Viscosity losses

Aqueous solutions can be stabilized against viscosity loss by addition of 5—10 wt % anhydrous isopropyl alcohol, ethanol, ethylene glycol, or propylene glycol. The manganous ion (Mn " ) also is an effective stabilizer at concentrations of 10 -10 wt% of the solution. 

Metal- Working and Hydraulic Fluids. In the preparation of fluids for metal-working and hydrauflcs, the trend has been to replace organic-based materials with aqueous-based materials. Neodecanoic acid has found apphcation in these newer fluids as a corrosion inhibitor and a viscosity improver. For example, neodecanoic acid is used in an aqueous hydrauflc fluid concentrate for corrosion inhibition and improved antiwear properties (101), in the preparation of a thickened aqueous hydrauflc fluid to reduce viscosity loss (102), and in a water-soluble metal working oil to reduce corrosion (103). In a similar vein, neodecanoic acid has been used in antifreeze concentrates for corrosion inhibition (104). 

The immobilised Pectolyase Y-23 was used to perform consecutive depectinisations of a cloudy apple juice in batch reactions. After five reaction cycles, the percentage reduction of viscosity was greater than 90%. The viscosity of the apple juice feed through a bed of inactive y-alumina spheres remains unchanged thus confirming that the viscosity loss attributable to pectin adsorption on the carrier is negligible. The alcohol tests, performed on the juices previously treated with the... 

The effects of microbial infection are viscosity loss, pH change, gassing, malodour and visible surface growth. In addition, discoloration and alteration in the rheology of the formulation can result in the product being unacceptable to the customer. 

Viscosity loss (Figure 8) is brought about by enzymes, mainly cellulases, produced as organisms break down components such as cellulose ether thickeners. 

Hydrolysis rate measurements. Hydrolysis rates were examined by mixing polymer solutions with hydrochloric acid, in apparatus previously described (5). Solutions of polymer and acid are mixed rapidly, and the torque on a rotating PTFE coated fork, attached to a Brookfield LVTD viscometer, recorded as a function of time. Decreases in viscosity were approximated to first-order, and half-lives for viscosity loss calculated. 

Under many conditions, the viscosity of HEC solutions falls about 100 times faster than that of xanthan solutions. The rate of viscosity loss of Shellflo-S solutions, on the other hand is comparable with that of xanthan solutions at temperatures below the transition temperature, and comparable with that of HEC solutions above. 

Transition temperature and stability are, therefore, closely linked. The rate of viscosity loss of both xanthan and succinoglycan solutions increases about 100 fold as the molecules become disordered above T. This may be a problem, as some users of xanthan in heavy brines have discovered, but it can be used to advantage. 

Viscosity Loss Vith Tine. Poly(l-amidoethylene) solutions lose viscosity with time(5l). Several authors have attributed this viscosity loss to oxygen or radical degradation of the polymer(5l), but Francois(52) has shown that changes in viscosity only occur in solutions made from broad-molecular-weight-distribution poly( 1-amidoethylene). Since very... 

ISO 585 1990 Plastics - Unplasticized cellulose acetate - Determination of moisture content ISO 1061 1990 Plastics - Unplasticized cellulose acetate - Determination of free acidity ISO 1598 1990 Plastics - Cellulose acetate - Determination of insoluble particles ISO 1599 1990 Plastics - Cellulose acetate - Determination of viscosity loss on moulding ISO 1600 1990 Plastics - Cellulose acetate - Determination of light absorption on moulded specimens produced using different periods of heating ISO 1875 1982 Plastics - Plasticized cellulose acetate - Determination of matter extractable by diethyl ether... 

Table 2 contains the characteristics of the amic ester-aryl ether copolymers including coblock type, composition, and intrinsic viscosity. Three series of copolymers were prepared in which the aryl ether phenylquinoxaline [44], aryl ether benzoxazole [47], or aryl ether ether ketone oligomers [57-59] were co-re-acted with various compositions of ODA and PMDA diethyl ester diacyl chloride samples (2a-k). The aryl ether compositions varied from approximately 20 to 50 wt% (denoted 2a-d) so as to vary the structure of the microphase-separated morphology of the copolymer. The composition of aryl ether coblock in the copolymers, as determined by NMR, was similar to that calculated from the charge of the aryl ether coblock (Table 2). The viscosity measurements, also shown in Table 2, were high and comparable to that of a high molecular weight poly(amic ethyl ester) homopolymer. In some cases, a chloroform solvent rinse was required to remove aryl ether homopolymer contamination. It should also be pointed out that both the powder and solution forms of the poly(amic ethyl ester) copolymers are stable and do not undergo transamidization reactions or viscosity loss with time, unlike their poly(amic acid) analogs.

In many cases simple and only relatively accurate procedures are adequate for winery control purposes. Recently a number of 5-minute methods were developed in Europe (23a, 24, 25), and Schmitt (26) notes that in these semimicro procedures (1 ml) care must be used to avoid loss of volatile material, such as alcohol, and to make accurate volumetric measurements with wines of varying viscosity. Losses during distillation must also be minimized. 

Moreover, we found that the viscosity loss was equally great (Table IV) when methanol, acetone, or water were used in place of dimethoxypro-pane, or even when dioxane and HC1 were used alone. (Despite large decrease in viscosity, the loss in weight of the cellulose was always only about 1-2%). If the extraction of lignin by dioxane depended only upon the breakdown of the carbohydrate, we might have expected that equal degrees of degradation would have produced more nearly equal rates of extraction, but they did not. 

Inhibition Studies. A number of compounds were employed to study the amino acid residue(s) that are important for cellulase activity. Samples of enzyme (0.1 mL, 500 units) were pre-incubated with 0.1 mL of inhibitor in semimicroviscometers for 8 min at 35°C. CM-cellulose solution (0.8%, w/v), which had been separately equilibrated at 35°C for 20 min was added to the viscometers and initial viscosity losses were measured after 15 min. Inhibitors were replaced by buffer in control experiments. Compounds that are insoluble in buffer, e.g., N-ethylmalei-mide, diisopropyl fluorophosphate, and succinic anhydride, were dissolved in a small volume of 95% ethanol before assay. p-Chloromercuribenzoate (p-CMB) was first dissolved in 0.2M NaOH and the pH adjusted to eight prior to pre-incubation with cellulases. 

We are ignoring radiation losses, viscosity losses, and any possible turbulence. For most flames these are quite fair approximations. 

Fig. 12. Depemlence of viscosity, loss angle tangent and optical density on time of curing of a melamine-formaldehyde resin in solution and in bulk [81]. T = 80°. Concentration of fte solution 40% (1) 50% (2) 57% (3)...

Effects of Ironic Ions Fignre 5.22 shows the ferric ion (Fe ) effect on an HPAM viscosity at room temperatnre. The initial viscosity was 72.9 mPa s. We can see that when the Fe concentration was low, the viscosity loss was not... 

Figure 5.23 shows the 1000 mg/L HPAM viscosity in a closed system without oxygen at 30°C and 3 hours after adding Fe ". When Fe " concentration was lower than 10 mg/L, the viscosity loss was less than 10% owing to the salinity effect. However, when the HPAM solution was put in an open system, the viscosity was significantly lost, as shown in Figure 5.23. In the open system, Fe was oxidized to Fe. For comparison, the viscosity loss 6 hours after...

Biological degradation refers to the microbial breakdown of macromolecules of polymers by bacteria during storage or in the reservoir. Although the problem is more prevalent for biopolymers, biological attack may also occur for synthetic polymers. It has been found that HPAM can provide nutrition to sulfate-reducing bacteria (SRB). As the number of SRB increases, HPAM viscosity decreases. For example, when the number of SRB reaches 36000/mL, the viscosity loss of HPAM of 1000 mg/L is 19.6% (Luo et al., 2006). 

There are four bacteria in reservoirs, and their concentrations are in the order of TGB-0 > TGB-A > HOB > SRB. Their effect on polymer viscosity loss is shown in Fignre 5.34. Their concentrations were 2% with 10 bacteria in 1 mL liquid (these concentrations are much higher than typical values in reservoirs, though). The polymer concentration was 1000 mg/L. 

The viscosity loss from the static mixer to the injection wellhead was mainly caused by chemical degradation due to It was found that concentrations at the static mixer, injection well, and in the solution returned from the injection well were 0.3, 0.6, and 10 mg/L. Experimental data showed that the viscosity loss reached 77% when the solution had 2 mg/L Fe. If 100,400, or 800 mg/L formaldehyde was added, the viscosity loss was 67%, 56%, or 36%, respectively (Pang et al., 1998a). 

When the injection volume was up to 0.1 PV, the water-cut reduction and oil rate increase slowed down, and polymer stopped breaking through high-permeability channels (Xie et al., 2001). The weak gel was made of 400 mg/L HPAM and 60 mg/L Cr. Its viscosity was 130 mPa-s after aging 180 days at 50°C. Compared with 1000 mg/L polymer solution that was used before gel injection, the weak gel cost was reduced by 21% (Fan et al., 2004). Produced water was used to make the polymer solution. It was observed that if the produced water from producers was used inunediately, polymer solution viscosity loss was up to 60%. However, if the produced water was used some time after it was produced, the viscosity loss was significantly reduced (Xie et al., 2001). 

One ton of polymer injected increased 241 tons of oil recovered for PO and 209 tons for PT. The polymer solution viscosity loss was 12% at injection pump, 30% at injection wellhead, 57% 30 m away from the injector, and 70% cumulatively 106 m away from the injector (Yang et al., 1996). These data show that the viscosity loss occurred mainly from the injection pump to the reservoir near the injection well. The viscosity loss in the reservoir was also caused by higher salinity. Therefore, we can see that the viscosity shear loss in the reservoir was less significant. 

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