Gums solution compatibility

Locust bean gum is not completely soluble in cold water it must be heated to 80°C and cooled to attain a stable solution that has high viscosity at low concentrations. The gum is compatible with other plant gums and the viscosity of solutions is not appreciably affected by pH or salts. 

We have already mentioned that xanthan gum solutions are tolerant to both acids and bases. Solutions of xanthan gum also have excellent compatibility with many surfactants, water-miscible solvents, and other thickeners. As an anionic polysaccharide, xanthan gum is most stable with anionic surfactants (up to 20% active), nonionic surfactants (up to 40% active), and amphoteric surfactants (up to... 

Xanthan gum will dissolve in acids such as 5% acetic acid and remain stable for several months unless the temperature is elevated. Also, xanthan gum is soluble directly in 5% sodium hydroxide solutions. Sodium hydroxide solutions of 0-15% can be thickened, provided the gum is pre-dissolved in water prior to adding the sodium hydroxide solution. These highly alkaline, thickened solutions have exceptional viscosity stability. Water miscible compounds such as ethanol are compatible with xanthan gum solutions up to concentrations of 50%. Solutions, emulsions, and gels that contain xanthan gum have excellent freeze-thaw resistance and many applications in the food industry. 

Solutions of locust bean gum have a pH between 5 and 7 and are highly viscous like those of guar gum. They behave similarly toward pH changes (stable over pH 3-11), borate ions, and organic solvents. Locust bean gum is compatible with gelatin, starch, and other plant gums (see guar gum). 

CMC is compatible with most water-soluble nonionic gums over a wide range of concentrations. When a solution of CMC is blended with a solution of a nonionic polymer such as hydroxyethjlceUulose or hydroxypropylceUulose, a synergistic effect on viscosity is usuaUy observed. Such blends... 

HEC is generally compatible with other ceUulosic water-soluble polymers to give clear, homogeneous solutions. When mixed with an anionic polymer such as CMC, however, interactions between the two polymers may result in synergistic behavior, ie, viscosities higher than predicted and calculated. HEC has excellent compatibiUty with natural gums. 

HPC is compatible with many natural and synthetic water-soluble polymers and gums (50). Generally, blends of HPC with another nonionic polymer such as HEC yield water solutions having viscosities in agreement with the calculated value. Blends of HPC and anionic CMC, however, produce solution viscosities greater than calculated. This synergistic effect may be reduced in the presence of dissolved salts or if the pH is below 3 or above 10. 

Wellan gum is produced by aerobic fermentation. The backbone of wellan gum is identical to gellan gum, but it has a side chain consisting of L-mannose or L-rhamnose. It is used in fluid loss additives and is extremely compatible with calcium ions in alkaline solutions. 

Xanthan gum dissolves in acids and bases, and under certain conditions, the viscosity remains stable for several months. Xanthan gum has excellent stability and compatibility with high concentrations of many salts, eg, 15% solutions of sodium chloride and 25% solutions of calcium chloride (79). 

Solutions of rhamsan have high viscosity at low shear rates and low gum concentrations (90). The rheological properties and suspension capability combined with excellent salt compatibility, make it useful for several industrial applications including agricultural fertilizer suspensions, pigment suspensions, cleaners, and paints and coatings. 

Food-grade CMC is a cellulose carboxylic acid ether with an optimum DS = 0.4-0.7. The higher the DS within this range, the more hydrophilic is the polyanion. Uniformity of substitution makes CMC more compatible with dissolved salts and less inclined to thixotropy than uneven distribution (Feddersen and Thorp, 1993). This gum does not precipitate from a 50% ethanol solution. Below approximately pH 4 in water, the polyanions revert to the un-ionized, water-insoluble acid. CMC viscosity-hysteresis has already been described (Fig. 2 in Chapter 3). CMC dispersions and films have the extra advantage of transparency relative to many other polysaccharide dispersions. The films are resistant to oils, grease, and organic solvents (Hercules, Inc., 1980). 

The most widely used synthetic and natural enhanced oil recovery polymers, such as partially hydrolyzed polyacrylamide, carboxymethyl(ethyl) cellulose, polysaccharides, or xanthan gums, are not suitable for high-temperature reservoirs (> 90 °C) with high-density brine fluid due to excessive hydrolysis and precipitation [277]. The main advantages of polymeric betaines over the mentioned standard polymers are (1) thermostability (up to 120 °C) (2) brine compatibility and (3) viscosification in brine solution [278]. Carbobetaines grafted onto hydroxyethyl cellulose were tested as a drilling-mud additive for clay hydration inhibition and mud rheological control [279]. An increase in the content of carbobetaine moieties resulted in an enhanced inhibitive abiUty, especially for sahne mud. 

Xanthan gum is an anionic material and is not usually compatible with cationic surfactants, polymers, or preservatives as precipitation occurs. Anionic and amphoteric surfactants at concentrations above 15% w/v cause precipitation of xanthan gum from a solution. 

Properties Soluble in water and many organic solvents. Compatible with a wide range of gums, resins, and plasticizers and with most metallic salts. Stable in acid and alkaline solutions. Available in a range of molecular weights. 

HPC is compatible with most water-soluble gums and resins, and yields homogeneous solutions with MC, hydroxyethyl cellulose (HEC), carboxymelhyl cellulose (CMC), guar, alginate, and locust bean gum, gelatin, sodium caseinate, poly(ethylene oxide), carbowax, etc. (Figure 26.2)... 

Gum Arabic acts as protective colloid and excellent emulsifier and the molecular aggregation can cause both shear thinning and time-dependent thickening behavior at low shear" Gum Arabic has the ability to create a strong protective film around oil droplets" and is compatible with the most other plant hydrocolloids, proteins, carbohydrates, and modified starches. The viscosity of a solution of a mixture of gum arabic and gum tragacanth tends to be lower than that of either constituent solution. 

CMC solutions offer good tolerance of water miscible solvents, good viscosity stabihty over the pH range of 4-10, compatibility with most water-soluble non-ionic gums, and synergism with hydroxyethyl cellulose (HEC) and hydroxypropyl cellulose (HPC)... 

Preventative measures Three biocides are being evaluated to ameliorate microbial effects without degrading the polymer solution itself. The three biocides are acrolein, formaldehyde, and Visco 3991 (2,2-dibromo-3-nitrilopropionamide). The biocides are evaluated in terms of compatibility with the xanthan gum polymer and ability to restrain bacterial growth. 

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