Guar Derivatives Research Articles

Modified guar gum: An alternative source for printing of cotton fabric with reactive dye

AbstractThe alginate thickener is the thickener frequently used for reactive printing of textile. The thickener responds with reactive pigments and thus does not lead to the fabric composition becoming stiffer. In this study, we prepared oxidised natural guar gum with hydrogen peroxide, sodium hypochlorite and sodium hydroxide. All other polysaccharides comprise reactive hydroxyl units with a stronger reactivity that must be replaced if they are to be used in reactive printing. Guar derivatives were synthesised and verified using Fourier‐transform infrared (FTIR) spectroscopy. Natural thickeners, synthetic guar gum derivatives, have been employed in textile printing technique. In comparison to other synthetic thickeners, modified environmental guar gum polymer has been shown to be an ecologically friendly and low‐cost thickener. Cotton fabric printed with modified guar thickening with hydrogen peroxide has even stronger colour strength than fabric printed with sodium alginate thickener, which is highly favourable. Penetration properties, colour value, colour strength, colour fastness to washing, light and rubbing was compared with alginate thickener (readily available on the market). Guar gum thickeners showed enhanced features versus sodium alginate for reactive printing. Partially replaced guar gum is an appropriate option due to the colour and physical properties.

Rheological Study of Seawater-Based Fracturing Fluid Containing Polymer, Crosslinker, and Chelating Agent.

Freshwater is usually used in hydraulic fracturing as it is less damaging to the formation and is compatible with the chemical additives. In recent years, seawater has been the subject of extensive research to reduce freshwater consumption. The study aims to optimize the rheology of seawater-based fracturing fluid with chemical additives that reduce the formation damage. The studied formulation consists of a polymer, a crosslinker, and a chelating agent to reduce seawater hardness. We used a standard industry rheometer to perform the rheology tests. By comparing five distinct grades [hydroxypropyl guar (HPG) and carboxymethyl hydroxypropyl guar (CMHPG)], we selected the guar derivative with the best rheological performance in seawater. Five different polymers (0.6 wt %) were hydrated with seawater and freshwater to select the suitable one. Then, the best performing polymer was chosen to be tested with (1.6, 4, and 8 wt %) N, N-dicarboxymethyl glutamic acid GLDA chelating agent and 1 wt % zirconium crosslinker. In the first part, the testing parameters were 120 °C temperature, 500 psi pressure, and 100 1/s shear rate. Then, the same formulations were tested at a ramped temperature between 25 and 120 °C. We observed that higher and more stable viscosity levels can be achieved by adding the GLDA after polymer hydration. In seawater, an instantaneous crosslinking occurs once the crosslinker is added even at room temperature, while in freshwater, the crosslinker is activated by ramping the temperature. We noted that, in the presence of a crosslinker, small changes in the chelating agent concentration have a considerable impact on the fluid rheology, as demonstrated in ramped temperature results. It is observed that the viscosities are higher and more persistent at lower concentrations of GLDA than at higher concentrations. The study shows the rheological response when different chemical additives are mixed in saline water for hydraulic fracturing applications.

Green synthesis and characterization of carboxymethyl guar gum: Application in textile printing technology

AbstractThis study focusses on the synthesis of carboxymethyl guar gum (CMG) via monochloroacetic acid under alkaline conditions. The reaction conditions were also optimized during the course of experiment. Guar derivative with variable degree of substitution (DS) were prepared and were confirmed by Fourier transform infrared (FTIR) spectroscopy. The DS was determined quantitatively by titration method for each derivative. The synthesized guar gum derivatives, being the natural thickners, have been used in textile printing technology. Substituted guar gum has been proved environmental friendly thickener as compared to synthetic thickeners. Penetration properties, fixation ability, colour fastness, levelness and fabric handling was compared with alginate thickener (commercially available). Guar gum thickeners showed enhanced properties versus alginate thickener and can be used as an alternative to synthetic thickeners in view of its green, non-hazardous and economical derivatives. Guar gum is the outstanding natural thickener, stabilizer, gelling agent and could possibly be used in various industrial units including food, cosmetic, textile, oil fracturing and mining.

Laboratory Evaluation of a Low pH and Low Polymer Concentration Zirconium-CMHPG Gel System for Hydraulic Fracturing

Low pH fracturing fluids, such as the transition metal cross-linked guar derivative, can reduce the formation damage caused by clay swelling and fines migration in hydraulic fracturing treatments. ...

Dual-Polymer Hydraulic-Fracturing Fluids: A Synergy Between Polysaccharides and Polyacrylamides

Summary As exploration for oil and gas continues, it becomes necessary to produce from deeper formations, and to meet the challenge of low permeability and higher temperatures. Unconventional shale formations are addressed with slickwater fracturing fluids, owing to the shale's unique geomechanical properties. On the other hand, conventional formations require crosslinked fracturing fluids to properly enhance productivity. Guar and its derivatives have a history of success in crosslinked hydraulic–fracturing fluids. However, they require higher polymer loading to withstand higher–temperature environments. This leads to an increase in mixing time and additive requirements. Most importantly, as a result of high polymer loading, they do not break completely and thus generate residual–polymer fragments that can plug the formation and significantly reduce fracture conductivity. In this work, a new hybrid dual–polymer hydraulic–fracturing fluid was developed. The fluid consists of a guar derivative and a polyacrylamide–based synthetic polymer. Compared with conventional fracturing fluids, this new system is easily hydrated, requires fewer additives, can be mixed “on the fly,” and is capable of maintaining excellent rheological performance at low polymer loadings. The polymer mixture solutions were prepared at a total polymer concentration of 20 to 40 lbm/1,000 gal at volume ratios of 2:1, 1:1, and 1:2. The fluids were crosslinked with a metallic crosslinker and broken with an oxidizer at 300°F. Testing focused on crosslinker/polymer–ratio analysis to effectively lower loading while maintaining sufficient performance to carry proppant at this temperature. A high–pressure/high–temperature (HP/HT) rheometer was used to measure viscosity, storage modulus, and fluid–breaking performance. An HP/HT aging cell and HP/HT see–through cell were used for proppant settling. Fourier–transform infrared (FTIR) spectroscopy, Cryo scanning electron microscopy (Cryo–SEM), and an HP/HT rheometer were also used to understand the interaction. Results indicated that the dual–polymer fracturing fluid was able to generate stable viscosity at 300°F and 100 s−1 as well as generate a higher viscosity compared with the individual–polymer fracturing fluid. Also, properly understanding and tuning the crosslinker to the polymer ratio generated excellent performance at 20 lbm/1,000 gal. The two polymers formed an improved crosslinking network that enhanced proppant–carrying properties. This fluid also demonstrated a clean and controlled breaking performance with an oxidizer. Extensive experiments were pursued to evaluate the new dual–polymer system for the first time. This system exhibited a positive interaction between the polysaccharide and polyacrylamide families and generated excellent rheological properties. The major benefit of using a mixed–polymer system is reduced polymer loading. Lower loading is highly desirable because it reduces material cost, eases field operation, and potentially lowers damage to the fracture face, proppant pack, and formation.

Next-Generation Boron-Crosslinked Fracturing Fluids: Breaking the Lower Limits on Polymer Loadings

Summary Hydraulic fracturing is a robust stimulation technique that has been used for more than 60 years to help increase the recovery rate of hydrocarbons from reservoirs. Hydraulic-fracturing fluids are key components of the process. Significant efforts have been made to refine the fluids and advance new technology to help improve the economics, efficiency, and safety of the systems. Specifically, the pursuit of fluids that provide reliable and consistent performance while using lower concentrations of polymer, usually guar or a guar derivative, has been a recurrent point of emphasis in fracturing-fluid advancement. There are many advantages of using lower polymer concentrations, including lower costs, improved logistics, and introducing less polymer with its associated residues into the fracture, among others. This paper presents a new fracturing fluid that combines a next-generation boron crosslinker with a new hydroxypropyl guar (HPG) to be crosslinked with 40 to 60% less polymer than used in conventional borate-crosslinked fluids. For this fluid, HPG loadings in the range of 8 to 12 lbm/1,000 gal were used to produce boron-crosslinked stimulation fluids stable up to 200°F. Fluid-viscosity testing showed stable fracturing fluids with controlled breaking profiles at temperatures up to 180°F. Dynamic proppant-suspension testing indicated that the new fracturing fluid exhibited proppant transport equal to or better than conventional borate fluids. Regained-permeability testing with Berea sandstone cores exceeded 75% at 160°F, 85% at 180°F, and 95% at 200°F. In addition, excellent fluid cleanup was measured by retained proppant-pack conductivity with 2 lbm/ft2 of 20/40-mesh lightweight ceramic proppant. This new boron-crosslinked fluid retains the “rehealable” property and flexibility of conventional borate-crosslinked fluids; however, the polymer is crosslinked at or near the minimum concentration at which the polymer chains can entangle (and are capable of crosslinking), which is an improvement compared with conventional borate fluids. This concentration is known as the critical overlap concentration, c*, of the polymer. The use of the new crosslinking technology coupled with the new HPG allows for a two-fold advantage in terms of residue reduction. The derivatized polymer requires additional processing, yielding a cleaner polymer with less residue, and the lower polymer dosage results in a further reduction of residue compared with conventional fluids.

A REVIEW ON DERIVATIZATION OF GUAR AND STUDY OF PHARMACEUTICAL APPLICATIONS OF GUAR DERIVATIVES

Guar gum is a naturally occurring alternating co-polymer derived from the seeds of Cyamopsis tetragonoloba. Guar has high intrinsic viscosity but very poor interaction coefficient. Guar dispersions lose viscosity upon standing. Guar has been derivatized to hydroxyalkyl, alkali carboxyalkyl and quaternary ammonium guar. Derivatization of guar enhances solution stability, clarity of dispersion and resistance to microbial attack. Derivatives of guar have immense pharmaceutical and cosmetic applications. The present review focuses on the various methodologies available for effecting derivatization of guar and also covers the specific application case studies in pharmaceutical and cosmeceutical fields. The authors opine that guar derivatives such as hydroxypropyl guar, sodium carboxymethyl guar and cationic guar are the prominent ones and shall be accorded an official status.

Certain Rheological Aspects of Functionalized Guar Gum

Guar gum and its derivatives are highly important industrial hydrocolloids as they find applications in various industrial sectors. Guar is a polymer of high molecular weight and its aqueous solutions exhibit unique rheological properties, which has led to its wide acceptance by the industry. In certain industrial applications low molecular weight guar and its derivatives are needed, and conventionally chemical depolymerisation of guar is carried out for this purpose. Radiation processing is a novel and green technology for carrying out depolymerization and can be an ideal substitute for chemical depolymerisation technique. In order to study the effect of radiation on guar derivatives, three types of derivatives have been taken in the present study: carboxymethyl, hydroxyethyl, and methyl guar. The effect of 1–50 KGy radiation dose on the rheological behavior of these derivatives has been studied, and the results have been described in the present paper. The effect on storage and loss modulus with respect to frequency and effect on viscosity with respect to shear rate have been discussed in detail.

Functional galactomannan platform from convenient esterification in imidazolium-based ionic liquids

Various imidazolium-based ionic liquids (ILs), considered as “green” solvents, were used as efficient solvents for galactomannan and more specifically for guar gums of high molecular weight. FT-IR as well as the high activation energies reflect hydrogen bonds between the guar backbone and anions of ILs which act as chaotropic agents. Importantly, the dissolution was conducted under mild conditions which allowed the preservation of the chain integrity, as proved by SEC, FT-IR and ATG analyses collected for guar regenerated from IL solutions. For the first time, ILs were exploited as reactional media in which tailor-made guar derivatives were synthesized through a direct and homogeneous esterification with a variety of acid chlorides. We demonstrated that the degree of substitution of guar can be varied by experimental conditions and that it is necessary to adjust these conditions as a function of the esterifying reagent structure. The use of hexanoyl chloride imparted emulsifying properties to guar and esterification with acryloyl chloride and 2-chloropropionyl chloride allowed generation of reactive precursors such as macromonomer and macroinitiator, respectively. The reactivity of the guar macromonomer was assessed through a thermal cross-linking radical copolymerisation, which led to guar gel with solid-like behaviour.

Encapsulation of Pigment Using Natural Polysaccharides

With a view to developing UV curable systems from renewable biocompatible raw materials, the present work deals with the encapsulation of pigments with polysaccharide derivatives that can undergo crosslinking upon exposure to UV radiation. Maleate ester derivatives were prepared in anhydrous conditions using maleic anhydride in the presence of pyridine. Encapsulation of the pigment core in the prepared UV curable systems occurred by applying the prepared guar derivative as a shell material in a UV curable formulation that can be induced by a photoinitiator. Encapsulation is done by the o/w/o miniemulsion polymerization technique. In another approach, and for the sake of comparison, microencapsulation was performed via chemical crosslinking of the prepared guar maleate derivative in a W/O emulsion .The resultant nanocapsules were characterized using FTIR, DSC, and SEM. The nanocapsules were spherical with average particle size of 100 nm.

Compatibility testing and rheological characterization in development of novel in situ guar gum-based ophthalmic dosage form

Guar gum is derived from the seeds of Cyamopsis tetragonolobus. Guar has certain drawbacks such as uncontrolled rate of hydration, fall in viscosity on storage, susceptibility to microbial degradation, and turbidity in aqueous dispersion. Many of these drawbacks can be overcome by using guar derivatives. Guar derivatives upon contact with water hydrate to form hydrogels for controlled-release mechanism and show stimuli-responsive changes in their structural network, and hence, the drug release. The present investigation aims at screening guar derivative (hydroxyl propyl guar) during preformulation stage by spectral (FTIR spectroscopy), thermal (differential scanning calorimetry (DSC)), isothermal (HPLC technique), and rheological characterization for the development of stable in situ ophthalmic dosage using linezolid as the model drug.

Cationic Liposome Colloidal Stability in the Presence of Guar Derivatives Suggests Depletion Interactions May be Operative in Artificial Tears

The colloidal stability of cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) liposomes was measured in the presence of guar, carboxymethyl guar, hydroxypropyl guar (HPG), and in mixtures of HPG with boric acid. Carboxymethyl guar induced DOTAP aggregation, presumably by bridging flocculation. The interaction with HPG-borate, an anionic polyelectrolyte with labile charge groups, depended on ionic strength. Without added salt, HPG-borate (pH 9.2) adsorbed on the liposomes and destabilized them. In contrast, in 0.1 M NaCl, HPG-borate did not adsorb onto the liposomes. HPG, HPG-borate, and guar induced depletion flocculation of the liposomes at high polymer concentration. Depletion flocculation may be an important mechanism when HPG is employed in artificial tear formulations.

Rheological properties of guar and its methyl, hydroxypropyl and hydroxypropyl-methyl derivatives in semidilute and concentrated aqueous solutions

We report on a comparative study of the rheological properties of guar [GG], methyl guar [MG], hydroxypropyl guar [HPG] and hydroxypropyl-methyl guar [MHPG] polymers aqueous solutions in semidilute (both unentangled and entangled) and concentrated regimes, using oscillatory and steady-shear techniques. In the dilute regime, molecular weights and radii of gyration have been investigated by means of light scattering measurements.Data obtained from steady-shear rheology were satisfactorily analyzed according to Cross model and the effects of polymer concentration and temperature on the rheological behaviour of guar and guar derivatives have been investigated and discussed in terms of rheological parameters, such as the zero-shear viscosity η0, the characteristic time τ and critical coil-overlap concentration C∗.The storage and loss moduli of guar and guar derivatives aqueous solutions have been measured using angular frequencies in the range between 10−3 and 10rad/s. The data have been analyzed using the “blob” model for semidilute solutions and the scaling approach proposed by Rubinstein, Dobrynin and Colby for concentrated solutions. These rheological parameters obey a time–concentration superposition principle, so that master curves can be constructed over a wide frequency range. Moreover, we show that, at lower temperatures, these systems behave as thermo-rheological simple systems, in that the oscillatory shear response at different temperatures can be superimposed according to the empirical time–temperature superposition principle. Although these systems can be conveniently described within a unifying scaling model, the behaviour of guar derivatives are somewhat different. At higher temperatures, relatively small deviations from the scaling behaviour of the storage modulus of MG and MHPG polymers were observed. These findings can be justified by a structural re-organization of the macromolecular network, due to the hydrophobic interactions.

Crosslinking of Guar and Guar Derivatives

SummaryCrosslinking of guar and guar derivatives has played a major role in improving stimulation of oil and gas wells. While crosslinking has been used for a number of years, many facets of crosslinked systems are still not well understood. Part of the problem is that the traditional methods of determining the properties of crosslinked fluids work well for obtaining the data necessary for treatment design, but yield little insight into the nature of the crosslinked system. A good example of this is found in the development of low polymer concentration crosslinked gels. These gels are important because they lower costs and help to minimize formation damage. In this paper, methods for predicting crosslinkability at low concentrations are reported.The polymer literature is filled with methods for characterizing polymer solutions almost none of which find wide use in the development of crosslinked fracturing fluids. Dawson et al. (2000) first reported that the concentration at which a polymer solution transitions from dilute to semidilute could be used as a method for determining the potential for low concentration crosslinking in guar or guar-derivative solutions. To test this assertion, we have conducted a series of experiments that not only shows that the dilute-semidilute transition concentration is an important indicator for the polymers used in this study, but also presents a framework for exploring the potential of other polymer systems. These experiments show conclusively that low-polymer concentration crosslinking is strongly related to the value of the critical overlap concentration, c*. Both the critical overlap concentration and the critical crosslinking concentration increase in the order guar-3 < CMG < CMHPG < guar < HPG. In addition, we show that the critical crosslinking concentration for the range of polymer-crosslinking systems studied is correlated to the critical overlap concentration (ccc = 1.8(c*)0.77). A strong case is presented for the ability to crosslink at low concentrations is a strong function of the polymer type and a weak function of the crosslinker type.

Hydrophobic guar gum derivatives prepared by controlled grafting processes

AbstractIntroduction of polyalkoxyalkyleneamide grafts to guar gum produces a new water soluble guar derivative. Modification of either guar gum or hydroxyopropyl guar is achieved in a three‐step process: carboxymethylation with sodium chloroacetate, esterification with dimethyl sulfate (DMS) and amidation with a series of polyalkoxyalkyleneamines. The process was followed using infrared spectroscopy; the grafted guar derivatives were characterized using 1H NMR. A series of hydroxypropyl guar (HPR) derivatives with degrees of carboxymethylations ranging from 0.2–0.3 were modified with polyalkoxyalkyleneamines with molecular weights ranging from 300 to 3000. The ratio of oxypropylene to oxoethylene units in the polyalkoxyalkyleneamines was varied from 9/1 to 8/58 to adjust the hydrophobicity of the grafts. Aqueous solutions of the graft copolymers exhibit viscosities one to two orders of magnitude lower than the corresponding solutions of the parent guar gum. Copyright © 2007 John Wiley & Sons, Ltd.

Hydrophobic guar gum derivatives prepared by controlled grafting processes–Part II: rheological and degradation properties toward fracturing fluids applications

AbstractIntroduction of polyalkoxyalkyleneamide grafts to guar gum produces new water soluble guar derivatives as described in an earlier publication.10 In this paper, the rhelogical behavior of these products was explored in more detail at 25 and 65°C. In addition, the viscosity was measured at high temperatures (90 and 120°C) and pressure (150 psi) to partially simulate the down hole conditions of oil wells. Upon treatment with zirconium lactate, the cross‐linked hydrophobically‐modified CMG derivatives exhibited better high‐temperature stability and higher gel viscosities than the corresponding CMHPG derivatives. The cross‐linked gel viscosities indicate that gels will be capable of supporting a high proppant carrying capacity. To facilitate removal of the gels from the formation, the hydrophobically modified derivatives were treated with an enzyme breaker system which produced fragments capable of producing stable emulsions when extracted with toluene. Thus, the clean up process will be enhanced by emulsification of the gel fragments produced by the gel hydrolysis. The low viscosities of the linear derivatives, the rapid formation of high viscosity gels upon cross‐linking and generation of emulsifiers during the gel removal suggest that these new derivatives are good candidates for fracturing fluid applications. Copyright © 2007 John Wiley & Sons, Ltd.

Influence of Different Guar Thickeners on Interactions with Monoreactive Dyes and Cellulose Fibers

The suitability of carboxymethyl guar derivatives as thickeners in reactive printing of viscose fabrics is investigated. We show the influence of different guar thickeners on the stiffness of viscose fabric printed with monoreactive vinylsulphone dyes. The conse quences of interactions that are proportional to the bending rigidity of prints are confirmed with the quantity of residual add-on and with IR spectroscopy. The interactions depend on the macromolecular structure of the guar thickener, its degree of polydispersity, and the number of free reactive OH groups able to react with guar molecules. We conclude that higher bending rigidity is the result of physicochemical binding of guar molecules on the viscose fibers by means of hydrogen and/or ether bonds by free OH groups. Hydroxyl groups of monoreactive dyes also increase bending rigidity as a result of chemical interaction with the OH groups of guar and viscose.

POLYMER EFFECTS ON THE HYDRAULIC CONDUCTIVITY OF SALINE AND SODIC SOIL CONDITIONS

Water used for irrigation in many semiarid regions of the world contains high levels of salinity and/or sodicity which affect hydraulic conductivity. Polymers mixed with the irrigation water may affect hydraulic conductivity. The hydraulic conductivity of a Haplic Durixeralfs soil classified as Arlington sandy loam was measured in disturbed laboratory columns using waters of various electrolyte concentrations, sodium adsorption ratios, and with or without a polymer. Cationic polysaccharide, guar derivative (CP-14), and very low negative charge polyacrylamide (2J) polymers were investigated. After passing several pore volumes of water through the soil, the soil was removed from the column, dried, sieved, and repacked into the columns. The hydraulic conductivity was then measured using city of Riverside, CA tap water. The greatest increase in hydraulic conductivity with CP-14 compared to the control occurred with SAR equal to 5 and at the two highest electrolyte concentrations. The 2J polymer was most effective in increasing hydraulic conductivity when it was added to the high electrolyte solution. During the second run with tap water, the hydraulic conductivity for no polymer and CP-14 treatments were similar to each other and less than the 2J treatment. The polyacrylamide apparently promoted aggregate stability to the soil when it is dried, whereas the guar did not. This behavior may be caused by the high molecular weight of the polyacrylamide.

Polymers as Soil Conditioners Under Consecutive Irrigations and Rainfall

AbstractLow water infiltration caused by crust formation during rain or sprinkler irrigation is a significant problem in some arid and semiarid regions. Polymers may be applied in irrigation water through a sprinkler system, but must be applied directly to the soil under rainfall conditions. The objectives of this rainfall simulator study were to: (i) determine the effect of drying of crusted vermiculitic soil on the subsequent crust properties and infiltration rate (IR) values, (ii) determine the effect of polymers applied at low concentration in irrigation water of two qualities on the IR under consecutive water applications, and (iii) determine the effectiveness of polymer application to the soil as would be required under rainfall conditions. Two cationic polysaccharide guar derivatives having a higher (HCCP) and a lower (LCCP) charge density and a polyacrylamide (PAM) with a low negative charge density were used in the study. Applications of polymers with the sprinkler water maintain IR in the order HCCP > LCCP > PAM > untreated. Except for PAM, the polymer applications were relatively ineffective in subsequent sprinkler applications with plain water applied with impact energy. The beneficial effects were preserved under water application without impact energy. Spraying concentrated polymer solutions on the soil surface was not effective in preventing crust formation by following rain events except for the case when LCCP was sprayed on in a CaCl2 solution. The results are explained on the basis of polymer adsorption and penetration into the soil surface layer and aggregates.

Effect of Polysaccharides, Clay Dispersion, and Impact Energy on Water Infiltration

AbstractEffects of clay dispersion, impact energy of water drops, and chemical amendments on crust formation and infiltration rate (IR) of Haplic Durixeralf soil were studied using a sprinkler infiltrometer. The soil was subjected to two impact energies, high energy = 240 J m−2 h−1 and low energy = 0, and to three waters: (i) distilled water [DW, electrical conductivity (EC) < 0.05 dS m−1], (ii) saline water (SW, EC = 5.0 dS m−1), and (iii) regular water (RW, EC = 1.0 dS m−1). The chemical amendments, polysaccharides, guar derivatives were supplied with the DW and RW and with high impact energy. Crust formation by the impact energy was found as a dominant factor in the IR reduction. This factor reduced the total soil infiltration capacity by more than 40%. Conversely, clay dispersion in the soil surface reduced the total soil infiltration capacity by 24%. Likewise, it was found that clay dispersion in the soil surface decreased the hydraulic conductivity of the crust and sharply increased its hydraulic resistance. The polymers had an amendatory effect on the IR. The polymers apparently adsorbed on the particle surfaces and acted as a cementing material holding primary particles together against the destructive forces of the water drops. The order of the maximum effect of the chemical amendments (0.01 kg m−3), that were supplied in DW, on the maintenance of IR was: high charge cationic polymer (HCCP) > low charge cationic polymer (LCCP) ≫ nonionic polymer > anionic polymer (had no effect). A concentration of 0.01 kg m−3 of HCCP and LCCP in RW prevented crust formation and preserved the high initial IR of the soil throughout the water application period. The HCCP and LCCP under sprinkled DW and RW conditions apparently adsorbed at the soil surface and did not move with the water into the soil layer.