Synthesis and characterization of grafted carboxymethyl guar gum

Graft copolymers of carboxymethyl guar gum (CMGG) and polyacrylamide (PAM) have been synthesized by grafting polyacrylamide chains onto carboxymethyl guar gum backbone using a ceric‐ion‐induced solution polymerization technique. By varying the amount of initiator, three different grades of graft copolymers are synthesized. The characterization of graft copolymer is carried out by FTIR, NMR, intrinsic viscosity measurement, SEM, SLS, DTG, and rheology. A comparison of flocculation efficiency of CMGG and its graft copolymer shows that the graft copolymer exhibits better flocculation performance. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Grafting of polyacrylonitrile onto guar gum under microwave irradiation

Using microwave (MW) irradiation grafting of polyacrylonitrile (PAN) onto guar gum in water was done without using any radical initiator or catalyst within a very short reaction time. The extent of grafting could be adjusted by controlling the reaction conditions and maximum percentage grafting (%G) of about 188% was obtained under optimum conditions in 1.66 min. The average molecular weight of the grafted PAN chains and water‐retention power of the alkali hydrolyzed MW‐grafted gums were also determined and compared with those of the conventionally synthesized (cs) graft copolymer. A representative MW‐grafted copolymer, guar‐g‐polyacrylonitrile was characterized by IR, NMR, XRD, TGA, and elemental analysis. A plausible mechanism for the grafting under MW was proposed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1569–1575, 2004     

瓜胶及其衍生物在药物控制释放领域的研究进展

介绍了官能团衍生化、接枝共聚、交联等瓜胶衍生物的制备方法及影响因素、瓜胶及其衍生物在药物控制释放领域的应用现状,并指出改性瓜胶具有比原粉更好的药物控制释放效果,因此经过配方设计,瓜胶及其衍生物有望成为药物控制释放尤其是靶向结肠给药领域的理想载体。     

Chemical modification of cashew gum with acrylamide using an ultrasound‐assisted method

A flocculant based on cashew gum (CG) grafted with polyacrylamide (PAM) was synthesized using potassium persulfate as the chemical initiator and ultrasound energy. The intrinsic viscosity, hydrodynamic radius, and grafting efficiency of the grafted copolymers (CG‐g‐PAM) were investigated at different monomer and initiator concentrations. The CG‐g‐PAM copolymers were evaluated in kaolin suspension and river water by using jar test procedure comparatively to a commercial flocculant (Flonex‐9045). Ultrasonication resulted in reduced reaction time and high grafting efficiency. The reaction gel point was reached within 10 min and the grafting efficiency was dependent on the acrylamide concentration. The grafted copolymer CG‐g‐PAM‐15²⁸⁵ obtained with 0.285 mmol of initiator showed higher hydrodynamic radius, with flocculation efficacy of 96% comparable with the flocculant Flonex‐9045. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43634.     

Preparation and swelling characteristics of a superabsorbent nanocomposite based on natural guar gum and cation‐modified vermiculite

A series of novel superabsorbent nanocomposites were prepared by the solution radical polymerization of natural guar gum (GG), partially neutralized acrylic acid [sodium acrylate (NaA)], and cation‐exchanged vermiculite (Mⁿ⁺‐VMT) with ammonium persulfate as the initiator in the presence of the crosslinking agent N,N′‐methylene‐bis‐acrylamide. Fourier transform infrared analysis revealed that NaA was grafted onto the GG chains and that Mⁿ⁺‐VMT participated in the polymerization. X‐ray diffraction results showed that the occurrence of the cation‐exchange process changed the interlayer gap of vermiculite (VMT) and that Mⁿ⁺‐VMT was exfoliated during polymerization to form a nanocomposite. The exfoliated VMT led to better dispersion in the GG‐g‐poly(sodium acrylate) matrix, as shown by scanning electron microscopy and transmission electron microscopy analysis. Mⁿ⁺‐VMT improved the water absorption of the nanocomposite more remarkably than raw VMT, and Al³⁺‐VMT enhanced the water absorption to the highest degree. The nanocomposite exhibited intriguing overshooting swelling characteristics in a multivalent saline solution and acidic pH solution and showed switching pH‐responsive behaviors in buffer solutions between pH 2 and pH 7.2. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Studies on graft copolymerization of 4‐vinylpyridine onto guar gum

Graft copolymerization of 4‐vinylpyridine (4‐VP) onto guar gum (GOH) using potassium monopersulfate (PMS)/thioacetamide (TAA) as a redox pair was studied in an aqueous medium under inert atmosphere. The concentration of potassium monopersulfate and thioacetamide should be 1.0 × 10^?2 and 5.0 × 10^?3 mol dm^?3, respectively, for highest grafting ratio and efficiency. Efficient grafting was observed at 19.25 × 10^?2 and 4.87 × 10^?2 mol dm^?3 concentration of 4‐vinylpyridine and sulfuric acid, respectively. The optimum temperature for grafting is 30°C. As the time period of reaction is increased, the grafting ratio increases, whereas efficiency decreases. The plausible mechanism of grafting has been suggested. A sample of guar gum and guar‐ g‐4‐vinylpyridine were subjected to thermogravimetric analysis with the objective of studying the effect of grafting 4‐vinylpyridine on the thermal stability of guar gum. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2380–2385, 2002     

Synthesis,characterization, and flocculation characteristics of hydrolyzed and unhydrolyzed polyacrylamide grafted xanthan gum

The partial hydrolysis of xanthan gum‐g‐polyacrylamide was carried out in alkaline medium. Four grades of partially hydrolyzed products were synthesized by varying the reaction parameters. The neutralization equivalents of these products were determined by titration with standard sodium hydroxide solution. The flocculation characteristics of all the hydrolyzed graft copolymers and the unhydrolyzed xanthan gum‐g‐polyacrylamide were determined in 5 wt % iron ore and kaolin suspensions. The partially hydrolyzed product with neutralization equivalent of 1000 g showed better performance than that of other partially hydrolyzed products, but all hydrolyzed products exhibited poorer performance than that of the unhydrolyzed product in flocculation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1411–1419, 2004     

Graft copolymerization of acrylic acid onto guar gum

The graft copolymerization of acrylic acid (AA) onto guar gum (GOH) was carried out by a peroxydiphosphate (PDP)–silver(I) system. Grafting ratio, efficiency, add‐on, and conversion increase upon increasing the concentration of PDP and acrylic acid, whereas they decrease upon increasing the concentration of guar gum. Upon increasing the concentration of silver and hydrogen ions up to 2.0 × 10⁻³ and 4.87 × 10⁻² mol dm⁻³, respectively, the grafting ratio and efficiency increase but decrease upon further increasing the concentration. The increase in temperature from 30 to 45°C increases the grafting ratio but the conversion efficiency decreases. The optimum time period for graft copolymerization was found to be 2 h. The graft copolymers were characterized by infrared spectroscopy and thermogravimetric analysis. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 39–44, 2000     

Ceric ion‐induced graft copolymerization of acrylamide on cationic guar gum at low temperature

The solution polymerization of acrylamide (AM) on cationic guar gum (CGG) under nitrogen atmosphere using ceric ammonium sulfate (CAS) as the initiator has been realized. The effects of monomer concentration and reaction temperature on grafting conversion, grafting ratio, and grafting efficiency (GE) have been studied. The optimal conditions such as 1.3 mol of AM monomer and 2.2 × 10^?4 mol of CAS have been adopted to produce grafted copolymer (CGG1‐g‐PAM) of high GE of more than 95% at 10°C. The rates of polymerization (R_p) and rates of graft copolymerization (R_g) are enhanced with increase in temperature (<35°C).The R_p is enhanced from 0.43 × 10^?4 mol L^?1 s^?1 for GG‐g‐PAM to 2.53 × 10^?4 mol L^?1 s^?1 for CGG1‐g‐PAM (CGG1, degree of substitute (DS) = 0.007), and R_g from 0.42 × 10^?4 to 2.00 × 10^?4 mol L^?1 s^?1 at 10°C. The apparent activation energy is decreased from 32.27 kJ mol^?1 for GG‐g‐PAM to 8.09 kJ mol^?1 for CGG1‐g‐PAM, which indicates CGG has higher reactivity than unmodified GG ranging from 10 to 50°C. Increase of DS of CGG will lead to slow improvement of the polymerization rates and a hypothetical mechanism is put forward. The grafted copolymer has been characterized by infrared spectroscopy, thermal analysis, and scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3715–3722, 2007     

Synthesis,characterization, and flocculation characteristics of polyacrylamide‐grafted glycogen

The synthesis of glycogen‐g‐polyacrylamide (Gly‐g‐PAM) was carried out by a ceric ion‐induced solution polymerization technique. Six grades of graft copolymers were synthesized by the variation of catalyst and monomer concentrations. These graft copolymers were characterized by intrinsic viscosity measurements, FTIR spectroscopy, and X‐ray diffraction techniques. Flocculation performance of these graft copolymers were done in kaolin suspension. Of the above grades, the graft copolymer Gly‐g‐PAM 5, which has longer PAM chains, showed best flocculation performance. The flocculation performance of the graft copolymer was compared with commercial flocculants and other PAM‐grafted flocculants developed so far in the authors' laboratory. In all the cases, it was found that the graft copolymer performed the best. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 773–778, 2007     

Synthesis,characterization, flocculation,and rheological characteristics of hydrolyzed and unhydrolyzed polyacrylamide‐grafted poly(vinyl alcohol)

Graft copolymers of poly(vinyl alcohol) and polyacrylamide (PVA‐g‐PAM) were synthesized using a ceric ion–induced solution polymerization technique at 28°C. Three grades of graft copolymers were synthesized with varying acrylamide concentrations. Three grades of hydrolyzed products of PVA‐g‐PAM were synthesized with varying concentrations of sodium hydroxide solution. Hydrolyzed and unhydrolyzed PVA‐g‐PAM were characterized by viscometry, X‐ray diffractometry, infrared spectroscopy, and thermal analysis. Rheological investigation was also carried out on the aqueous solutions of various samples. The flocculation characteristics of various materials were investigated by the use of jar and settling tests in 0.25 and 5 wt %, respectively, using kaolin and iron ore suspensions. Among the series of graft copolymers, the one with fewest but longest PAM chains showed superior performance. The flocculation characteristics of the best‐performing graft copolymer were compared with those of various commercially available flocculants in the two suspensions under investigation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2109–2122, 2006     

An investigation of the flocculation characteristics of polyacrylamide‐grafted chitosan

To investigate the flocculation characteristics of polyacrylamide (PAM)‐grafted chitosan, a series of PAM‐grafted chitosan copolymer (Chito‐g‐PAM1 to Chito‐g‐PAM4) have been synthesized by ceric ammonium nitrate‐induced solution polymerization technique in nitrogen atmosphere. The flocculation characteristics of the polymer samples (PAM, grafted and ungrafted chitosan) were studied by settling test and jar test methods in the colloidal suspensions of kaolin, iron ore, silica, and bentonite powder. It was found that the settling performance of Chito‐g‐PAM3 is best among the polymer samples. The jar test results indicate that the ungrafted chitosan has better water clarifying performance than both the PAM and grafted chitosan. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Sorption,diffusion, and pervaporation separation of water–acetic acid mixtures through the blend membranes of sodium alginate and guar gum‐grafted‐polyacrylamide

Nonporous homogeneous dense membranes were prepared from the blends of sodium alginate (Na–Alg) with guar gum‐grafted polyacrylamide (GG‐g‐PAAm) in the ratios of 3 : 1 and 1 : 1 and these were tested for the pervaporation separation of water–acetic acid mixtures at 30°C. Blend compatibility was studied in solution by measuring the viscosity and the speed of sound. Membranes were crosslinked by glutaraldehyde. The GG‐g‐PAAm polymer and the crosslinked blend membranes were characterized by Fourier transform infrared spectra. High separation selectivity was exhibited by the pure Na–Alg membrane for water–acetic acid (HAc) mixtures containing 20 mass % of water. The permeation flux increased with increasing mass percent of water in the feed as well as with an increase in the amount of GG‐g‐PAAm in the blend, but separation selectivity decreased. Sorption selectivity was higher for the Na–Alg membrane than for the blend membranes, but it decreased with increasing mass percent of GG‐g‐PAAm in the blends. Diffusion selectivity values vary systematically with the blend composition, but not with the amount of water in the feed. Diffusion coefficients of the water–HAc mixtures were calculated from Fick's equation using sorption data and compared with those calculated from flux values obtained in pervaporation experiments. The Arrhenius activation parameters were calculated for the 20 mass % of water in the feed using flux and diffusion data obtained at 30, 40, and 50°C. The diffusion and pervaporation results are explained in terms of solution–diffusion concepts. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 259–272, 2002     

Thermal stability enhancement of guar-based hydraulic fracturing fluids by phosphate treatment

Guar gum (GG), along with its derivatives [e.g., hydroxypropyl guar (HPG)], is an important thickening agent in the hydraulic fracturing fluid system. However, as the oil reservoir gets deeper, GG is unable to tolerate the elevated temperature. In this study, the thermal stability of GG and HPG can be increased up to 95% and 80%, respectively, when phosphates are used as thermal stabilizer. The thermal stability is highest when the usage of phosphate is 1.84 mmol L⁻¹ KH₂PO₄ for GG and 2.27 mmol L⁻¹ K₂HPO₄ for HPG and the pH is 6.25–6.90 for GG and 6.25–8.75 for HPG. Furthermore, the heated GG with phosphate treatment demonstrates excellent crosslinking ability, which suggests that phosphate can be a good alternative for current thermal stabilizers and has potential application in the high-temperature formation oil or gas production. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47119.     

微波辅助阳离子瓜尔胶的合成研究

以瓜尔胶为原料,3-氯-2-羟丙基三甲基氯化铵为醚化剂,氢氧化钠为催化剂,异丙醇作为溶剂,利用微波辅助合成了阳离子瓜尔胶。结果表明,在瓜尔胶醚化过程中使用微波辅助,反应时间是传统阳离子瓜尔胶合成方法的1/6,提高了反应效率。最佳反应条件为:溶剂选用85%异丙醇,微波功率300 W,微波辐射时间为30 min,反应温度40℃,醚化剂与瓜尔胶的物质的量比为0.25,碱与瓜尔胶的物质的量比为0.20。产物水溶性很好,可与表面活性剂复配。     

Etherification optimization for preparing partially hydrolized hydroxypropylated guar gum and its properties

The partially hydrolized hydroxypropylated guar gum (PHHGG) was prepared using GG as the raw material, hydrochloric acid as the hydrolysis agent, epoxy propane as the etherifying agent, ethanol as the solvent to obtain better property combination. The effect of the reaction temperature, reaction time, and amounts of sodium hydroxide, ethanol, and epoxy propane on the substitution degree of the partially hydrolized hydroxypropylated GG was investigated. These process parameters were optimized by the orthogonal test. Using polarized light microscopy, infrared spectrometer, differential scanning calorimetry, and thermogravimetric analyzer, the appearance, structure, and thermal property of the partially hydrolized hydroxypropylated GG (PHHGG) were observed and measured. The results indicated that the best process conditions for preparing the PHHGG were: reaction temperature = 60°C, reaction time = 12 h, amount of sodium hydroxide = 1.2%, amount of ethanol = 60%. The acid resistance and alkali resistance of GG were obviously improved by the acidolysis and hydroxypropylation. The particle appearance of GG was a thin strip after it was hydrolized by acid and hydroxypropylated by epoxy propane. The acidolysis increased the melting onset temperature, peak temperature, and end temperature of GG but the hydroxypropylation decreased them. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40489.     

阳离子瓜尔胶与聚丙烯酰胺联合调理污泥

采用改性天然产物阳离子瓜尔胶（CGG）和聚丙烯酰胺（PAM）调理污泥,研究它们对城市生活污泥的沉降和脱水效果,分析两种药剂以不同投加量和不同投加顺序对污泥毛细吸水时间（CST）、30 min污泥沉降比（SV）、离心后污泥含水率及离心后污泥上清液透光率的影响。结果表明：CGG能够提高污泥的脱水性和沉降性,与PAM复合使用时,效果更显著。试验得出CGG和PAM用量分别为900 mg/L和150 mg/L,投加方式为先加阳离子瓜尔胶,搅拌后加PAM,污泥脱水和沉降效果较好,SV比原污泥下降了17.2%,CST由470 s下降到14 s,上清液透光率达到96.1%。     

Ceric ammonium sulfate/sodium disulfite initiated grafting of acrylamide on to Cassia reticulata seed gum

Ceric ammonium sulfate/sodium disulfite redox system was evaluated for the poly(acrylamide) (PAM) grafting on to Cassia reticulata (CR) seed gum. Grafting conditions were optimized and the maximum %Grafting (%G) and %Efficiency (%E) achieved were 152 and 97.2%, respectively, using [disulfite] 0.005M; [ceric ammonium sulfate] 0.026M; [acrylamide] 0.11M; [gum] 0.125 g/25mL at 40 ± 0.2°C. Representative CR‐grafted gum (CRPAM) was characterized by Fourier transform infrared spectrometry (FTIR), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). Under identical conditions, the redox initiator could result 142.6 %G and 91.2 %E on to guar gum (GG). Various physical properties of the CR gum/grafted CR gum, such as viscosity, water retention, and saline retention, were studied and compared with GG/grafted GG to find out the potential industrial use of CR gum and PAM‐grafted‐CR gum. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel biodegradable flocculating agents prepared by grafting polyacrylamide to Konjac

Grafting copolymers of polyacrylamide (PAM) with Konjac gum (KGM) have been synthesized using ceric‐ion‐induced initiation technique. The copolymers were characterized using several instrumental techniques, including infrared (IR) spectroscopy, elementary analysis, scanning electron microscopy (SEM), size exclusion chromatography (SEC) analysis, and intrinsic viscosity to confirm the success of grafting. The flocculation performance of graft copolymers was characterized by two methods. One was to study the relationship between the flocculants doses in kaolin suspension and the supernatant transmittance, and the other is to examine the time dependence of sediment height of kaolin suspensions. It was found that the graft copolymer is better than KGM and pure PAM. Biodegradation behavior was testified by monitoring the decay of relative viscosities, and approved by KGM ether bonds breaking in IR spectra and the molecule weight reduction in SEC analysis. The results indicate that the grafted KGM copolymers have improved both, flocculation performance and better biodegradable properties than the unmodified parent KGM and pure PAM. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Graft polymerization of methyl methacrylate onto guar gum with ceric ammonium sulfate/dextrose redox pair

The effect of different reaction conditions on the grafting of methyl methacrylate (MMA) onto guar gum (GG) has been studied in detail. The grafting efficiency was optimal under the following conditions: MMA at 1.13 mol/L; ceric ammonium sulfate at 6.32 × 10^?3 mol/L; dextrose monohydrate at 2.428 × 10^?3 mol/L; GG at 4 g/L; temperature at 50°C; and time at 210 min. Fourier transform infrared spectroscopy was used for the confirmation of copolymer formation. Thermogravimetric analysis of GG and a representative graft copolymer were studied. A probable mechanism of grafting has been suggested. The biodegradability of the resulted copolymer was evaluated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3520–3525, 2001