Percentage Swelling Research Articles

Gamma‐radiation initiated synthesis of Psyllium and acrylic acid‐based polymeric networks for selective absorption of water from different oil–water emulsions

AbstractRemoval of water from the crude petroleum during its extraction and refining process is one of the major problems faced by petroleum industries, so in this study a superabsorbent has been synthesized from Psyllium and acrylic acid based polymers under the influence of gamma radiations using hexamine as a crosslinker. After optimizing various reaction parameters, the optimized superabsorbent has been tested for its selective water absorption capacity from different oil–water emulsions as a function of time, temperature, pH, and NaCl concentration. The synthesized superabsorbent has been found to be highly selective toward water absorption with maximum percent swelling of 8560% in petrol–water emulsion. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

A Comparative Analysis of Wave Formation and Preservation by Treatment with Sodium Bromate and Hydrogen Peroxide as Oxidant of Permanent Wave

The permanent wave is useful method for soft and natural wave formation, and thereby the long time wave preservation and weak hair damage are needed. So that, wave formation and preservation, physicochemical properties and morphological change of virgin hair shaft were investigated for the optimal condition of permanent wave by before and after treatment with thioglycolic acid and two kinds of oxidants. In the result, soft and elastic S-curls were formed by one time treatment with hydrogen peroxide in 10 minutes and sodium bromate in 20 minutes, and wave preservation in sodium bromate group were better in compared with hydrogen peroxide group. In contrast to the low percentage of water swelling and alkali solubility as physicochemical properties, value of thickness and tensile strength of hair shafts were higher in sodium bromate treated group. And weak change of cuticles such as nick and stripped were observed in both of oxidants treated group. In conclusion, one time treatment of sodium bromate and hydrogen peroxide may be better than two times treatment. Hydrogen peroxide treatment may be useful for good wave formation, and long time wave preservation can be used by treatment of sodium bromate.

Cu(II) immobilization in AAc/NIPAAm-based polymer systems synthesized using ionizing radiation

Polymer systems based on the pH-responsive monomer acrylic acid (AAc) and the thermosensitive monomer N-isopropylacrylamide (NIPAAm) were synthesized using gamma radiation. Three systems were synthesized: a comb-type hydrogel structure (grafting of NIPAAm onto crosslinked PAAc), a binary graft of both monomers onto a polypropylene (PP) film synthesized by a one-step method and a binary graft prepared by a two-step method. The binary graft systems were characterized by swelling behavior and the reversibility of water uptake. The three systems were compared with respect to their Cu(II) adsorption quantity, reversibility and time response. The binary graft system synthesized in one step exhibited the best adsorption response. The comb-type hydrogel required 150 h to reach its maximum swelling percentage, and the binary graft systems on polypropylene (PP) prepared by the one- and two-step irradiation-based methods required 10 and 30 min, respectively. The optimum pH range for Cu(II) immobilization was 5–6 in the binary graft system synthesized in one step. The maximum adsorption capacity for Cu(II) in the (PP-g-(AAc/NIPAAm)) (45% graft) was found to be 337 mg g −1, and the adsorption followed the Freundlich model.

The Prediction of Swell Percent and Swell Pressure by Using Neural Networks

Expansive soils exhibit significantly high volumetric deformations and so pose a serious threat to stability of the structures and foundations. Thus, determination of their swelling properties (i.e. swelling potential and swell pressure) becomes essential. However, measurement of the swelling properties is time-consuming and requires special and expensive equipment. With this in view, efforts were made to develop artificial neural network (ANN) and multiple regression analysis (MRA) models that can be employed for estimating swell percent and swell pressure. To achieve this, the results of free swell tests performed on statically compacted specimens of Kaolinite-Bentonite clay mixtures with varying soil properties were used. Two different ANN (ANN-1 and ANN-2) and MRA (MRA-1 and MRA-2) models have been developed: ANN-1 and MRA-1 models for predicting swell percent and ANN-2 and MRA-2 models for predicting swell pressure. The results obtained from ANN and MRA models were compared vis-à-vis those obtained from the experiments. The values predicted from the ANN models match the experimental values much better than those obtained from MRA models. Moreover, several performance indices such as determination coefficient (R2), variance account for (VAF), mean absolute error (MAE), and root mean square error (RMSE) were calculated to check the prediction capacity of the ANN and MRA models developed. The obtained indices make it clear that the constructed ANN models have shown higher prediction performance than MRA models. It has been demonstrated that the ANN models can be used satisfactorily to predict swell percent and swell pressure as a rapid inexpensive substitute for laboratory techniques.

Rapid Synthesis of Acrylamide onto Xanthan Gum Based Hydrogels under Microwave Radiations for Enhanced Thermal and Chemical Modifications

The main objective of this research work is to synthesize crosslinked hydrogel from xanthan gum and acrylamide under the influence of microwave radiations by graft polymerization technique in presence of potassium persulphate-N,N'-methylene-bis-acrylamide as initiator-crosslinker system. Different reaction parameters such as reaction time, pH, solvent and initiator concentration were optimized a function of percentage grafting. Monomer and cross-linker concentrations were optimized as a function of percentage swelling for getting the polymer with maximum water absorption capacity. The superabsorbent was characterized using different characterization techniques like, FTIR, TGA / DTA / TDG and X-ray diffraction. The candidate polymer was found to be thermally more stable than the xanthan gum.

Mechanical properties of rice straw fiber-reinforced polymer composites

Rice straw fibers have been used as reinforcing fillers in different polymers, tow composites were prepared by using polyvinyl alcohol and polystyrene polymers with different ratio of polymers. The pressed samples were subjected to various electron beam irradiation dose. The results indicated that, flexural strength, impact strength and modulus of elasticity increase with increasing the polymer ratio in the mix composition. It was found that the water absorption and thickness swelling percentages of rice straw fiber polystyrene composites decrease with increasing the polystyrene content in the same composition, while its values for rice straw polyvinyl alcohol composites improve. These are attributed to hydrophobic and hydrophilic characteristics of the tow composites. The improvement of physico-mechanical properties of both composites with the increase of electron beam irradiation dose are probably attributed to randomly initiated chain reactions, which started by the reactive centers created by electron beam. These observations were confirmed by IR spectrometer and SEM studies.

Study on Polyvinly-Alcohol(PVA)/ Iron Oxide Black(<i>Fe<sub>3</sub>O<sub>4</sub></i>) and Polyvinly-Alcohol(PVA)/ Iron Oxide Red(<i>Fe<sub>2</sub>O<sub>3</sub></i>) Magnetic Sensitive Hydrogel

Iron oxide black and iron oxide red magnetic sensitive to polyvinly-alcohol hydrogel has been fabricated using physical cross-linking method. The mechanical properties and swelling characteristics have been studied for different content, magnetic sensibility were tested using the vibration sample magnetometer, experiment results show that iron oxide red hydrogel has better mechanical properties, Percentage of swelling and loss rate of water of the polyvinly-alcohol hydrogel decrease with the increasing of the magnetic particles content, the change tendency is very like, cross-linking is increased with performance the swelling performance decreasing; PVA and Fe3O4 has good response from the SEM photo and IR spectrogram; its magnetic properties is better.

Constancy of the Orbscan acoustic factor to detect contact lens‐induced corneal swelling

Purpose: The aim of the present study was to compare central and peripheral corneal thickness measurements in corneas with and without contact lens (CL)‐induced corneal swelling, in order to establish the constancy of the Orbscan acoustic factor (AF) for reliability in detection of CL‐induced corneal swelling.Methods: Corneal thickness was measured in five corneal locations (central, superior, inferior, nasal and temporal) using both ultrasonic and Orbscan pachymetry before and after one week of high Dk (lotrafilcon A) and low Dk (etafilcon A) contact lens continuous wear (CW). Lenses were randomly fitted for CW in the right and left eyes of 20 healthy subjects to induce various amounts of corneal swelling.Results: Etafilcon A contact lenses induced greater corneal swelling than the lotrafilcon A contact lenses (p < 0.05, paired Student t‐test). Equal corneal swelling percentages (with and without the application of the acoustic factor) were determined from Orbscan measurements. Application of the 0.92 AF did not permit adjustment to all corneal locations. The correlations between Orbscan with and without the 0.92 AF and ultrasonic pachymetry were higher for central pachymetry (r2 > 0.88; p < 0.01) and lower for peripheral pachymetry (r2 < 0.58; p < 0.01) with similar trends in corneas with and without CL‐induced swelling.Conclusions: The acoustic factor proposed by the manufacturer to obtain corneal thickness with the Orbscan compared with those from ultrasonic pachymetry was not valid for all corneal topographic positions. The AF is unnecessary when determining CL‐induced corneal swelling.

The Positive Effects of Nanoclay on the Hydraulic Conductivity of Compacted Kahrizak Clay Permeated With Landfill Leachate

AbstractThis study evaluates the effect of nanoclay on permeability, swelling, compressive strength, and cation exchange capacity of a compacted Kahrizak landfill clay liner. The results show that 4% nanoclay significantly reduces permeability (3 × 10−9 to 7.74 × 10−11 cm/s in neutral, 3.66 × 10−9 to 7.9 × 10−10 cm/s in acidic, and 3.25 × 10−9 to 5.24 × 10−10 cm/s in alkaline condition), and increases compressive strength (by 36.28%) and the percentage of swelling (from 16.67 to 41.82, 23.33 to 45.45, and 15 to 38.18 at pH 7, 4.8, and 9, respectively) compare to raw clay samples. Moreover, the results of cation exchange capacity tests show that adding 4% nanoclay to the Kahrizak clay, permeated with landfill leachate, helps the sample maintain its mono‐valent ions between layers and remains dispersed. The results of SEM and XRD analyses show that by adding nanoclay, nanoclay clusters are formed in the sample; as a result, the interlayer spacing decreases which makes it remain dispersed. XRF analyses also demonstrate that by adding nanoclay to the mixture, the permeability and therefore, the amount of heavy metals which can penetrate into it decreases. The results justify the construction of clay barriers with nanoclay in order to prevent leachate penetration, and consequently reduce the operation costs.

Modified polydimethylsiloxane/polystyrene blended IPN pervaporation membrane for ethanol/water separation

AbstractIn this article a modified polydimethylsiloxane (PDMS) blended polystyrene (PS) interpenetrating polymer network (IPN) membranes supported by Teflon (polytetrafluoroethylene) ultrafiltration membrane were prepared for the separation of ethanol in water by pervaporation application. The relationship between the surface characteristics of the surface‐modified PDMS membranes and their permselectivity for aqueous ethanol solutions by pervaporation are discussed. The IPN supported membranes were prepared by sequential IPN technique. The IPN supported membrane were tested for the separation performance on 10 wt % ethanol in water and were characterized by evaluating their mechanical properties, swelling behavior, density, and degree of crosslinking. The results indicated that separation performance, mechanical properties, density, and the percentage of swelling of IPN membranes were influenced by degree of crosslink density. Depending on the feed temperature, the supported membranes had separation factors between 2.03 and 6.00 and permeation rates between 81.66 and 144.03 g m−2 h−1. For the azeotropic water–ethanol mixture (10 wt % ethanol), the supported membrane had at 30°C a separation factor of 6.00 and a permeation rate of 85 g m−2 h−1. Compared to the PDMS supported membranes, the PDMS/PS IPN supported blend membrane ones had a higher selectivity but a somewhat lower permeability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Synthesis and characterization of poly(HEMA‐MAA) hydrogel carrier for oral delivery of insulin

AbstractPoly(HEMA‐MAA) hydrogel particles were synthesized by redox free‐radical polymerization using 2‐hydroxyethylmethacrylate, different concentration of methacrylic acid as monomer, ethyleneglycol dimethacrylate as crosslinking agent, and APS/TEMED as free‐radical initiator. Fourier transform infrared spectrum of poly(HEMA‐MAA) hydrogels showed intense absorption peak of carbonyl group at ∼ 1700 cm−1 due to carboxylic acid groups of MAA, peak at ∼ 2960 cm−1 due to CH stretching and vinylic peak at 1700 cm−1 independent of MAA concentration. Highest swelling percentage 587% was observed in case of poly(HEMA‐MAA) hydrogel synthesized using 30% of MAA while lowest swelling percentage 413% was observed in hydrogel synthesized 10% of MAA at basic pH (8.0). Scanning electron micrograph of copolymeric particles showed the irregular shape of poly(HEMA‐MAA) particles with conglomeration with each due to ionization of carboxylic groups. Insulin was radiolabeled using technetium‐99m radionuclide and the radiolabeling efficiency was found to be 99%. Poly(HEMA‐MAA) hydrogel having 60% of MAA showed the highest insulin loading efficiency of 68% while lowest 37% was observed in case of 10% MAA hydrogel. Insulin release studies showed only 35–65% of insulin was released into the medium from particles at pH 2.5 in 60 min, while insulin release was significantly higher at pH 7.4. Hypoglycemic effect of the 60 and 80 I.U./kg insulin dose loaded in poly(HEMA‐MAA) copolymeric particles were carried out in fasted diabetic rats and highest decrease in blood glucose level from 506 mg/dL to 170 mg/dL was observed within first 3 h. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

Swell-Shrinkage Behavior of Remolded Expansive Soils

The swelling behaviour of compacted expansive soils have been studied with variation in initial state. For comparison, a series of swell and shrinkage capacity laboratory tests with different initial dry densities，moisture contents and pressures have also been made with three different consistency state. Both percent swell and shrinkage are significantly influenced by the consistency state index. There is an unique relationship between percent swell and consistency state index of the soil. The percent swell-load relationship could be identified as a logarithmic relationship facilitating the prediction of ultimate percent swell under different load with a few initial results.

Cytotoxicity and biocompatibility evaluation of a poly(magnesium acrylate) hydrogel synthesized for drug delivery

We report the synthesis and characterization as well as cytotoxicity and biocompatibility studies of a poly(magnesium acrylate) hydrogel (PAMgA) developed for drug delivery applications. Two hydrogels with different mesh sizes, large and short, were synthesized (L-C PAMgA and S-C PAMgA). The hydrogels were characterized through swelling, FT-IR and DSC. Cytotoxicity in vitro was evaluated on cell line NIH-3T3 fibroblasts via direct contact and two indirect contact methods (MTT and flow citometry). Both PAMgA hydrogels exhibited low cytotoxicity with survival rates higher than 90%. To select their administration route, biocompatibility was evaluated after intraperitoneal, subcutaneous, and oral administration to mice of both hydrogels at different dose ranges. Swelling percentages obtained were 33.3 ± 4.2% and 166.7 ± 8.3% for L-C PAMgA and S-C PAMgA respectively, showing a great difference in both hydrogels. Among the administration routes assayed, the hydrogels were well tolerated after oral administration of a wide dose range (10–500 mg/kg), thereby indicating that both PAMgA hydrogels are excellent candidates for oral administration due to their in vitro biocompatibility and oral non-toxicity. These results together with the fact that their synthesis is simple and inexpensive make them good candidates for the design of oral drug delivery devices.

The use of methylene blue test for predicting swell parameters of natural clay soils

Swell behavior of clayey soils is referred to as a hidden disaster causing a great deal of damage in light hydraulic structures. In this context, it is of key importance to make a preliminary soil research and to identify soils of this nature through lab tests in order to adopt the correct design strategy. It is extremely important to have determined the swell parameters (swell percentage and swell pressure) in designing light hydraulic structures on swelling soil. In our country, these types of problems that are experienced in light hydraulic structures have been observed generally in construction works of irrigation channels carried out within the framework of Southeastern Anatolia Project. In this study, we examine the facts based on the methylene blue stain test data used in predicting swell parameters of Harran clay soils. Within the frame of the study, methylene blue tests have been carried out besides identification tests; working on undisturbed samples taken from thirty three different points by means of drilling, in an area where irrigation channels are laid intensively. Depending on relevant swell parameters, models developed are based on multiple regression analysis for practical use. In the models developed depending on dry density of soil and methylene blue value, R2 values are found to be R2 = 0.93 and R2 = 0.85 for swell percentage and swell pressure, respectively. In view of the fact that the tests that measure swell parameters are long and costly, these models would be very useful to be able to obtain a preliminary estimate rapidly. Key words: Harran clay, methylene blue stain test, swell percentage, swell pressure, multiple regression analysis.

Effect of Ionizing Radiation on the Morphological, Thermal and Mechanical Properties of Polyvinyl Alcohol/Polyethylene Glycol Blends

Blends of water—soluble polymers based on Poly vinyl alcohol (PVA) and Polyethylene glycol (PEG) have been prepared by the solution casting technique. The effect of various doses of γ-radiation on the structural properties of PVA/PEG polymer blends with all its compositions has been investigated. From the visual observation of all the blend compositions, it was found that, the best compatibility of the blend is up to 40% PVA/60%PEG. The structure–Property behavior of all the prepared blends before and after γ-irradiation was investigated by IR Spectroscopy, thermogravimetric analysis (TGA), mechanical properties and Scanning electron microscope (SEM). The gel content and the swelling behavior of the PVA/PEG blends were investigated. It was found that the gel content increases with increasing irradiation dose and PVA concentration in the blend. Swelling percent increased as the composition of PEG increased in the blend. The results obtained by FTIR analysis and SEM confirm the existence of possible interaction between PVA and PEG homopolymers. TGA of PVA/PEG blend, before and after γ-irradiation, showed that the unirradiated and irradiated PVA/PEG blends are more stable against thermal decomposition than pure PVA. Improvement in tensile mechanical properties of PVA/PEG blends was occurred.

Sustained release optimized formulation of anastrozole-loaded chitosan microspheres: in vitro and in vivo evaluation

The purpose of this study was to develop sustained release formulation of anastrozole-loaded chitosan microspheres for treatment of breast cancer. Chitosan microspheres cross-linked with two different cross-linking agents viz, tripolyphosphate (TPP) and glutaraldehyde (GA) were prepared using single emulsion (w/o) method. A reverse phase HPLC method was developed and used for quantification of drug in microspheres and rat plasma. Influence of cross-linking agents on the properties of chitosan microspheres was extensively investigated. Formulations were characterized for encapsulation efficiency (EE), compatibility of drug with excipients, particle size, surface morphology, swelling capacity, erosion and drug release profile in phosphate buffer pH 7.4. EE varied from 30.4 ± 1.2 to 69.2 ± 3.2% and mean particle size distribution ranged from 72.5 ± 0.5 to 157.9 ± 1.5 μm. SEM analysis revealed smooth and spherical nature of microspheres. TPP microspheres exhibited higher swelling capacity, percentage erosion and drug release compared to GA microspheres. Release of anastrozole (ANS) was rapid up to 4 h followed by slow release status. FTIR analysis revealed no chemical interaction between drug and polymer. DSC analysis indicated ANS trapped in the microspheres existed in amorphous form in polymer matrix. The highest correlation coefficients (R (2)) were obtained for Higuchi model, suggesting a diffusion controlled mechanism. There was significant difference in the pharmacokinetic parameters (AUC(0-∞), Kel and t(1/2)) when ANS was formulated in the form of microspheres compared to pure drug. This may be attributed to slow release rate of ANS from chitosan microspheres and was detectable in rat plasma up to 48 h which correlates well with the in vitro release data.

Alginic acid‐g‐poly(N‐vinylformamide) graft copolymer: Synthesis, characerization, swelling, and flocculation property

AbstractThe graft copolymer of N‐vinylformamide with alginic acid was synthesized by free radical polymerization using potassium peroxymonosulphate and thiourea as redox pair in inert atmosphere. The optimum conditions for maximum grafting have been determined by varying the concentrations of N‐vinylformamide, potassium peroxymonosulphate, thiourea, sulfuric acid, alginic acid as well as time duration and temperature. The grafting parameters increase up to the certain concentrations of N‐vinylformamide, potassium peroxymonosulhate, thiourea, and hydrogen ion while thereafter grafting parameters decrease. The effect of alginic acid concentration on grafting parameters has been observed to decrease continuously. It has also been found that grafting parameters increase up to certain time and temperature, respectively, and thereafter decrease. The swelling properties of graft copolymer in terms of swelling ratio and percent swelling are investigated. Flocculation property of pure and grafted sample for both coking and noncoking coals is also investigated for the treatment of coal mine waste water. The graft copolymer has been characterized by Fourier transform infrared spectroscopy as well as thermogravimetic analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Manufacturing of Wood-Plastic Composite from Completely Recycled Materials

In this study, wastes of wood cutting mills (wood flour) as well as wastes of textile industry (granules of polypropylene) were used in manufacturing wood-plastic composites. Hence, wood flour with weight percent of 30, 35 and 40 was mixed with corresponding amount of polypropylene and coupling agent, polypropylene grafted maleic anhydride in amount of 6 percent was used in whole compounds. Production was done by batch method and with employment of hot press and after preparation and cutting of specimens physical and mechanical properties of them was studied. The results showed that with increase of wood flour up to 35 percent, MOR, MOE, water absorption and thickness swelling increases but further than it mechanical and physical properties decreases. Besides, increase of wood flour up to 40 percent increased the hardness of the specimens.

Treatment of real effluents from dyeing reactor: Experimental and modeling approach by adsorption onto chitosan

This work aims to study the treatment (decolorization) of real industrial dyeing effluents originated directly from the dyeing bath, before entering the equalization tank (instead of treating the whole volume of wastewater) using chitosan beads as adsorbents. The addition of amido and imino groups on chitosan backbone through grafting reactions increased the adsorption capacity of adsorbents, while the cross-linking method made them capable of reuse for ten cycles at least without significant loss of their capacity (∼5%). The imino grafted derivative with a dosage of 5 g/L resulted in a residual dye content <1 mg/L, which is in accordance with the limitations of legislation. Swelling experiments demonstrated low swelling percentages (∼35%) for the prepared adsorbents. Equilibrium data were successfully fitted to the Langmuir–Freundlich model (L–F). Kinetic data were fitted to a proposed detailed mathematical model, based on the chemical structure of chitosan and on a valid single-component adsorbate approximation, resulting in diffusion coefficients of dyes in the triple dye mixture (both in simulated/synthetic and real effluents). A commercial form of activated carbon was used, to compare and confirm the high adsorption capacity and easy/successful regeneration of the prepared chitosan derivatives (through adsorption–desorption experiments in real effluent).

Electrically enhanced solute permeation across poly(ethylene glycol)–crosslinked poly(methyl vinyl ether-co-maleic acid) hydrogels: Effect of hydrogel crosslink density and ionic conductivity

Swelling kinetics, ionic conductivity and electrically assisted solute permeation (theophylline, methylene blue and fluorescein sodium) of poly(ethylene glycol) (PEG) crosslinked poly(methyl vinyl ether-co-maleic acid) (PMVE/MA) hydrogels are presented. The effects of PMVE/MA concentration and PEG molecular weight (MW) on swelling behaviour and network parameters were investigated in phosphate buffered saline (pH 7.4). The percentage swelling of hydrogels increased, and the crosslink density decreased, with a decrease in PMVE/MA content and with an increase in PEG MW. The ionic conductivity of the formulation was found to increase with an increase in PEG MW. The application of an electrical current led to a significant enhancement in the rate and extent of solute permeation across the swollen hydrogels. Furthermore, it was found that the extent of solute permeation enhancement following current application was dependent upon the crosslink density and ionic conductivity of the formulation. In general, a decrease in crosslink density and an increase in ionic conductivity led to a greater enhancement in solute permeation following current application. The electro-responsive nature of these hydrogels suggests that have a potential application in electrically controlled drug delivery systems.