. The structure and morphology of hydrogels were characterized by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy.

Synthesis and Characterization of Poly(Acrylamide-Co-Acrylic Acid) Flocculant Obtained by Electron Beam Irradiation

The goal of the paper was to prepare a class of flocculants by free-radical copolymerization of acrylamide with acrylic acid in aqueous solutions in the presence/absence of potassium persulphate as initiator. Reaction medium was submitted to electron beam treatment of 0.6 to 1.5 kGy in atmospheric conditions and at room temperature. Because of the complexity of reaction mechanisms involved in radio-induced polymerization, was necessary to establish the connection between absorbed dose and initiator concentration, both of them very important in free radical production. Unlike the conversion coefficient and residual monomer concentration, intrinsic viscosity and Huggin’s constant are sensitive to the initiator concentration variation for all used irradiation doses. The copolymerization was confirmed by FTIR measurements. The flocculation characteristics were evaluated in 0.2 wt % kaolin suspension at room temperature using different polymer dosages between 0 to 10 ppm. High flocculation efficiency was obtained using the polymer having high values of intrinsic viscosity, molecular weight and radius of gyration.

A simple TLC-densitometric method for the quantification of acrylic acid in aqueous solutions

Because acrylic acid is a volatile organic compound, the precise quantification of acrylic acid by thin-layer chromatography (TLC) analysis is difficult. Herein, we report a simple TLC–densitometric method for the quantification of acrylic acid in aqueous solutions following a labeling procedure using the Mizoroki-Heck coupling reaction. To make acrylic acid nonvolatile and highly sensitive for ultraviolet (UV) detection, acrylic acid in an aqueous solution was reacted with iodobenzene in a dimethyl sulfoxide solution using a base (potassium carbonate) and a catalyst (FibreCat 1001), affording trans-cinnamic acid. High-performance liquid chromatography (HPLC) analysis showed that acrylic acid could be labeled over a range of 0.01–10 mM at 60°C for 30 min and the average reaction yield was 96.0%. To quantify acrylic acid by TLC analysis, the reaction mixture was extracted using ethyl acetate and then spotted on a silica gel 60 F254 TLC plate. The spots corresponding to the labeled acrylic acid over a range...

A new approach of synthesis and morphological control of poly(ethylene terephthalate)-g-polyacrylonitrile composite film with a porous surface

Poly(ethylene terephthalate)-g-polyacrylonitrile (PET-g-PAN) composite film with a porous surface was fabricated via gamma-ray-radiation-induced graft polymerization on PET film in an aqueous solution system. The original PET film was first irradiated by gamma ray in the aqueous solution of acrylic acid. Next, the graft polymerization of acrylonitrile (AN) was induced by gamma ray on the surface of the above modified PET film in an aqueous solution of AN. The prepared PET-g-PAN composite film has a smaller static water contact angle than the original PET film. The SEM and AFM images show that the grafted PAN layer on the surface of PET-g-PAN composite film is composed of closely-arranged spherical PAN microspheres with an average diameter of 30nm. The gaps between the PAN microspheres form fine pores (less than 30nm) on the surface. The gas barrier property of the PET-g-PAN composite film is much better than that of the original PET film. This work provides a facile and green method to prepare PET-g-PAN composite film with a controllable porous surface morphology by taking advantage of the radiation-induced graft polymerization technique in an aqueous solution system.